Mood Stabilizer Adverse Events · Section 1 · Chapter 1 · Lithium: Acute Toxicity & Level Problems
Lithium Toxicity: Recognition, Severity and When to Send to the ED
Acute, acute-on-chronic and chronic toxicity behave differently, and the serum level alone will mislead you in at least one of them. This chapter is about deciding, in the next hour, whether your patient needs an emergency department.
The 30-second version
- Three presentations, three risk profiles. Decide first whether this is acute, acute-on-chronic or chronic toxicity. The same level means something different in each, and chronic toxicity is the one where the number understates the danger.
- Recognition: what toxicity looks like. Listen for a change in the tremor, unsteadiness, slurred speech or muddled thinking, and for diarrhoea. The patient's usual fine tremor is not the sign; a change in it is.
- Reading the level without being fooled by it. A level without the time of the last dose and the time of the draw is half a result, and in suspected toxicity one level is never enough. The trend answers the question.
- Grading severity at the bedside. Grade severity on the neurological examination. The classic grading contains no lithium concentration at all.
- What else it could be. Hold lithium and assess in person whatever the alternative. The differential decides what else the emergency department needs to hear from you.
- Who gets toxic, and why now. Almost always, something lowered renal lithium clearance: fluid loss, a drug that makes the kidney hold sodium or filter less, or falling kidney function. Find it, because it is still acting.
- When to send to the ED. Any new neurological sign, any intentional or sustained-release ingestion, fluids not staying down, kidney injury, a cardiac symptom, or features of NMS or serotonin toxicity: emergency department now, whatever the level.
- What the ED will do, and what you should ask for. Stop lithium, restore volume and sodium, limit further absorption, and remove lithium directly when the patient or the kidney needs it. Your referral should carry what the team needs to decide on the last step.
- After the episode: restart or not. Make the restart decision explicitly. "Lithium held" in a discharge summary is not a plan.
At the bedside · Suspected lithium toxicity: the next ten minutes
About 2 min to read · the detailed chapter follows below
Do now
- Hold the next lithium dose. Do not wait to see the patient first.
- Ask the five questions below.
- Triage red, amber or green on the patient, whatever the level says.
- If red: call the emergency department and send the handover list.
- After recovery, make the restart decision explicitly. "Lithium held" is not a plan.
Do not
- Advise drinking large volumes of water to "flush out" lithium. Free water does not correct sodium depletion and can worsen hyponatraemia.
- Add or increase a diuretic.
- Wait for a clinic appointment in two days if any neurological sign is new.
- Restart at the previous dose after a missed day or two without a repeat level.
- Act on a single level without the time of the last dose and the time of the draw.
Five questions on the phone
- Is the tremor different from usual? Bigger movements, worse when reaching, spilling drinks, now in the legs or jaw.
- Unsteady, slurred or confused? Any of these is a new neurological sign, whatever the level.
- Vomiting or diarrhoea, and can they keep fluids down? Fluid loss drives accumulation, and it keeps acting while you wait.
- Any new medicine, or fever? Name them: blood pressure tablets, water tablets, anti-inflammatories bought over the counter.
- Could they have taken extra, and which tablets? Any intentional or sustained-release ingestion goes to the emergency department.
Emergency department now if any of
- New neurological sign beyond the usual fine tremor
- Intentional ingestion, or any sustained-release overdose
- Cannot keep fluids down, or ongoing diarrhoea
- Known or suspected kidney injury
- Syncope, palpitations or a slow pulse
- Rigidity with fever, or clonus with agitation, in a patient on an antipsychotic or serotonergic drug
Same-day in-person assessment if any of
- Level above target with gastrointestinal symptoms only
- Fever or infection with reduced, but maintained, fluid intake
- Recent interacting drug start plus any illness
- You cannot examine the patient or trust the history
- Older patient who lives alone, with no one to observe
Outpatient, with a safety net
Well patient, level mildly above target, cause identified: hold lithium, stop the precipitant, repeat trough level and creatinine promptly, give clear return advice.
Prescriber-side triage for suspected lithium toxicity. Our synthesis of label warnings and toxicology reviews, not a validated instrument [1][3][6]. The top box is deliberately inclusive: over-referral costs an emergency visit, under-referral can cost permanent neurological injury.
Why one level misleads
- Acute ingestion: the first level can understate the peak, especially with sustained-release tablets. Trend it.
- Acute-on-chronic: a high level on top of an already-loaded brain.
- Chronic: the brain has caught up, so neurotoxicity can sit alongside a modestly raised level. This carries the highest neurotoxicity risk.
Send the emergency department
- Formulation and dose
- Time of the last dose and of the level draw
- Any intentional or sustained-release ingestion
- Baseline creatinine and any history of polyuria
- Interacting drugs started, and any antipsychotic or serotonergic drug
Look up a presentation
Tap the presentation for who it is, what the level tells you and the main trap. The same level means something different in each.
Highest neurotoxicity risk
Intermediate
Lowest neurotoxicity risk
Chronic toxicity
Highest neurotoxicity riskAct on the neurological examination, not on the number.
Who and what you see
- Patient on a stable dose whose lithium elimination has fallen
- No overdose has occurred
- Dehydration, an intercurrent illness, a new drug that reduces renal lithium clearance, declining kidney function, or a dose increase
- Coarse tremor, unsteadiness, slurred speech, confusion, often with poor intake or diarrhoea
The level and the trap
- Understates severity; neurotoxicity can be marked at a modestly raised level
- Neurological toxicity can be established at serum levels that do not look alarming [3][1]
- Adjusting the dose by phone because "the level is only a bit high"
- Any new neurological sign sends the patient to the emergency department, whatever the level
Acute-on-chronic toxicity
IntermediateA high level on top of an already-loaded brain.
Who and what you see
- Patient on maintenance lithium who takes an extra large amount
- Gastrointestinal and neurological signs together
- Their risk of neurotoxicity sits between the other two [3]
The level and the trap
- Treating it like an acute ingestion and expecting the neurological picture to lag
- Every intentional or sustained-release ingestion goes, however well the patient looks
Acute toxicity
Lowest neurotoxicity riskDo not accept a single early level after a sustained-release ingestion; the emergency department should trend it.
Who and what you see
- Lithium-naive patient, single large ingestion
- Gastrointestinal symptoms first; neurological signs may be delayed
- A patient who looks well with a high level is not reassuring [3]
The level and the trap
- High early level may overstate current brain exposure but can understate the eventual peak with sustained-release tablets
- Discharging a patient who "looks fine" before the level has been trended
- Every intentional or sustained-release ingestion still goes to the emergency department
Serum and brain lithium over time (figure)
Figure 1. Conceptual only, not drawn to scale and not derived from measured data. In acute ingestion, serum lithium rises before brain lithium; in chronic accumulation the two have equilibrated, so neurotoxicity can sit alongside a serum level that looks only modestly raised. Explanation adapted in our own words from toxicology reviews [3].
Three presentations, three risk profiles
Decide first whether this is acute, acute-on-chronic or chronic toxicity. The same level means something different in each, and chronic toxicity is the one where the number understates the danger.
| Presentation | Who | What the level tells you | Early picture | Main trap |
|---|---|---|---|---|
| Acute | Lithium-naive patient, single large ingestion | High early level may overstate current brain exposure but can understate the eventual peak with sustained-release tablets | Gastrointestinal symptoms first; neurological signs may be delayed | Discharging a patient who "looks fine" before the level has been trended |
| Acute-on-chronic | Patient on maintenance lithium who takes an extra large amount | High level on top of an already-loaded brain | Gastrointestinal and neurological signs together | Treating it like an acute ingestion and expecting the neurological picture to lag |
| Chronic | Patient on a stable dose whose lithium elimination has fallen | Understates severity; neurotoxicity can be marked at a modestly raised level | Coarse tremor, unsteadiness, slurred speech, confusion, often with poor intake or diarrhoea | Adjusting the dose by phone because "the level is only a bit high" |
Each row of that table should be read on its own. The tint follows the ranking of neurotoxicity risk in the toxicology review: lowest after an acute ingestion, intermediate in acute-on-chronic poisoning, highest in chronic toxicity [3]. A low tint on the acute row does not make an acute ingestion safe to manage by phone. Every intentional or sustained-release ingestion still goes to the emergency department, for the reasons given in the triage section below. Chronic toxicity carries the highest tint, and it is also the presentation in which the number most often misleads prescribers into treating it as an outpatient dose problem. The neurological cost of that error can be permanent [5].
Our case
Eleven years of maintenance therapy, no overdose, a new drug that reduces lithium clearance, a second new drug that does the same, and several days of fluid loss. This is chronic toxicity until proven otherwise. The 1.9 mEq/L may well understate what is happening in her brain, and it was drawn at an unknown time after the last dose.
The detail: why the three presentations differ
The single most useful thing you can do in the first minute is decide which of three presentations you are looking at. Toxicology reviews consistently separate lithium poisoning into acute, acute-on-chronic and chronic forms, because the three differ in where the lithium is when you draw the level [3]. The distinction is not academic. It determines how much weight the number can bear.
Lithium is a small ion that is not bound to protein, distributes first through extracellular fluid and only then, slowly, into cells, including neurons. The brain concentration lags the serum concentration on the way up and lags it again on the way down [3]. That lag is the whole story of why the three presentations look different.
Acute toxicity is a single large ingestion in someone who was not taking lithium. The serum level can be very high early, while the brain has not yet caught up. The first hours are often dominated by gastrointestinal symptoms: nausea, vomiting, diarrhoea. Neurological signs may be mild at first and then appear or worsen as lithium moves into tissue, which is why a patient who looks well with a high level is not reassuring [3].
Acute-on-chronic toxicity is a large ingestion in someone already on maintenance lithium. The tissues are already loaded, so the new lithium arrives on top of an established body burden. These patients combine the high serum levels of acute ingestion with the tissue saturation of chronic therapy. Their risk of neurotoxicity sits between the other two: higher than after an acute ingestion, lower than in chronic toxicity [3].
Chronic toxicity is the one psychiatric prescribers meet most often, and the one with the highest risk of neurotoxicity [3]. No overdose has occurred. The patient has taken the same dose, but elimination has fallen: dehydration, an intercurrent illness, a new drug that reduces renal lithium clearance, declining kidney function, or a dose increase. Lithium accumulates slowly, the brain equilibrates with it, and neurological toxicity can be established at serum levels that do not look alarming [3][1].
Recognition: what toxicity looks like
Listen for a change in the tremor, unsteadiness, slurred speech or muddled thinking, and for diarrhoea. The patient's usual fine tremor is not the sign; a change in it is.
| System | Earlier or milder | Later or severe | What it changes |
|---|---|---|---|
| Neurological | Coarse tremor, unsteady gait, slurred speech, drowsiness, poor concentration, muscle twitching | Confusion, agitation, myoclonus, hyperreflexia, clonus, seizures, reduced consciousness, coma | Any sign beyond the patient's usual fine tremor moves the decision toward the emergency department |
| Gastrointestinal | Nausea, vomiting, diarrhoea | Persistent vomiting or diarrhoea with dehydration | Fluid loss reduces lithium clearance, so gastrointestinal toxicity can drive further accumulation |
| Renal | Polyuria and thirst, often pre-existing | Acute kidney injury; high sodium when a concentrating defect meets poor intake | A fall in kidney function removes the main exit route; it is both cause and consequence |
| Cardiac | Bradycardia, T-wave flattening or inversion | Sinus node dysfunction, conduction block, arrhythmia | Needs an ECG in the emergency department; conduction effects are covered in Chapter 19 (releasing soon) |
Do not let the usual tremor reassure you
"She always shakes a bit" is the most dangerous sentence in a lithium phone call. Ask specifically whether the tremor has changed: bigger movements, worse when reaching, spilling drinks, now in the legs or jaw. A change in the character of the tremor, with unsteadiness or muddled thinking, is toxicity until shown otherwise.
Two findings deserve emphasis because they are easy to miss on the phone. The first is new or worsening diarrhoea. It is both an early symptom of toxicity and a cause of worse toxicity, because volume loss makes the kidney hold on to sodium and, with it, lithium. The second is new polyuria with poor intake in an older patient. A lithium-related urinary concentrating defect means she keeps losing water even as she drinks less, and the resulting dehydration further reduces lithium clearance [1][3].
The detail: the systems involved, and how families describe it
Lithium toxicity announces itself mainly through the nervous system and the gut, with the kidney and the heart as the organs that most often change management. The US label lists the clinical picture of toxicity across these systems in its warnings on lithium toxicity [1].
The problem at the point of care is that the early neurological signs of toxicity overlap with side effects many patients have lived with for years. A fine tremor of the hands is common on therapeutic lithium. The change you are listening for is a shift in character: the tremor becomes coarse, the gait becomes unsteady, the speech becomes slurred, the patient becomes slowed or muddled. Families often notice these before clinicians, and they describe them in ordinary words: "wobbly," "drunk," "not herself," "can't hold a cup."
Reading the level without being fooled by it
A level without the time of the last dose and the time of the draw is half a result, and in suspected toxicity one level is never enough. The trend answers the question.
| Pitfall | What happens | What to do |
|---|---|---|
| Sustained-release overdose | Absorption continues for hours; an early level can sit well below the eventual peak | Do not accept a single early level after a sustained-release ingestion; the emergency department should trend it |
| Random timing in maintenance therapy | A level drawn soon after a dose reads higher than the trough | Record the time of the last dose and the draw on every result; compare like with like |
| Chronic toxicity with a modest level | Neurotoxicity established at a level that looks only a little high | Act on the neurological examination, not on the number |
| Falling level, persisting symptoms | Brain lithium leaves more slowly than serum lithium | Expect neurological recovery to lag the level; a normalising number does not end observation |
The detail: trough timing, the trend, and rebound
The serum lithium level is essential and frequently misread. Three questions decide whether a given number can be trusted: when was it drawn relative to the last dose, which formulation is the patient taking, and is it one value or a trend.
Maintenance monitoring is standardised on a trough level taken about twelve hours after the last dose. The US label specifies drawing the sample immediately before the next dose, about twelve hours after the previous one, once levels are stable [1]. A level drawn a few hours after a dose will read higher than the trough for the same patient on the same regimen. That matters in both directions: a post-dose level can look toxic in a patient who is not, and a random level in a toxic patient cannot be compared with her previous troughs.
In suspected toxicity the level still helps, but its role changes. You are no longer asking whether the dose is right. You are asking how much lithium is on board, whether it is still rising, and whether elimination is working. One level answers none of those questions well. Repeated levels, with the time of each draw and the time of the last dose recorded, answer all three [3].
The last row is worth dwelling on. After haemodialysis in particular, serum lithium can fall quickly and then rise again as lithium moves back out of cells, a rebound that the US label and toxicology reviews both anticipate by advising close monitoring of levels after treatment [1][3]. The same principle applies to the patient you manage without dialysis: the neurological picture can take days to clear, and occasionally it does not clear.
Grading severity at the bedside
Grade severity on the neurological examination. The classic grading contains no lithium concentration at all.
| Grade | Clinical picture (paraphrased) | Practical meaning for a prescriber |
|---|---|---|
| Mild | Nausea, vomiting, tremor, hyperreflexia, agitation, muscle weakness, ataxia | Already beyond an outpatient dose adjustment if new neurological signs are present; same-day assessment |
| Moderate | Stupor, rigidity, hypertonia, hypotension | Emergency department now |
| Severe | Coma, seizures, myoclonus, cardiovascular collapse | Emergency services; the emergency department should be discussing extracorporeal treatment |
Notice what the grading does not include: a lithium concentration. That omission is deliberate in the source and deliberate here. The level still matters for decisions about extracorporeal treatment, which is covered below, but it does not tell you how sick your patient is.
A contested point, named as contested
There is no single agreed severity score for lithium toxicity. Clinical grading, level thresholds and the extracorporeal-treatment criteria each capture part of the risk. We have not attempted to merge them into one scale, because doing so would claim a consensus that does not exist. Use the clinical grade to decide urgency and leave the treatment thresholds to the receiving team.
The detail: where the grading comes from, and its limits
Because the level misleads in chronic toxicity, severity is graded clinically. A widely cited clinical grading, from a 1978 case series and reproduced in a later toxicology review, divides lithium intoxication into three grades by neurological state rather than by concentration [4][3]. We use it here as a shared vocabulary for triage, not as a validated prognostic score. The review that reproduces it notes that the original series was drawn mostly from patients with chronic toxicity, which limits its use for relating levels to severity after an acute ingestion [3]. A poison-centre series went further and found the classification did not predict morbidity or mortality and did not correlate well with lithium levels [7]. That is one more reason to grade the patient rather than the number, and not to treat any grade as a prognosis.
What else it could be
Hold lithium and assess in person whatever the alternative. The differential decides what else the emergency department needs to hear from you.
A confused, tremulous patient on lithium has lithium toxicity until a level and an examination say otherwise, but anchoring on it causes its own harm. Several conditions look similar, and some occur because of the same drugs the patient takes alongside lithium. The fuller differential for neurological syndromes on lithium, including lithium combined with antipsychotics and serotonin toxicity, is the subject of Chapter 3. Here the aim is narrower: to know what must not be missed before the patient leaves your hands.
| Condition | What points toward it | Why it matters in a lithium patient |
|---|---|---|
| Neuroleptic malignant syndrome | Antipsychotic co-prescription, lead-pipe rigidity, fever, autonomic instability, raised creatine kinase | The US lithium label warns of an encephalopathic syndrome with lithium plus an antipsychotic, and its drug-interaction section describes neurotoxic reactions ranging from extrapyramidal symptoms to neuroleptic malignant syndrome; the pictures overlap [1] |
| Serotonin toxicity | Serotonergic co-prescription, clonus (especially inducible or ocular), hyperthermia, agitation, diarrhoea | The current label lists serotonin syndrome as a warning with serotonergic combinations [1] |
| Hyponatraemia or hypernatraemia | Diuretic use, vomiting, poor intake, polyuria | Sodium disturbance causes confusion on its own and changes lithium handling |
| Other intoxication or co-ingestion | Intentional overdose, access to other drugs, alcohol | An intentional lithium ingestion is often not the only one |
| Central nervous system infection or stroke | Fever, meningism, focal signs, sudden onset | Older patients on lithium get strokes and infections too |
| Wernicke encephalopathy | Poor nutrition, alcohol use, ophthalmoplegia with ataxia | Weeks of poor intake can produce it alongside lithium accumulation |
| Relapse of the mood disorder | Pressured speech, reduced sleep, affective change without ataxia or coarse tremor | Mania can look like agitation; ataxia and dysarthria point away from it |
None of these alternatives changes the first step. Lithium is held, a level and basic chemistry are obtained, and a patient with new neurological signs is assessed in person the same day. The differential decides what else the emergency department needs to hear from you, and that is part of a good handover.
Who gets toxic, and why now
Almost always, something lowered renal lithium clearance: fluid loss, a drug that makes the kidney hold sodium or filter less, or falling kidney function. Find it, because it is still acting.
Chronic toxicity almost always has a cause, and the cause is almost always a fall in renal lithium clearance. Lithium is filtered and then reabsorbed largely alongside sodium in the proximal tubule. Anything that makes the kidney conserve sodium, or that lowers glomerular filtration, raises lithium. That one principle explains most of the list [3].
Figure 2. Why lithium builds up. Conceptual summary in our own words of the precipitants the label and toxicology reviews describe; it is not a ranking of how often each occurs, and the mechanism differs by drug class, as the table below sets out [1][3].
The US label lists drug interactions that can raise serum lithium, and it identifies dehydration, sodium depletion and intercurrent illness as situations that increase the risk of toxicity [1]. The detailed management of each interaction, including drugs that lower lithium levels, belongs in Chapter 2. Here the question is only which risk factors should raise your urgency today.
| Risk factor | How it raises lithium | Triage weight |
|---|---|---|
| Vomiting, diarrhoea, fever, poor oral intake | Volume and sodium depletion increase proximal reabsorption | High: often the precipitant in chronic toxicity, and it continues while you wait. Fever during toxicity has also been linked with persisting neurological sequelae in a systematic review [6] |
| Acute kidney injury or falling estimated glomerular filtration | Removes the main route of elimination | High: toxicity will keep worsening until clearance recovers |
| Recent start of an ACE inhibitor | Compensatory proximal reabsorption of sodium and lithium, and reduced filtration | High, particularly in older patients and when combined with any illness or dehydration. The mechanism is well described; the admission data conflict (see the box below) |
| Recent start of an angiotensin receptor blocker | Assumed to act like an ACE inhibitor; the label groups them together | Treat like an ACE inhibitor in practice, but the direct evidence is weaker: case reports and extrapolation rather than controlled data [8][1] |
| Recent start of a thiazide diuretic | Compensatory proximal reabsorption of sodium and lithium | High: the most consistent effect on lithium clearance in controlled pharmacokinetic studies |
| Recent start of a loop diuretic | Mainly through volume and sodium depletion rather than a direct clearance effect | High in older or comorbid patients, where admissions for toxicity cluster; smaller effect in controlled studies of healthy volunteers |
| Regular NSAID use | Reduced renal prostaglandin-dependent clearance | High when combined with a RAAS drug or a diuretic |
| Older age | Lower baseline clearance, more co-prescribed drugs, less reserve | Moderate: lowers the threshold for in-person assessment |
| Recent dose increase or formulation change | More lithium in, or different absorption | Moderate: ask about it every time |
| Low-salt diet or new heavy sweating | Sodium depletion | Moderate: often missed because nobody asks |
| Pre-existing lithium-related polyuria | Water loss when intake falls | Contributory: turns a minor illness into dehydration quickly |
Our patient has three high-weight factors at once: a new ACE inhibitor, regular NSAID use and days of gastrointestinal fluid loss. Any one of them deserves attention. Together they make the phone assessment short.
The detail: contested evidence, named as contested
The interaction evidence points in more than one direction, because different kinds of study measure different things. Controlled pharmacokinetic studies find that thiazides reduce lithium clearance and loop diuretics have little effect under controlled conditions. A population-based study of older adults, as reported in a later review, found hospital admission for lithium toxicity associated with newly started loop diuretics and ACE inhibitors, while thiazides and NSAIDs did not reach statistical significance in that cohort [8]. A 2026 population-based cohort from Ontario, of lithium users aged 50 or older, found no significant difference in 90-day hospital admission for lithium toxicity after a new ACE inhibitor or ARB compared with a new beta-blocker, and a supplementary comparison against non-users was also not significant; the authors suggest the risk reported earlier may be overstated [9]. They are explicit that this is not evidence the combination is universally safe: the study counted only hospital admissions, not toxicity managed as an outpatient, residual confounding is possible, and ACE inhibitors and ARBs were analysed together. It also excluded patients who started the drug alongside a diuretic or an NSAID. That exclusion matters for this chapter, because an ACE inhibitor plus an NSAID, the combination in our case, is exactly what the study did not test. Controlled studies describe steady-state handling in healthy volunteers; the admission studies describe what happens to patients in practice, and they do not agree with each other. We have not tried to resolve them. The practical advice does not change: after any of these drugs is started, check the level rather than assume. A result that did not reach significance in one cohort is not evidence that thiazides or NSAIDs are safe with lithium, and the label lists all of these classes as interactions [1].
When to send to the ED
Any new neurological sign, any intentional or sustained-release ingestion, fluids not staying down, kidney injury, a cardiac symptom, or features of NMS or serotonin toxicity: emergency department now, whatever the level.
The triage itself is in the bedside panel at the top of this chapter. This section explains why each criterion is there, because experienced prescribers will push back on several of them. There is no guideline that gives a single outpatient cut-off, and we have not invented one: the framework is our synthesis of label warnings and toxicology reviews, not a validated instrument [1][3].
| Criterion | Why it is there |
|---|---|
| Any new neurological sign sends the patient to the emergency department, whatever the level | This is the rule chronic toxicity demands. Waiting for a level to "confirm" toxicity in an ataxic, dysarthric patient means waiting for a number that may never look frightening enough. |
| Every intentional or sustained-release ingestion goes, however well the patient looks | Absorption from sustained-release preparations can continue for many hours, and toxicology reviews describe delayed peaks [3]. A modest early level is not a safe discharge from your telephone. |
| Fluids not staying down, or ongoing diarrhoea | Fluid loss drives accumulation, and it keeps acting while you wait. |
| Known or suspected kidney injury | It removes the main route of elimination; toxicity keeps worsening until clearance recovers. |
| Syncope, palpitations or a slow pulse | Lithium affects cardiac conduction and the patient needs an ECG; conduction effects are covered in Chapter 19 (releasing soon). |
| Rigidity with fever, or clonus with agitation, on an antipsychotic or serotonergic drug | The label warns of an encephalopathic syndrome with antipsychotics and of serotonin syndrome [1]. See the differential in section 5. |
| Fever with maintained intake is amber, not red | A febrile patient who can still drink, with no new neurological sign, needs a level, creatinine and an examination today, not an emergency department by default. Fever has been linked with persisting neurological sequelae [6], so the moment fluids cannot be kept down or a neurological sign appears, red applies. If you cannot arrange same-day assessment, send the patient. |
| The outpatient box is narrow on purpose | It is for the well patient with no new neurological sign, a level only mildly above target, an identified and reversible cause, and someone who can watch them. We give no numerical ceiling for outpatient management because we could not locate one supported by two independent sources. |
What the ED will do, and what you should ask for
Stop lithium, restore volume and sodium, limit further absorption, and remove lithium directly when the patient or the kidney needs it. Your referral should carry what the team needs to decide on the last step.
| Element | What it involves | Point a prescriber should know |
|---|---|---|
| Stop lithium | No further doses; stop interacting drugs where safe | Includes the ACE inhibitor, NSAID or diuretic that precipitated it; say so in the referral |
| Restore volume and sodium | Intravenous isotonic fluid in the dehydrated patient, with close monitoring of sodium and urine output | The label advises monitoring for hypernatraemia during normal saline [1]. In our reading, a patient with a known lithium-related concentrating defect is the one most exposed to that risk, so the team needs any history of polyuria |
| Limit absorption | Whole-bowel irrigation may be considered after a large sustained-release ingestion | Activated charcoal does not bind lithium meaningfully; it is used only for co-ingestants [1][3] |
| Extracorporeal removal | Haemodialysis in selected patients, guided by published consensus recommendations | Criteria depend on kidney function, neurological state and level, not on level alone |
Each of these elements is supported in the toxicology reviews cited, but the specific regimens, fluid rates and irrigation protocols belong to the treating team and are not reproduced here [3].
Permanent injury is possible
A minority of patients are left with persistent neurological deficits after lithium toxicity, most often cerebellar: unsteadiness, tremor and dysarthria that do not resolve when the level falls. This has been described as the syndrome of irreversible lithium-effectuated neurotoxicity. It is the reason chronic toxicity with neurological signs is treated as an emergency rather than a dose problem [5][3].
The detail: the treatment logic, and the extracorporeal framework
You will not be running the resuscitation, but you will be writing the referral, and a good referral changes what happens in the first hour. It also helps to know the treatment logic, so that you can explain it to the family and recognise when something has been missed.
Management rests on four elements described in toxicology reviews: stop the lithium, restore circulating volume and sodium so the kidney can excrete lithium again, prevent further absorption where an ingestion is recent, and remove lithium directly with extracorporeal treatment when the patient is severely affected or the kidney cannot do the job [3].
The most widely used framework for deciding on extracorporeal treatment comes from the Extracorporeal Treatments in Poisoning workgroup, which published systematic-review-based recommendations for lithium poisoning [2]. Its logic is worth understanding even if you never order dialysis. The recommendations combine three kinds of information: kidney function, the patient's neurological and cardiac state, and the serum level, together with how long the level is expected to take to fall without treatment. Neurological deterioration, seizures or life-threatening arrhythmia support extracorporeal treatment regardless of the level; the level thresholds apply mainly when kidney function is impaired or elimination is expected to be slow.
Why we have not printed the dialysis thresholds
The extracorporeal-treatment criteria include specific lithium concentrations and a time-to-target estimate. They are the numbers most likely to be copied into a note, so they are the numbers that most need two independent readings of the primary text. Until that verification is complete, this chapter names the framework and its logic and leaves the thresholds to the source. The decision itself sits with the emergency and nephrology teams.
What you can usefully do is send the information those teams need to apply the criteria quickly. That is why the referral checklist in the action ladder below asks for the formulation, the time of the last dose, any sustained-release ingestion, the baseline kidney function, the history of polyuria and the list of interacting drugs.
After the episode: restart or not
Make the restart decision explicitly. "Lithium held" in a discharge summary is not a plan.
Once the patient has recovered, someone has to decide whether lithium continues. That decision is often made by default: the discharge summary says "lithium held," and the question drifts. Lithium is frequently the most effective long-term treatment the patient has had, and stopping it abruptly carries its own risk of early recurrence, discussed in Chapter 20 (releasing soon). Equally, a restart at the old dose, with the precipitants still in place, invites a second episode.
The restart decision rests on four questions:
- Was there a clear, reversible precipitant, and has it been removed? An NSAID can be stopped; a gastroenteritis resolves. Declining kidney function does not reverse, and that changes the calculation substantially; the kidney-specific decision is covered in Chapter 5 (releasing soon).
- Did the patient recover neurologically? Persistent deficits change the balance and warrant specialist review before any rechallenge.
- Is there an alternative that would protect this patient as well? That is a psychiatric judgement specific to the patient's illness history, not a toxicology one.
- Can the risk be managed? A lower target, a clear sick-day plan, removal of interacting drugs and closer early monitoring.
If lithium is restarted, it is restarted deliberately: a documented target range, a documented dose, a repeat trough level after the dose has had time to reach steady state, and a sick-day plan that the patient and family can repeat back to you. The sick-day plan itself, including which drugs to pause during vomiting or diarrhoea, is the core of Chapter 2.
Two cross-checks belong in every post-toxicity review. An ECG, because lithium affects cardiac conduction and a toxicity episode is a reasonable moment to establish a baseline; conduction effects are discussed in Chapter 19 (releasing soon), and generic QT management is in the Psychopharmacology with Cardiac Impairment course. And kidney function trended over time, not a single post-recovery value, because a toxicity episode is sometimes the first sign of a long-term decline.
Clinical pearls
- Classify first: acute, acute-on-chronic or chronic.The same number means different things in each.
- In chronic toxicity, the brain has caught up with the serum.Neurological signs at a modest level are the emergency, not the level.
- In acute ingestion, especially with sustained-release tablets, the first level is a starting point.The trend is the answer.
- Record the time of the last dose and the time of the draw on every lithium result you act on.A level without times is half a result.
- Diarrhoea is both a symptom and a cause of worse toxicity.Treat it as both.
- The precipitant is usually in the medication list or the recent illness history.Ask about blood pressure tablets, water tablets and anti-inflammatories by name; patients do not always count over-the-counter ibuprofen as a medicine.
- Neurological recovery lags the fall in the level, and occasionally does not complete.A normalising number does not end observation.
- After recovery, make the restart decision explicitly and write it down."Lithium held" is not a plan.
Family script & EMR note
Counselling script: to the patient or family, by phone
"Thank you for calling straight away. From what you're describing, I'm worried the lithium level has built up in her body. That can happen when someone has been unwell with vomiting or diarrhoea, or when a new medicine like a blood pressure tablet or an anti-inflammatory changes how the kidneys clear lithium.
Please don't give tonight's lithium dose. I'd like her to be seen in the emergency department today, not at the clinic on Thursday. The shakiness, the unsteadiness and the confusion are the reason: those are signs the lithium may be affecting her brain, and that needs checking and treating now rather than waiting.
Please take all her tablet bottles with you, including the new blood pressure tablet and anything she's bought over the counter, like ibuprofen. I'm going to call the emergency department and tell them she's coming and what I'm worried about.
Once she's recovered, we'll decide together whether lithium is still the right medicine and, if it is, how to make it safer, including what to do next time she's unwell. You haven't done anything wrong by calling. This is exactly the right time to."
EMR note: copy, paste and edit
LITHIUM TOXICITY – TELEPHONE / URGENT ASSESSMENT
Source of information: [patient / family member: relationship]
Lithium formulation and dose: [immediate / sustained-release], [dose, frequency]
Duration of lithium therapy: [ ]
Usual target range: [ ] mEq/L Most recent stable trough: [value, date]
Presentation type: [acute / acute-on-chronic / chronic accumulation]
Current level: [value] mEq/L Time drawn: [ ] Time of last dose: [ ]
(Level timing: [trough / random / unknown])
Symptoms:
Neurological: tremor change [Y/N], ataxia [Y/N], dysarthria [Y/N],
confusion [Y/N], myoclonus [Y/N], drowsiness [Y/N], seizure [Y/N]
Gastrointestinal: vomiting [Y/N], diarrhoea [Y/N],
able to keep fluids down [Y/N]
Fever / intercurrent infection [Y/N]
Rigidity with fever, or clonus with agitation [Y/N]
Renal: polyuria history [Y/N], known kidney impairment [Y/N]
Cardiac: syncope / palpitations / slow pulse [Y/N]
Precipitants identified:
[ ] ACE inhibitor / ARB [ ] thiazide / loop diuretic [ ] NSAID
[ ] recent dose change [ ] intercurrent illness / poor intake
[ ] intentional ingestion [ ] other: [ ]
Co-prescribed antipsychotic / serotonergic drugs: [ ]
Assessment: Suspected [chronic / acute / acute-on-chronic] lithium
toxicity, clinical severity [mild / moderate / severe] based on
neurological state; level interpreted in light of timing and
presentation type.
Plan:
[ ] Lithium held from 2026
[ ] Referred to emergency department [time]; handover given to
[name/role] including formulation, last dose time, SR ingestion,
baseline creatinine, polyuria history, interacting drugs
[ ] OR same-day in-person assessment arranged [time/place]
[ ] OR outpatient management: precipitant stopped [ ], repeat
trough level and creatinine 2026, return advice given
[ ] Restart decision to be made at review; not to restart by default
Return / emergency advice given to: [ ] Understood: [Y/N]
Clinician: [ ] Date/time: [ ]
Case: Tuesday, 4:40 pm
A 68-year-old woman with bipolar I disorder has taken lithium carbonate for eleven years. Her levels have sat comfortably in the lower half of her target range for the past three years, with a stable dose. Her daughter phones the clinic: for two days her mother has been "wobbly and not making sense," and this morning she dropped a cup because her hands were shaking.
Three weeks ago her primary care physician started lisinopril for blood pressure. Last week she began taking ibuprofen, several times a day, for a flare of knee pain. On Saturday she had vomiting and diarrhoea after a family meal; she has been eating and drinking very little since.
A lithium level was drawn at an urgent care centre at 11 am today. The daughter reads it to you over the phone: 1.9 mEq/L. Nobody recorded when the last dose was taken. The daughter asks whether her mother should just skip tonight's dose and come to clinic on Thursday.
By the end of this chapter you should be able to say what kind of toxicity this is, why the number is probably not the whole story, and exactly what to tell the daughter in the next five minutes.
Case resolution
The clinician asks the daughter three questions. Is the shaking different from usual? Yes: she spilled her tea and her hand "jumps" when she reaches. Is she unsteady or confused? Yes to both. Is she keeping fluids down? Barely.
The advice takes under two minutes. Do not give tonight's dose. Take her to the emergency department now, and bring every tablet bottle, including the new blood pressure tablet and the ibuprofen. The clinician calls the emergency department, gives a handover that names chronic toxicity, the ACE inhibitor, the NSAID, three days of fluid loss, a level of unknown timing and a long history of polyuria, and asks for an ECG and repeated levels.
In the department her creatinine has risen from her baseline and a repeat level remains raised. She is admitted, rehydrated with monitoring of her sodium, and the nephrology team is consulted about extracorporeal treatment given her neurological signs and reduced kidney function. Her confusion clears over several days; her gait takes longer.
At review, lisinopril is replaced with a blood pressure agent chosen with lithium interactions in mind, the ibuprofen is stopped with a documented alternative for her knee, and the psychiatrist and patient agree to restart lithium at a lower target with a written sick-day plan, an early repeat trough and a recorded ECG. The follow-up note records all of this as a decision, not a default.
Why you triage the patient, not the printout
A lithium level is a number drawn at one moment from blood. Lithium toxicity is what is happening in the brain, and the brain takes lithium up slowly and gives it back slowly. The patient with the frightening number may be walking and talking; the patient with the reassuring number may be the one who never fully recovers. You triage the patient, not the printout.
References (9)
- Lithium carbonate [US prescribing information]. Warnings and Precautions (lithium toxicity; renal effects; encephalopathic syndrome with antipsychotics; serotonin syndrome) and Drug Interactions. Hikma Pharmaceuticals USA Inc.; revised November 2022. DailyMed setid 7dc9c6d2-6d9a-49e4-a8ab-437b0ed5f84e. Source type: US structured product label.
- Decker BS, Goldfarb DS, Dargan PI, et al. Extracorporeal treatment for lithium poisoning: systematic review and recommendations from the EXTRIP Workgroup. Clin J Am Soc Nephrol. 2015;10(5):875–887. Source type: peer-reviewed systematic review with consensus recommendations.
- Baird-Gunning J, Lea-Henry T, Hoegberg LCG, Gosselin S, Roberts DM. Lithium poisoning. J Intensive Care Med. 2017;32(4):249–263. Source type: peer-reviewed narrative review.
- Hansen HE, Amdisen A. Lithium intoxication (report of 23 cases and review of 100 cases from the literature). Q J Med. 1978;47(186):123–144. Source type: peer-reviewed case series and literature review.
- Adityanjee, Munshi KR, Thampy A. The syndrome of irreversible lithium-effectuated neurotoxicity. Clin Neuropharmacol. 2005;28(1):38–49. Source type: peer-reviewed review.
- Verdoux H, Debruyne AL, Queuille E, de Leon J. A reappraisal of the role of fever in the occurrence of neurological sequelae following lithium intoxication: a systematic review. Expert Opin Drug Saf. 2021. Source type: peer-reviewed systematic review.
- Bailey B, McGuigan M. Lithium poisoning from a poison control center perspective. Ther Drug Monit. 2000. Source type: peer-reviewed retrospective case series.
- Finley PR. Drug interactions with lithium: an update. Clin Pharmacokinet. 2016. Source type: peer-reviewed narrative review; cited here for its report of the Juurlink 2004 population-based study and the controlled pharmacokinetic studies, neither of which was read directly.
- Ahmadi F, Muanda FT, McArthur E, Weir M, Garg AX. Lithium toxicity from angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker co-prescription: a population-based cohort study. J Psychopharmacol. 2026 (online ahead of print):1–11. doi:10.1177/02698811261473401. Source type: peer-reviewed population-based cohort study.
Last reviewed October 2026. Part of the Psychiatry Education Forum Academy, Managing Mood Stabilizer Adverse Events · Section 1 · Chapter 1.
Managing Mood Stabilizer Adverse Events
The rest of the course applies the same rapid-decision format to the serious adverse effects of lithium, valproate, lamotrigine, carbamazepine and oxcarbazepine: why a level moved, neurological syndromes that are not simple toxicity, kidney, thyroid and calcium effects, the rash that has to stop lamotrigine, and more.
This chapter is educational material for licensed prescribers and prescribers in training. It is not a substitute for clinical judgement, local protocols, poison centre advice or the current prescribing information. Lithium toxicity is a medical emergency; when in doubt, refer. Psychiatry Education Forum Academy is not a CME provider and this chapter does not carry CME credit.
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