Toxicity (coarse tremor, vomiting, diarrhoea, ataxia, slurred speech, confusion, seizures): stop lithium, check a level and U&E, rehydrate, and get urgent advice. Levels above 1.5 mmol/L, or symptoms at any level, are dangerous; above 2.0 may need haemodialysis.
Target levels
- 12 h post-dose serum level: usually 0.6 to 0.8 mmol/L (up to 1.0)
- Check weekly after starting or a dose change until stable, then every 3 months
- Narrow therapeutic range: small changes matter
Routine monitoring
- U&E and eGFR, and TFTs, every 6 months (more often if abnormal)
- Calcium (hyperparathyroidism), weight and BMI
- Ask about thirst and polyuria (nephrogenic diabetes insipidus)
Therapeutic (0.4 to 1.0)
- Level 12 h post-dose
- Check every 3 to 6 months
- Renal and thyroid every 6 months
Mild toxicity (1.5 to 2.0)
- Tremor, GI upset, drowsiness
- Withhold, check level and renal
- Rehydrate, find the trigger
Severe toxicity (over 2.0)
- Ataxia, seizures, arrhythmia
- IV fluids, consider haemodialysis
- Critical care
Counselling and safety
1
1. Consistency
Same brand and same time each day; do not double up missed doses.
Same brand and same time each day; do not double up missed doses.
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2. Interactions
NSAIDs, ACE inhibitors or ARBs, and thiazide diuretics raise lithium levels. Dehydration (vomiting, diarrhoea, hot weather) increases toxicity.
NSAIDs, ACE inhibitors or ARBs, and thiazide diuretics raise lithium levels. Dehydration (vomiting, diarrhoea, hot weather) increases toxicity.
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3. Sick-day and surgery
Maintain hydration, recheck the level if unwell or dehydrated, and review around surgery.
Maintain hydration, recheck the level if unwell or dehydrated, and review around surgery.
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4. Pregnancy and overdose
Teratogenic (Ebstein anomaly): pre-conception specialist plan. Check a level urgently after any overdose or new neurological symptoms.
Teratogenic (Ebstein anomaly): pre-conception specialist plan. Check a level urgently after any overdose or new neurological symptoms.
Give patients a record
- Lithium alert card and record book
- Symptoms of toxicity to watch for
- When and how to get a level checked
Pitfalls
- Adding an NSAID, ACE inhibitor or thiazide without rechecking
- Missing dehydration as a toxicity trigger
- Not monitoring renal, thyroid and calcium
- Abrupt discontinuation (relapse risk)
MedPrep - www.medprep.uk - Educational revision aid only. Not clinical guidance. Doses are adult examples; check the BNF, current guidelines and local policy, and seek senior advice. Nov 2026