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Pharmacology · Mood stabilizers

Lithium carbonate !

The classic mood stabilizer for bipolar disorder. Its safe range is narrow, so blood levels are checked and toxicity signs watched.

Updated 2026-11-01

  • Class: Mood stabilizers
  • Enzyme: Inositol monophosphatase and GSK-3 (proposed)
  • ATC code: N05AN01
  • WHO Model List of Essential Medicines

Mechanism of action

Lithium is a simple ion. Its mood-stabilising mechanism is not fully known; the leading ideas are that it inhibits inositol monophosphatase, dampening phosphatidylinositol signalling, and that it inhibits GSK-3. The kidney handles it like sodium, which explains why low sodium, dehydration and some drugs raise its levels.

  1. Lithium inhibits inositol monophosphatase and GSK-3
  2. Phosphatidylinositol signalling in neurons is dampened
  3. Fewer manic and depressive relapses over time
  4. The kidney treats it like sodium: low sodium raises lithium

Pharmacokinetics

Absorption
Taken by mouth (immediate- and extended-release forms, solution)
Metabolism
Not metabolised
Elimination
By the kidney, in proportion to its blood level; reduced kidney function raises toxicity risk

Indications

  • Acute manic and mixed episodes of bipolar I disorder
  • Maintenance treatment of bipolar I disorder

Adverse effects

Common

  • Fine hand tremor
  • Polyuria and thirst
  • Nausea, diarrhoea and abdominal discomfort early on
  • Weight gain
  • Acne and rash

Contraindications

  • Severe kidney impairment (avoided)
  • Brugada syndrome or suspected Brugada syndrome (avoided)
  • Marked dehydration or sodium depletion
  • Hypersensitivity to lithium

Key interactions

Thiazide and other diuretics
Higher lithium levels and toxicity
NSAIDs
Higher lithium levels
ACE inhibitors and ARBs
Higher lithium levels
Antipsychotics (haloperidol and others)
Rare encephalopathic syndrome; also additive neurotoxicity
SSRIs and other serotonergic drugs
Serotonin syndrome

What is monitored

  • Serum lithium level, drawn just before the next dose, regularly and after any change in dose, other drugs or health
  • Kidney function and electrolytes (sodium)
  • Thyroid function
  • Calcium
  • ECG when there are cardiac risk factors
  • Pregnancy status in women who could become pregnant

Administration and safety

  • Immediate- and extended-release forms are different products and are not substituted for each other unnoticed
  • Blood for levels is drawn at trough, just before the next dose
  • Kidney function, electrolytes, thyroid function and pregnancy status are checked before starting

Nursing care

  • Watches for early toxicity (diarrhoea, vomiting, coarse tremor, unsteadiness, drowsiness) and holds the next dose pending review if they appear
  • Teaches the patient to keep a steady salt and fluid intake and to avoid dehydration in heat, exercise, fever or diarrhoea
  • Teaches to avoid over-the-counter NSAIDs and to report any new prescription (diuretics, ACE inhibitors)
  • Checks that levels and kidney and thyroid tests are up to date

Pregnancy and breastfeeding

First-trimester use has been linked to Ebstein's anomaly and other heart defects, with a smaller risk than once thought; newborns can show lithium toxicity. Use weighs relapse risk against fetal risk.

Test yourself

Think of the answer, then tap the question to see it.

Why are lithium levels measured regularly?

Its therapeutic range is narrow: toxicity can occur at levels close to the effective ones.

A patient on lithium starts hydrochlorothiazide and an NSAID and develops coarse tremor and confusion. What happened?

Lithium toxicity: both drugs reduce renal lithium excretion and raise its level.

What is the treatment of choice for severe lithium toxicity?

Haemodialysis, which removes lithium quickly.

Which drug may be used for lithium-induced nephrogenic diabetes insipidus?

Amiloride.

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Educational content on how drugs work; not a prescribing guide and no substitute for a health professional's advice. No doses are given.

Sources: DailyMed - LITHIUM CARBONATE tablet (DailyMed (U.S. National Library of Medicine), 2026); Lithium: MedlinePlus Drug Information (MedlinePlus (U.S. National Library of Medicine), 2026); Goodman & Gilman's The Pharmacological Basis of Therapeutics, 14th ed., ch. 19 (McGraw Hill, 2023).

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