Mood Stabiliser (Sodium Channel Blocker) — Bipolar Disorder Pregnancy: SPC §4.6: carbamazepine crosses the placenta; first-trimester exposure is associated with an increased risk of major congenital malformations — meta-analysis found 4.93% (95% CI 3.84–6.16) with monotherapy versus a background rate of about 2–3%. Reported malformations include neural tube defects (spina bifida), craniofacial defects such as cleft lip/palate, cardiovascular malformations, hypospadias and other genitourinary defects, skeletal malformations, hypoplasia of the fingers and microcephaly; specialised antenatal surveillance is recommended. Increased risk of infants born small for gestational age. Neurodevelopmental disorders have been reported and a risk cannot be excluded. Specialist advice should be given to women of childbearing potential; monotherapy is preferred and sudden discontinuation of antiepileptic therapy should be avoided. (SPC text truncated at the fetch limit mid-sentence — 'Carbamazepine should not be used…' — so the final pregnancy recommendation and the lactation section were not retrieved and must be checked.)

Carbamazepine (Psychiatric Use)

Brand names: Tegretol, Tegretol Retard (modified-release)

Carbamazepine is used in psychiatry as a mood stabiliser, principally for the prophylaxis of bipolar affective disorder in patients unresponsive to lithium, and in acute mania.

Adult dose

Dose: Prophylaxis of manic depressive psychosis in patients unresponsive to lithium: initial 400 mg daily in divided doses, increased gradually until symptoms are controlled; usual dosage range 400–600 mg daily in divided doses

Route: Oral (source product: carbamazepine 100 mg/5 ml oral suspension; shake before use, may be taken during, after or between meals)

Frequency: In divided doses (carbamazepine oral suspension is usually given in two or three divided doses)

Max: Increase gradually to a maximum of 1200 mg daily in divided doses for this indication

SPC §4.2: 'For the prophylaxis of manic depressive psychosis in patients unresponsive to lithium therapy: Initial starting dose of 400 mg daily, in divided doses, increasing gradually until symptoms are controlled or a total of 1200 mg given in divided doses is reached. The usual dosage range is 400-600 mg daily, given in divided doses.' Adult patients who require doses exceeding 1200 mg up to 1600 mg/day of carbamazepine oral suspension should be switched to alternative oral formulations of carbamazepine, such as immediate-release and prolonged-release tablets. FORMULATION NOTE: a given dose of oral suspension produces higher peak levels than the same dose in tablet form — start with low doses of the liquid and increase slowly to avoid CNS effects such as dizziness and lethargy; when switching from tablets to liquid, the same overall daily dose may be used but in smaller, more frequent doses. Elderly (≥65 years): select the dose with caution because of the potential for drug interactions. PRE-TREATMENT GENETIC SCREENING: before starting, patients of Han Chinese and Thai origin should whenever possible be screened for HLA-B*1502, which strongly predicts the risk of severe carbamazepine-associated Stevens–Johnson syndrome. Plasma-level monitoring: in epilepsy the SPC quotes total plasma carbamazepine of about 4–12 micrograms/ml (17–50 micromoles/litre); no target range is stated for the psychiatric indication. PAEDIATRIC: the SPC gives no paediatric dose for this psychiatric indication — the per-kg figures in §4.2 (usual 10–20 mg/kg bodyweight daily in divided doses; maximum 35 mg/kg/day from ≥4 weeks to 6 years, 1000 mg/day for 6–15 years, 1200 mg/day for >15 years) belong to the EPILEPSY indication and must not be applied to psychiatric use. The oral suspension is contraindicated in children under 4 weeks of age (propylene glycol excipient). For any under-18 use, verify against a children's formulary.

Dose adjustments

Renal

SPC §4.2 special populations: 'No data are available on the pharmacokinetics of carbamazepine in patients with impaired hepatic or renal function.'

Dose independently re-sourced from UK Summary of Product Characteristics (SPC) via the eMC; US FDA prescribing information (openFDA / DailyMed) — cross-check; US labelling may differ from UK — clinician-reviewed. Always confirm against the product SmPC and your local formulary before prescribing.

Contraindications

Known hypersensitivity to carbamazepine or structurally related drugs (e.g. tricyclic antidepressants) or any other component of the formulation
Atrioventricular block
History of bone marrow depression
History of hepatic porphyrias (e.g. acute intermittent porphyria, variegate porphyria, porphyria cutanea tarda)
Combination with monoamine oxidase inhibitors (MAOIs)
Oral suspension: children less than 4 weeks of age (propylene glycol excipient)

Side effects

Very common/common at the start of treatment or if the initial dose is too high: dizziness, headache, ataxia, drowsiness, fatigue, diplopia; nausea and vomiting; allergic skin reactions
Very common: leucopenia. Common: thrombocytopenia, eosinophilia
Common: oedema, fluid retention, weight increase, hyponatraemia and decreased blood osmolarity due to an ADH-like effect (rarely water intoxication with lethargy, vomiting, headache, confusion)
Rare: delayed multi-organ hypersensitivity disorder (fever, rash, vasculitis, lymphadenopathy, pseudolymphoma, arthralgia, leucopenia, eosinophilia, hepatosplenomegaly, abnormal liver function tests, vanishing bile duct syndrome); folate deficiency, decreased appetite
Very rare/not known: agranulocytosis, aplastic anaemia, pancytopenia, bone marrow depression; anaphylactic reaction, angioedema; DRESS; Stevens–Johnson syndrome and toxic epidermal necrolysis (see §4.4); galactorrhoea, gynaecomastia

Interactions

Monoamine oxidase inhibitors (MAOIs) — contraindicated; the US label advises discontinuing an MAOI for a minimum of 14 days before carbamazepine
Nefazodone — coadministration contraindicated (US label): carbamazepine lowers nefazodone and active-metabolite concentrations below therapeutic levels
CYP3A4 inhibitors increase plasma carbamazepine levels — e.g. aprepitant, cimetidine, ciprofloxacin, danazol, diltiazem, macrolides (erythromycin, clarithromycin), fluoxetine (US label list, truncated at fetch limit); monitor levels and adjust dose
Carbamazepine is an enzyme inducer and is itself named in other SPCs as an inducer of glucuronidation/CYP3A4 (e.g. it lowers lamotrigine levels and is contraindicated with lurasidone) — check co-prescribed psychotropics
Other antiepileptics — when carbamazepine is added to existing antiepileptic therapy this should be done gradually, maintaining or adapting the dose of the other antiepileptic(s)
Liquid formulation: carbamazepine oral suspension must not be given at the same time as other liquid medicines or diluents — precipitate formation has been reported with liquid chlorpromazine and thioridazine

Clinical monograph

How it works

It stabilises hyperexcitable neuronal membranes mainly by blocking voltage-gated sodium channels, reducing repetitive neuronal firing and pathological neurotransmission.

Prescribing in practice

It is a potent inducer of hepatic enzymes and therefore reduces the effectiveness of many co-prescribed drugs, including hormonal contraceptives, so interaction checks are essential.
Warn patients about signs of blood, liver and skin disorders (including potentially life-threatening rashes such as Stevens-Johnson syndrome) and the increased serious-cutaneous-reaction risk associated with the HLA-B*1502 allele in relevant ancestries.
It is teratogenic and should be avoided in pregnancy and in women of childbearing potential not using effective contraception unless there is no safer alternative.

Monitoring

Monitor full blood count, liver function and, where indicated, plasma carbamazepine concentration, alongside review of mood and emergent rashes.

Counselling the patient

Seek urgent medical advice if you develop a fever, mouth ulcers, bruising, a rash or yellowing of the skin.
This drug can stop hormonal contraception working, so discuss reliable contraception.
Do not stop suddenly without medical advice.

Evidence & guidelines

Carbamazepine is recognised in NICE guidance as a mood-stabilising option in bipolar disorder; MHRA advice highlights teratogenicity and serious cutaneous reactions.

Reference: NICE CG185 (Bipolar Disorder); MHRA HLA-B*1502 Safety Update; Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. The structured dose values shown have been reviewed by a clinician. Monograph status: clinician-reviewed (2026-07-04).

Curated clinical cross-links plus same-class fallbacks.

Calculators

Pathways