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Antiepileptic / Trigeminal neuralgia

Carbamazepine

Brand names: Tegretol, Carbagen

Used in: Seizures & Epilepsy

Carbamazepine is an antiepileptic used for focal seizures, for trigeminal neuralgia, and as a mood stabiliser.

Dosing — being independently re-sourced

ClinCalc Pro is rebuilding its dose data from primary open sources — the manufacturer SmPC (eMC), the WHO Model Formulary and other official references — under clinician review. This drug's structured dose is not yet published here. Confirm all doses against the product SmPC and your local formulary before prescribing.

US labelling (FDA)

Reference — US labelling, may differ from UK

DOSAGE AND ADMINISTRATION (SEE TABLE BELOW) Carbamazepine suspension in combination with liquid chlorpromazine or thioridazine results in precipitate formation, and, in the case of chlorpromazine, there has been a report of patient passing an orange rubbery precipitate in the stool following coadministration of the two drugs (see PRECAUTIONS, Drug Interactions). Because the extent to which this occurs with other liquid medications is not known, Carbamazepine suspension should not be administered simultaneously with other liquid medications or diluents. Monitoring of blood levels has increased the efficacy and safety of anticonvulsants (see PRECAUTIONS, Laboratory Tests). Dosage should be …

Source: US FDA prescribing information (openFDA / DailyMed), label dated 2025-02-18. Accessed 2026-06-12. US dosing and indications can differ from UK practice — use UK sources for prescribing decisions.

Clinical monograph

How it works

It stabilises neuronal membranes by blocking voltage-gated sodium channels.

Prescribing in practice

  • It is a strong enzyme inducer with many interactions, and it lowers the effectiveness of numerous drugs including hormonal contraceptives.
  • Serious rashes (Stevens-Johnson syndrome) occur, with higher risk in people carrying HLA-B*1502 (test in relevant ancestries); hyponatraemia and blood dyscrasias also occur.
  • It is teratogenic — specialist advice is needed around pregnancy; titrate slowly and avoid abrupt withdrawal.

Monitoring

Monitor for rash and check FBC, sodium and liver function; carbamazepine levels can guide dosing; review interacting drugs.

Counselling the patient

  • Report any rash, sore throat, fever, bruising or yellowing of the skin/eyes.
  • It can make other medicines (including the contraceptive pill) less effective — get advice.
  • Do not stop it suddenly.

Evidence & guidelines

An option for focal epilepsy and first-line for trigeminal neuralgia (NICE CG137/CG173), with important interaction, rash and pregnancy cautions.

Reference: NICE CG137; MHRA Drug Safety Update (HLA-B*1502); Drug verified in RxNorm (NLM); confirm dosing against the manufacturer SPC (eMC). Verify against your local formulary and current prescribing references before prescribing. Monograph status: clinician-reviewed (2026-07-04).

Related

Curated clinical cross-links plus same-class fallbacks.

Pathways