Section 01 · Monograph

Carbamazepine

Reviewed Nov 2026FDA label

TegretolNa+ channel blocker

Black Box Warning

Serious and sometimes fatal dermatologic reactions, including toxic epidermal necrolysis (TEN) and Stevens-Johnson syndrome (SJS), have been reported — risk is estimated at roughly 1–6 per 10,000 new users in populations of mostly European ancestry, but is about 10 times higher in some Asian countries
Strongly associated with the HLA-B*1502 allele — patients with ancestry in genetically at-risk populations (e.g., Han Chinese, other Asian ancestries) should be screened for HLA-B*1502 before initiating treatment; avoid use in patients testing positive unless benefit clearly outweighs risk
Aplastic anemia and agranulocytosis have been reported in association with carbamazepine, at a rate estimated to be several times greater than the general population background risk

Partial seizures with complex symptomatology (psychomotor, temporal lobe)FDA-labeled
Generalized tonic-clonic seizuresFDA-labeled
Mixed seizure patternsFDA-labeled
Trigeminal neuralgia painFDA-labeled
Acute manic and mixed episodes associated with bipolar I disorder (extended-release formulation)FDA-labeled

Blocks voltage-gated Na+ channels, stabilizing hyperexcited neuronal membranes and inhibiting repetitive neuronal firing
Reduces synaptic transmission of excitatory signals

Initiate 200mg twice daily (immediate-release), titrate by increments up to 200mg/day at weekly intervals divided BID–QID to effective dose
Usual maintenance range approximately 800–1200mg/day, divided according to formulation
Extended-release formulations dosed twice daily
Because of autoinduction of its own metabolism, dose requirements often need to be increased during the first several weeks of therapy

Known hypersensitivity to carbamazepine or structurally related tricyclic compounds
Concomitant use of MAO inhibitors or use within 14 days of MAOI discontinuation
Concomitant use with nefazodone
History of previous bone marrow suppression
Known HLA-B*1502 allele, unless the benefit clearly outweighs the risk

Strong CYP3A4 inducer; induces its own metabolism (autoinduction) — half-life decreases from roughly 25–65 hours after a single dose to 12–17 hours with repeated dosing, typically completing over 3–5 weeks
Reduces efficacy of hormonal contraceptives via induction of hormone metabolism — breakthrough bleeding and unintended pregnancies have been reported; alternative or additional contraception recommended
Reduces plasma concentrations of warfarin and many other CYP3A4/CYP2C substrates
Concomitant use with MAOIs is contraindicated
CYP3A4 inhibitors (e.g., erythromycin, certain azoles) can raise carbamazepine levels and precipitate toxicity
Complex bidirectional interaction with valproate affecting levels of both drugs

Common: dizziness, drowsiness, ataxia, nausea, vomiting, blurred vision
Hyponatremia/SIADH
Blood dyscrasias, including aplastic anemia, agranulocytosis, and thrombocytopenia — see boxed warning
Serious dermatologic reactions including SJS/TEN — see boxed warning
DRESS syndrome and other multiorgan hypersensitivity reactions
Hepatotoxicity

CBC with differential and platelet count at baseline and periodically
Liver function tests
Serum sodium
HLA-B*1502 testing in genetically at-risk populations before initiating treatment
Carbamazepine serum drug levels, particularly during dose titration (autoinduction)
Skin — instruct patients to report rash immediately

Associated with increased risk of congenital malformations, including neural tube defects, with in-utero exposure
Consider enrollment in the North American Antiepileptic Drug (NAAED) Pregnancy Registry
Present in breast milk; weigh benefits of breastfeeding against potential infant exposure