Information last reviewed: May 2026 — for educational purposes only.
What Is Tegretol (Carbamazepine)?
Carbamazepine, branded as Tegretol, is a first-generation iminostilbene antiepileptic. It blocks voltage-gated sodium channels in their activated state, reducing repetitive firing of epileptic neurons. Carbamazepine is also a potent CYP3A4 inducer — it induces its own metabolism (autoinduction) and accelerates the metabolism of many co-administered drugs. Drug interaction monitoring is critical, particularly with oral contraceptives, warfarin, other AEDs, and immunosuppressants. Extended-release formulations (Tegretol XR, Carbatrol) provide more stable plasma levels with fewer side effects. Therapeutic level monitoring is routine.
Prescription (Rx) Status
Carbamazepine is prescription-only. Black-box warnings include aplastic anaemia, agranulocytosis, and SJS/TEN (especially in patients of Han Chinese, Thai, and other East/Southeast Asian ancestry who may carry HLA-B*1502 — genetic testing recommended before starting). Hyponatraemia (low sodium) is a notable side effect. Monthly CBC initially, then periodic monitoring.
Uses of Carbamazepine
FDA-approved: complex partial seizures, generalised tonic-clonic seizures, mixed seizure patterns, and trigeminal neuralgia (drug of choice). Off-label: bipolar I disorder (acute mania), postherpetic neuralgia, and restless legs syndrome.
Tablet Strengths
Immediate-release tablets: 100 mg and 200 mg. Chewable tablets: 100 mg. XR tablets (Tegretol XR): 100 mg, 200 mg, 400 mg. Suspension: 100 mg/5 mL. For trigeminal neuralgia: starting 100 mg twice daily; titrate to 400–800 mg/day. For epilepsy: 400–1200 mg/day in divided doses. Target serum levels: 4–12 mcg/mL.
Price
Generic carbamazepine is inexpensive (~$15–$35/month). XR generics also available and affordable.
Frequently Asked Questions
Q: Should patients of Asian ancestry have genetic testing before starting carbamazepine?
A: Yes — the FDA recommends HLA-B*1502 testing in patients of Han Chinese, Thai, Filipino, Malaysian, and some South Asian ancestry before initiating carbamazepine, due to significantly elevated risk of SJS/TEN in HLA-B*1502 carriers.
Q: What drugs does carbamazepine interact with?
A: Carbamazepine induces CYP3A4 and reduces levels of oral contraceptives, warfarin, many AEDs (lamotrigine, valproate), antidepressants, antipsychotics, and immunosuppressants. A complete drug interaction review is essential before starting or stopping.
Q: What are early signs of toxicity?
A: Diplopia (double vision), nystagmus, dizziness, and ataxia. These may signal supratherapeutic levels. Serum level and clinical assessment guide dose adjustment.
Disclaimer: This page is for informational purposes only and does not constitute medical advice. Carbamazepine requires a valid prescription. Always consult a qualified healthcare professional. See our full disclaimer.