Antiepileptic with multiple mechanisms
ATC code: N03AX11 (Topiramate)
Brand names
Topamax, Topamac, Trokendi XR, Qsymia
Blocks voltage-gated sodium channels, enhances GABA action at GABA-A receptors, inhibits AMPA/kainate glutamate receptors, and inhibits carbonic anhydrase. The multimechanism action underlies efficacy in epilepsy and migraine prophylaxis. Reduces appetite and weight – used off-label in obesity (in the US, approved combined with phentermine). Minimally metabolized; mostly renally excreted.
Second line
Second-line for focal and generalized epilepsy in adults and children over 2 per ILAE 2017. Starting dose 25 mg at bedtime with slow titration to 200–400 mg daily over 5–6 weeks. Less tolerable than lamotrigine and – more cognitive side effects (mental fogginess, word-finding problems).
First line
First-line in migraine prophylaxis per /AHS 2024 and EFNS 2022 alongside β-blockers (propranolol, metoprolol). Reduces attack frequency by 50% in 35–50% of patients. Dose 50–100 mg daily in 2 doses. In obese patients, an added benefit – weight loss of 3–5 kg.
The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.
Not recommended
Topiramate is an antiepileptic drug. It is prescribed for epilepsy and migraine prophylaxis ( 2018, NG150). Topiramate is actively used off-label for weight loss and as part of the phentermine/topiramate combination (Qsymia, -approved for BMI ≥ 30 or ≥ 27 with comorbidities). In people with normal weight, topiramate is not justified for weight loss. The drug has serious risks: cognitive disturbances (word-finding difficulty, memory impairment), paresthesias, weight loss with muscle atrophy risk, nephrolithiasis, metabolic acidosis, teratogenicity (FDA category D – risk of cleft palate and other fetal defects), and angle-closure glaucoma. If topiramate was prescribed for weight loss to a woman of reproductive age or to a person with normal weight, consider seeking a second opinion.
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FDA category D. T1 use raises cleft lip/palate risk 2–3 fold and hypospadias and low birthweight. Contraindicated for migraine prophylaxis and obesity in pregnancy; in epilepsy, decisions are made with an epileptologist, switching to lamotrigine or levetiracetam where possible.
High milk concentrations. Infant diarrhea and drowsiness are possible – monitor activity and weight gain.
Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.
Topiramate is evaluated for the following indications with varying evidence strength: Focal epilepsy (evidence tier A), Migraine prophylaxis (evidence tier A), Weight loss (evidence tier F). See the full indication matrix with dosing and citations above on this page.
Common side effects of Topiramate (≥ 1 in 100): Paraesthesia (tingling fingers), Cognitive impairment, mental fogginess, Weight loss, Fatigue, Drowsiness, Reduced appetite. See the Safety section for uncommon and serious reactions.
FDA category D. FDA category D. T1 use raises cleft lip/palate risk 2–3 fold and hypospadias and low birthweight. Contraindicated for migraine prophylaxis and obesity in pregnancy; in epilepsy, decisions are made with an epileptologist, switching to lamotrigine or levetiracetam where possible.
High milk concentrations. Infant diarrhea and drowsiness are possible – monitor activity and weight gain.
Topiramate is contraindicated in: Topiramate hypersensitivity; Metabolic acidosis; Pregnancy (for migraine prophylaxis and obesity); Angle-closure glaucoma; Age under 2. Full list in the Safety section.