Topiramate

Antiepileptic with multiple mechanisms

ATC code: N03AX11

Brand names: Topamax, Topamac, Trokendi XR, Qsymia

Updated 17 Jul 2026 · Methodology

Indications

Migraine prophylaxis

First line

First-line in migraine prophylaxis per /AHS 2012 and EFNS 2009 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.

Sources

Cochrane Database Syst Rev: Topiramate for the prophylaxis of episodic migraine in adults. (2013)
AEMPS: Ficha técnica de Topiramato (2024)
AAN: Evidence-based guideline update: pharmacologic treatment for episodic migraine prevention in adults: report of the Quality Standards Subcommittee of the American Academy of Neurology and the American Headache Society. (2012)
Eur J Neurol: EFNS guideline on the drug treatment of migraine--revised report of an EFNS task force. (2009)

ICD-10: G43.9 · ICD-11: 8A80.Z

Focal epilepsy

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 levetiracetam – more cognitive side effects (mental fogginess, word-finding problems).

Sources

ICD-10: G40.2 · ICD-11: 8A60

Marketing claims without evidence base

The drug is promoted for these uses outside international guidelines. Each entry below is analyzed against AEMPS, FDA, EMA, Cochrane and major RCTs.

Weight loss

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.

Sources

How to read tiers A–F

AStrong evidence – first or second line in international guidelines
BRecommended in selected cases
CStudy data contradict each other
DBenefit not proven, no documented harm
FDocumented harm, or risk without benefit

Mechanism of action

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.

Safety

Contraindications

Topiramate hypersensitivity
Metabolic acidosis
Pregnancy (for migraine prophylaxis and obesity)
Angle-closure glaucoma
Age under 2

Serious adverse effects

Acute angle-closure glaucoma (rare, early in therapy)
Metabolic acidosis
Kidney stones (2–4× risk)
Oligohidrosis and hyperthermia in children
Depression and suicidal ideation
Teratogenicity (cleft lip/palate, hypospadias)

Common adverse effects

Paraesthesia (tingling fingers)
Cognitive impairment, mental fogginess
Weight loss
Fatigue
Drowsiness
Reduced appetite
Taste alteration (metallic)

Pregnancy: can you take Topiramate?

AEMPS summary of product characteristics (section 4.6): topiramate is teratogenic in mice, rats and rabbits, and in humans it crosses the placenta, with similar concentrations in umbilical cord and maternal blood. Pregnancy registry data show that first-trimester exposure to topiramate monotherapy increases the risk of congenital malformations, particularly cleft lip and palate and hypospadias (major malformations in 4.3% versus 1.4% without antiepileptic drugs in the North American registry, and up to 9.5% versus 3.0% in a Nordic study), with a dose-dependent risk; low birth weight (under 2,500 g) and small for gestational age (18% versus 5%) are also more common. Two Nordic registry studies (almost 300 children) suggest a 2–3-fold higher prevalence of autism spectrum disorders, intellectual disability or ADHD compared with children of mothers with epilepsy not exposed to antiepileptic drugs, while a US cohort (about 1,000 children) did not suggest an increase up to 8 years of age. Topiramate is contraindicated in pregnancy for migraine prophylaxis and, in epilepsy, unless there is no suitable alternative treatment; if it is used during pregnancy, the patient is referred to a specialist and careful prenatal monitoring is done. In women of childbearing potential, topiramate is contraindicated without highly effective contraception: a pregnancy test is done before starting, and at least one highly effective method (such as an intrauterine device) or two complementary methods including a barrier method are used during treatment and for at least 4 weeks after stopping.

Breastfeeding: can you take Topiramate?

High milk concentrations. Infant diarrhea and drowsiness are possible – monitor activity and weight gain.

Peak milk concentration: 2.3 mg/L

Calculate RID Full profile on NIH LactMed ↗

Reference information, not a clinical decision. Discuss feeding pauses or changes with your physician or an IBCLC.

Practical notes

Timing and administration

Take twice daily, with or without food, preferably at the same time. Adequate hydration is important to prevent kidney stones (1.5–2 L water daily) – carbonic anhydrase inhibition raises calcium stone risk. With eGFR under 70, halve the dose. Do not combine with other carbonic anhydrase inhibitors (acetazolamide) – additive effects on electrolytes.

Label mentions56 mentions

Verbatim lines from the interaction sections, in the language of the label

From this drug’s label

MajorCarbamazepine
«Fenitoína y carbamazepina disminuyen las concentraciones plasmáticas de topiramato. La adición o retirada de fenitoína o carbamazepina al tratamiento con topiramato puede provocar la necesidad de un…»
AEMPS, section 4.5 · Open on CIMA
MajorPhenytoin
«Fenitoína y carbamazepina disminuyen las concentraciones plasmáticas de topiramato. La adición o retirada de fenitoína o carbamazepina al tratamiento con topiramato puede provocar la necesidad de un…»
AEMPS, section 4.5 · Open on CIMA
ModerateCarbamazepine
«Antiepileptic Drugs: Concomitant administration of phenytoin or carbamazepine with topiramate resulted in a clinically significant decrease in plasma concentrations of topiramate when compared to…»
FDA, section 7 · Open on DailyMed
ModerateCNS depressantsclass named in the label
«CNS Depressants: Concomitant administration of topiramate and alcohol or other CNS depressant drugs has not been evaluated in clinical studies. Because of the potential of topiramate to cause CNS…»
FDA, section 7 · Open on DailyMed
ModerateDigoxin
«Digoxina: En un estudio de dosis única, el área bajo la curva de digoxina en plasma (AUC) disminuyó un 12% debido a la administración concomitante de topiramato. No se ha establecido la importancia…»
AEMPS, section 4.5 · Open on CIMA
ModerateHydrochlorothiazide
«Hidroclorotiazida (HCTZ): En un estudio sobre interacciones farmacológicas realizado en voluntarios sanos se evaluaron las farmacocinéticas en estado estacionario de HCTZ (25 mg cada 24 horas) y…»
AEMPS, section 4.5 · Open on CIMA
ModerateLithium
«DRUG INTERACTIONS: Monitor lithium levels if lithium is used with high-dose topiramate ( 7.7 )»
FDA, section 7 · Open on DailyMed
ModerateMetformin
«Metformina: Se recomienda una vigilancia estrecha del control de la diabetes cuando se introduzca o suspenda un tratamiento con topiramato en pacientes tratados con metformina.»
AEMPS, section 4.5 · Open on CIMA
ModeratePhenytoin
«Antiepileptic Drugs: Concomitant administration of phenytoin or carbamazepine with topiramate resulted in a clinically significant decrease in plasma concentrations of topiramate when compared to…»
FDA, section 7 · Open on DailyMed
ModeratePioglitazone
«Pioglitazona: En un estudio sobre interacciones farmacológicas realizado en voluntarios sanos se evaluaron las farmacocinéticas en estado estacionario de topiramato y pioglitazona administrados solos…»
AEMPS, section 4.5 · Open on CIMA
ModeratePioglitazone
«Pioglitazone: A decrease in the exposure of pioglitazone and its active metabolites were noted with the concurrent use of pioglitazone and topiramate in a clinical trial. The clinical relevance of…»
FDA, section 7 · Open on DailyMed
ModerateWarfarin
«Warfarina: Se ha notificado una disminución del tiempo de protrombina/índice internacional normalizado (TP/INR) en pacientes tratados con topiramato en combinación con warfarina. Por tanto, se debe…»
AEMPS, section 4.5 · Open on CIMA
ModerateZonisamide
«Other Carbonic Anhydrase Inhibitors: Concomitant use of topiramate, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g., zonisamide or acetazolamide) may increase the…»
FDA, section 7 · Open on DailyMed
Amitriptyline
«Concentración de Topiramato a: Amitriptilina»
AEMPS, section 4.5 · Open on CIMA
Amitriptyline
«Amitriptyline: Some patients may experience a large increase in amitriptyline concentration in the presence of topiramate and any adjustments in amitriptyline dose should be made according to the…»
FDA, section 7 · Open on DailyMed
depresores del SNCclass named in the label
«Depresores del Sistema Nervioso Central: No ha sido evaluada en ensayos clínicos la administración concomitante de topiramato con alcohol y otros depresores del Sistema Nervioso Central (SNC). Se…»
AEMPS, section 4.5 · Open on CIMA
Diazepam
«Topiramato inhibe la enzima CYP2C19 y puede interferir con otros fármacos metabolizados a través de esta enzima (p. ej. diazepam, imipramina, moclobemida, proguanilo, omeprazol).»
AEMPS, section 4.5 · Open on CIMA
Dihydroergotamine
«Concentración de Topiramato a: Dihidroergotamina (oral y subcutánea)»
AEMPS, section 4.5 · Open on CIMA
Diltiazem
«Concentración de Topiramato a: Diltiazem»
AEMPS, section 4.5 · Open on CIMA
Flunarizine
«Concentración de Topiramato a: Flunarizina»
AEMPS, section 4.5 · Open on CIMA
Glibenclamide
«Glibenclamida: En un estudio de interacción fármaco-fármaco realizado en pacientes con diabetes tipo 2 se evaluó la farmacocinética en estado estacionario de glibenclamida (5 mg/día) sola y…»
AEMPS, section 4.5 · Open on CIMA
Haloperidol
«Concentración de Topiramato a: Haloperidol»
AEMPS, section 4.5 · Open on CIMA
hormonal contraceptivesclass named in the label
«DRUG INTERACTIONS: Contraceptives: decreased contraceptive efficacy and increased breakthrough bleeding, especially at doses greater than 200 mg/day ( 7.4 )»
FDA, section 7 · Open on DailyMed
Hydrochlorothiazide
«Hydrochlorothiazide (HCTZ): Topiramate C max and AUC increased when HCTZ was added to topiramate. The clinical significance of this change is unknown. The addition of HCTZ to topiramate may require a…»
FDA, section 7 · Open on DailyMed
Lamotrigine
«Los resultados de un estudio sobre interacciones farmacocinéticas en pacientes con epilepsia indicaron que la adición de topiramato a lamotrigina no tuvo efecto sobre la concentración plasmática en…»
AEMPS, section 4.5 · Open on CIMA
Lithium
«Litio: En voluntarios sanos, se observó una reducción (18% de la AUC) en los valores sistémicos del litio durante la administración concomitante de 200 mg/día de topiramato. En pacientes con…»
AEMPS, section 4.5 · Open on CIMA

From other drugs’ labels

MajorDesogestrel
«Tratamiento de larga duración: Sustancias que aumentan el aclaramiento de las hormonas anticonceptivas (disminución de la eficacia anticonceptiva por inducción enzimática), por ejemplo: Barbitúricos…»
AEMPS, section 4.5 · Open on CIMA
MajorEthinylestradiol
«Tratamiento de larga duración: Barbitúricos, bosentán, carbamazepina, fenitoína, primidona, rifampicina y los medicamentos para el VIH ritonavir, nevirapina y efavirenz y, también posiblemente…»
AEMPS, section 4.5 · Open on CIMA
MajorZonisamide
«Inhibidores de la anhidrasa carbónica: Zonisamida no se debe utilizar concomitantemente con otros inhibidores de la anhidrasa carbónica tales como topiramato y acetazolamida en pacientes pediátricos…»
AEMPS, section 4.5 · Open on CIMA
ModeratePioglitazone
«Topiramate: A decrease in the exposure of pioglitazone and its active metabolites were noted with concomitant administration of pioglitazone and topiramate [see ] . The clinical relevance of this…»
FDA, section 7 · Open on DailyMed
ModerateValproic acid
«La administración concomitante de valproato y topiramato o acetazolamida se ha asociado con encefalopatía y/o hiperamonemia. En pacientes tratados con estos dos fármacos, deben monitorizarse…»
AEMPS, section 4.5 · Open on CIMA
ModerateZonisamide
«Drug Interactions: Other Carbonic Anhydrase Inhibitors: Concomitant use of zonisamide, a carbonic anhydrase inhibitor, with any other carbonic anhydrase inhibitor (e.g., topiramate, acetazolamide or…»
FDA, section 7 · Open on DailyMed
MinorEslicarbazepine acetate
«Topiramato: En un estudio en sujetos sanos, la administración concomitante de 1.200 mg de acetato de eslicarbazepina una vez al día y topiramato no mostró ningún cambio significativo en la exposición…»
AEMPS, section 4.5 · Open on CIMA
Amitriptyline
«Drug Interactions: Topiramate»
FDA, section 7 · Open on DailyMed
Carbamazepine
«Fármacos que pueden disminuir los niveles plasmáticos de carbamazepina: Antiepilépticos: clobazam, lamotrigina, eslicarbazepina, tiagabina, topiramato, clonazepam, etosuximida, primidona, ácido…»
AEMPS, section 4.5 · Open on CIMA
Estradiol
«El metabolismo de los estrógenos y progestágenos puede estar aumentado con el uso concomitante de sustancias que se sabe que inducen los enzimas metabolizadores de fármacos, específicamente los…»
AEMPS, section 4.5 · Open on CIMA
Estradiol valerate + Dienogest
«Effects of Other Drugs on Combined Oral Contraceptives: Drugs or herbal products that induce certain enzymes, including CYP3A4, may decrease the effectiveness of COCs or increase breakthrough…»
FDA, section 7 · Open on DailyMed
Flunarizine
«La farmacocinética de flunarizina no se vio afectada por la administración de topiramato.»
AEMPS, section 4.5 · Open on CIMA
Lamotrigine
«Fármacos que tienen poco o ningún efecto en la concentración de lamotrigina: Topiramato»
AEMPS, section 4.5 · Open on CIMA
Metformin
«DRUG INTERACTIONS: Examples: Topiramate, zonisamide, acetazolamide or dichlorphenamide.»
FDA, section 7 · Open on DailyMed

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Frequently asked

What is Topiramate used for?

Topiramate is evaluated for the following indications with varying evidence strength: Migraine prophylaxis (evidence tier A), Focal epilepsy (evidence tier B), Weight loss (evidence tier F). See the full indication matrix with dosing and citations above on this page.

What are the side effects of Topiramate?

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.

Is Topiramate safe during pregnancy?

Is Topiramate compatible with breastfeeding?

High milk concentrations. Infant diarrhea and drowsiness are possible – monitor activity and weight gain.

Who should not take Topiramate?

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.

Official sources

Direct links to regulator labels. Open in a new tab.

AEMPS / CIMALabel dated 06/17/2024
FDA / DailyMedLabel dated 09/01/2026

Other drugs in this group

Valproic acid, Zonisamide, Carbamazepine, Eslicarbazepine acetate, Lamotrigine, Phenobarbital, Gabapentin, Lacosamide