Note: This document contains side effect information about topiramate. Some of the dosage forms listed on this page may not apply to the brand name Topamax.

Common side effects of Topamax include: anxiety, ataxia, confusion, diarrhea, diplopia, dizziness, drowsiness, dysphasia, fatigue, lack of concentration, memory impairment, nausea, nervousness, paresthesia, psychomotor disturbance, speech disturbance, depression, visual disturbance, weight loss, dysgeusia, mood changes, and anorexia. Other side effects include: arthralgia, and asthenia. See below for a comprehensive list of adverse effects.

Applies to topiramate: oral capsule, oral capsule extended release, oral tablet

Along with its needed effects, topiramate (the active ingredient contained in Topamax) may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor immediately if any of the following side effects occur while taking topiramate:

More common

• Any vision problems, especially blurred vision, double vision, eye pain, or rapidly decreasing vision
• burning, prickling, or tingling sensations
• clumsiness or unsteadiness
• confusion
• continuous, uncontrolled back-and-forth or rolling eye movements
• dizziness
• drowsiness
• eye redness
• generalized slowing of mental and physical activity
• increased eye pressure
• memory problems
• menstrual changes
• menstrual pain
• nervousness
• speech or language problems
• trouble in concentrating or paying attention
• unusual tiredness or weakness

Less common

• Abdominal or stomach pain
• fever, chills, or sore throat
• lessening of sensations or perception
• loss of appetite
• mood or mental changes, including aggression, agitation, apathy, irritability, and mental depression
• red, irritated, or bleeding gums
• weight loss

Rare

• Blood in the urine
• decrease in sexual performance or desire
• difficult or painful urination
• frequent urination
• hearing loss
• loss of bladder control
• lower back or side pain
• nosebleeds
• pale skin
• red or irritated eyes
• ringing or buzzing in the ears
• skin rash or itching
• swelling
• trouble breathing

Incidence not known

• Blistering, peeling, or loosening of the skin
• blisters in the mouth
• blisters on the trunk, scalp, or other areas
• bloating
• clay-colored stools
• constipation
• cough
• diarrhea
• increased rate of breathing
• joint or muscle pain
• pain or tenderness in upper abdomen or stomach
• red skin lesions, often with a purple center
• sores, ulcers, or white spots in the mouth or on the lips
• yellow eyes or skin

Get emergency help immediately if any of the following symptoms of overdose occur while taking topiramate:

Symptoms of overdose

• Decreased awareness or responsiveness
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• severe sleepiness
• unusual drowsiness, dullness, tiredness, weakness, or feeling of sluggishness

Some side effects of topiramate may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• Breast pain in women
• tremors

Less common

• Back pain
• chest pain
• constipation
• heartburn
• hot flushes
• increased sweating
• leg pain

Applies to topiramate: oral capsule, oral capsule extended release, oral tablet

Uncommon (0.1% to 1%): Bradycardia, sinus bradycardia, palpitations, hypotension, orthostatic hypotension, flushing, hot flush

Rare (less than 0.1%): Raynaud's phenomenon

Common (1% to 10%): Alopecia, rash, pruritus

Uncommon (0.1% to 1%): Anhidrosis, hypoesthesia facial, urticaria, erythema, pruritus generalized, rash macular, skin discoloration, dermatitis allergic, swelling face

Rare (less than 0.1%): Stevens-Johnson syndrome, erythema multiforme, skin odor abnormal, periorbital edema, urticaria localized

Frequency not reported: Toxic epidermal necrolysis, oligohidrosis

Postmarketing reports: Bullous skin reactions, pemphigus

Very common (10% or more): Nausea, diarrhea

Common (1% to 10%): Vomiting, constipation, abdominal pain upper, dyspepsia, abdominal pain, dry mouth, stomach discomfort, paresthesia oral, gastritis, abdominal discomfort

Uncommon (0.1% to 1%): Pancreatitis, flatulence, gastroesophageal reflux disease, abdominal pain lower, hypoesthesia oral, gingival bleeding, abdominal distension, epigastric discomfort, abdominal tenderness, salivary hypersecretion, oral pain, breath odor, glossodynia

Uncommon (0.1% to 1%): Erectile dysfunction, sexual dysfunction, renal calculus, intermenstrual bleeding, leucorrhoea, menorrhagia, vaginitis, amenorrhea, urinary tract infections, micturition frequency, urinary incontinence, dysuria

Postmarketing reports: Kidney stones, nephrocalcinosis

Common (1% to 10%): Anemia, epistaxis

Uncommon (0.1% to 1%): Leucopenia, thrombocytopenia lymphadenopathy, white blood cell count decreased, eosinophilia

Rare (less than 0.1%): Neutropenia

Rare (less than 0.1%): Hepatitis, hepatic failure, increase in liver enzymes

Postmarketing reports: Hepatic failure including fatalities

Common (1% to 10%): Hypersensitivity

Frequency not reported: Allergic edema, conjunctival edema

Very common (10% or more): Nasopharyngitis

Frequency not reported: Genital moniliasis

Very common (10% or more): Weight decreased

Common (1% to 10%): Anorexia, decreased appetite, weight increased

Uncommon (0.1% to 1%): Metabolic acidosis, hypokalemia, increased appetite, polydipsia

Rare (less than 0.1%): Acidosis hyperchloremic, blood bicarbonate decreased

Postmarketing reports: Hyperammonemia with and without encephalopathy

Metabolic Acidosis:

Generally, topiramate-induced metabolic acidosis occurs early in treatment; however, it can occur any time. Average decreases of serum bicarbonate of 4 mEq/L have been observed in adults receiving 400 mg/day and pediatrics receiving approximately 6 mg/kg/day. Values below 10 mEq/L have been rarely reported. In adult trials for adjunctive treatment of epilepsy, persistent serum bicarbonate decreases to less than 20 meq/L were reported in 32% of patients receiving 400 mg/day versus 1% of placebo-treated patients. In pediatric trials, adjunctive therapy yielded persistent decreases in serum bicarbonate of 67% for doses of approximately 6 mg/kg/day and 10% for placebo. In monotherapy trials for patients 6 to 15 years, the incidence of persistent decreases in serum bicarbonate was 9% for 50 mg per day and 25% for 400 mg per day. In adult migraine trials, persistent decreases in serum bicarbonate occurred in 44%, 39%, 23%, and 7% of patients receiving 200 mg/day, 100 mg/day, 50 mg/day, and placebo, respectively. In adolescent migraine trials, this was 77%, 27%, 30%, and 9% for those receiving 200 mg/day, 100 mg/day, 50 mg/day, and placebo, respectively.

Hyperammonemia:

The incidence of hyperammonemia (above the upper limit of normal) for adolescent patients receiving this drug for migraine prophylaxis was 26%, 14%, and 9% for doses of 100 mg, 50, mg, or placebo, respectively. Hyperammonemia with and without encephalopathy has been reported in the post-marketing period. Hyperammonemia appears to be more common when used concomitantly with valproic acid.

Common (1% to 10%): Arthralgia, muscle spasms, myalgia, muscle twitching, muscular weakness, musculoskeletal chest pain

Uncommon (0.1% to 1%): Joint swelling, musculoskeletal stiffness, flank pain, muscle fatigue

Rare (less than 0.1%): Limb discomfort

Very common (10% or more): Paraesthesia, somnolence, dizziness

Common (1% to 10%): Disturbance in attention, memory impairment, amnesia, cognitive disorder, mental impairment, psychomotor skills impaired, convulsion, coordination abnormal, tremor, lethargy, hypethesia, nystagmus, dysgeusia, balance disorder, dysarthria, intention tremor, sedation

Uncommon (0.1% to 1%): Depressed level of consciousness, grand mal convulsion, visual field defect, complex partial seizures, speech disorder, psychomotor hyperactivity, syncope, sensory disturbance, drooling, hypersomnia, aphasia, repetitive speech, hypokinesia, dyskinesia, dizziness postural, poor quality sleep, burning sensation, sensory loss, parosmia, cerebellar syndrome, dysesthesia, hypogeusia, stupor, clumsiness, aura, ageusia, dysgraphia, dysphasia, neuropathy peripheral, presyncope, dystonia, formication

Rare (less than 0.1%): Apraxia, circadian rhythm sleep disorder, hyperesthesia, hyposmia, anosmia, essential tremor, akinesia, unresponsive to stimuli

Most CNS adverse reactions can be classified into 3 categories: cognitive-related dysfunction (e.g. confusion psychomotor slowing, difficulty with concentration/attention, difficulty with memory, speech, or language problems, particularly word-finding difficulties); psychiatric/behavioral disturbances (e.g. depression or mood problems); and somnolence or fatigue. Most were mild to moderate in severity and frequently occurred in isolation. Rapid titration rate and higher initial dose was associated with a higher occurrence.

Common (1% to 10%): Vision blurred, diplopia, visual disturbance

Uncommon (0.1% to 1%): Visual acuity reduced, scotoma, myopia, abnormal sensation in eye, dry eye, photophobia, blepharospasm, lacrimation increased, photopsia, mydriasis, presbyopia

Rare (less than 0.1%): Blindness unilateral, blindness transient, glaucoma, accommodation disorder, altered visual depth perception, scintillating scotoma, eyelid edema, night blindness, amblyopia

Frequency not reported: Angle closure glaucoma, maculopathy, eye movement disorder

Very common (10% or more): Fatigue

Common (1% to 10%): Vertigo, tinnitus, ear pain pyrexia, asthenia, irritability, gait disturbance, feeling abnormal, malaise

Uncommon (0.1% to 1%): Deafness, deafness unilateral, deafness neurosensory, ear discomfort, hearing impaired, hyperthermia, thirst, influenza like illness, sluggishness, peripheral coldness, feeling drunk, feeling jittery, tandem gait test abnormal

Rare (less than 0.1%): Face edema, calcinosis, learning disability

Frequency not reported: Hypothermia, hyperthermia (associated with oligohidrosis)

Very common (10% or more): Somnolence (15%), memory loss (10%), depression

Common (1% to 10%): Depression, difficulty with concentration/attention, anxiety psychomotor slowing, altered mood, confusion, cognitive difficulty, bradyphrenia, decreased libido, expressive language disorder, disorientation, aggression, aggression, anger, abnormal behavior

Uncommon (0.1% to 1%): Suicidal ideation, suicide attempt, hallucination, psychotic disorder, hallucination auditory, hallucination visual, apathy, lack of spontaneous speech, sleep disorder, affect lability, restlessness, crying, dysphemia, euphoria, paranoia, perseveration, panic attack, tearfulness, reading disorder, flat affect, thinking abnormal, listlessness, middle insomnia, distractibility, early morning awakening, panic reaction, elevated mood

Rare (less than 0.1%): Mania, panic disorder, feelings of despair, hypomania

Antiepileptic drugs increased the risk of suicidal thoughts or behaviors when taken for any indication. Pooled analyses of 199 placebo-controlled clinical trials of 11 different antiepileptic drugs showed patients on antiepileptics had approximately twice the risk compared to placebo. In these trials (median duration 12 weeks; most less than 24 weeks), the estimated incidence rate of suicidal behavior or ideation was 0.43% compared to 0.24% which represents an increase of approximately 1 case for every 530 patients treated.

Common (1% to 10%): Nephrolithiasis, pollakiuria, dysuria

Uncommon (0.1% to 1%): Calculus urinary, urinary incontinence, hematuria, incontinence, micturition urgency, renal colic, renal pain

Rare (less than 0.1%): Calculus ureteric, renal tubular acidosis

In clinical trials, 1.5% of adult patients receiving this drug developed kidney stones (approximately 2 to 4 times more than expected). The incidence was higher in men. Kidney stone have been reported in pediatric patients taking this drug for epilepsy or migraine.

Common (1% to 10%): Bronchitis, rhinitis, dyspnea, epistaxis, nasal congestion, rhinorrhea, cough

Uncommon (0.1% to 1%): Dyspnea exertional, paranasal sinus hypersecretion, dysphonia