Tiredness, drowsiness, dizziness, loss of coordination, tingling of the hands/feet, loss of appetite, bad taste in your mouth, diarrhea, and weight loss may occur. Mental problems such as confusion, slowed thinking, trouble concentrating or paying attention, nervousness, memory problems, or speech/language problems may also occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.
Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.
Tell your doctor right away if any of these unlikely but serious side effects occur: signs of kidney stones (such as severe back/side/abdominal/groin pain, fever, chills, painful/frequent urination, bloody/pink urine).
A small number of people who take anticonvulsants for any condition (such as seizures, bipolar disorder, pain) may experience depression, suicidal thoughts/attempts, or other mental/mood problems. Tell your doctor right away if you or your family/caregiver notice any unusual/sudden changes in your mood, thoughts, or behavior including signs of depression, suicidal thoughts/attempts, thoughts about harming yourself.
Tell your doctor right away if any of these rare but serious side effects occur: rapid breathing, fast/slow/irregular heartbeat, bone pain, broken bones, loss of consciousness, unusual bleeding/bruising.
Rarely, topiramate may cause a very serious eye problem, generally within 1 month of starting treatment. If untreated, this eye problem can lead to permanent blindness. Therefore, get medical help right away if any of these side effects occur: sudden vision changes (such as decreased vision, blurred vision), eye pain/redness.
This medication can rarely cause a serious metabolic problem (high amount of ammonia in the blood), especially if you are also taking valproic acid. Tell your doctor right away if you experience sudden/unexplained tiredness, vomiting, or mental changes (such as decreased alertness).
A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.
In the US -
Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.