Dizziness, drowsiness, dry mouth, difficulty sleeping, tiredness, tingling of the hands/feet, constipation, and metallic taste may 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 you have any serious side effects, including: temporary difficulty concentrating/finding words/remembering things, signs of kidney stones (such as painful urination, fever, chills, pink/bloody urine), rapid breathing, fast/slow/irregular heartbeat, bone pain/broken bones, loss of consciousness, change in sexual ability/interest, unusual bleeding/bruising.
A small number of people who take anticonvulsants for any reason (such as seizure, 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.
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).
Get medical help right away if you have any very serious side effects, including: severe headache, trouble speaking, seizure, weakness on one side of the body.
This drug may rarely cause serious (sometimes fatal) lung or heart problems (pulmonary hypertension, heart valve problems). The risk may increase with longer use of this medication and use of other appetite-suppressant drugs/herbal products along with this drug. Stop taking this medication and get medical help right away if you have any very serious side effects, including: chest pain, difficulty breathing with exercise/decreased ability to exercise, fainting, swelling of the legs/ankles/feet.
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.