Can topiramate cause diarrhea?
Yes. Diarrhea is a known possible side effect of topiramate. [1]
What does topiramate-related diarrhea usually feel like?
When it happens, diarrhea can range from mild, looser stools to more frequent, watery bowel movements. Because topiramate can affect the gastrointestinal tract in some people, stool changes may begin after starting the medication or after a dose increase. [1]
What should you do if you get diarrhea on topiramate?
If diarrhea is mild, clinicians often recommend monitoring symptoms, staying hydrated, and contacting the prescriber if it persists or worsens. If diarrhea becomes severe (for example, very frequent watery stools), leads to dehydration, or is accompanied by fever or significant abdominal pain, seek urgent medical care. (This is important because severe diarrhea can become dangerous quickly.) [1]
When to suspect something else
Diarrhea has many causes beyond medication, including infections, food-related illness, and other drugs. If symptoms are severe, last more than a few days, or come with red-flag symptoms (fever, blood in stool, dehydration), a clinician should evaluate you for non–topiramate causes. [1]
Source
[1] https://www.drugs.com/sfx/topiramate-side-effects.html