Topiramate is an anti-epileptic drug. They're used for a variety of things, including pain management, and generally after various other options have been exhausted. This is because they are quite serious business as meds go, they have a high side-effect profile. Keep an eye on how it affects you, and keep talking to your GP. You'll need to be think about whether a side-effect is a) completely intolerable, b) tolerable but only if it's short-term (e.g. you could live with it for a week or two as long as it goes away after that), c) might be tolerable if it were milder, or b) tolerable as it is. You can also ask the doctor how a side-effect is likely to progress, as they will hopefully know about that. For instance, when I was on Prozac for severe PMS, I felt numb and disconnected, which is particularly unpleasant when you're in a relationship (not sure if I could have coped if I were single). My GP said, "Right, that sort of side effect doesn't improve, and it'll happen with the whole group, so I'm taking you off it." Whereas with other side effects on other meds, she's told me that it'll likely pass in a few weeks if I hang in there. This is why it's important to keep up a good dialogue with your GP. Lots of people just take the med, then realise they don't like it due to side effects or because it's not doing anything useful, and quietly drop it without telling the GP anything at all! Well, if you do that, then how can the GP help you! Apologies if this is something you already know, by the way. I definitely had to learn it the hard way, and I know a lot of people who just don't do it.
In terms of personal experience, I haven't been on topiramate, but I've been on another anti-epileptic, gabapentin. I had a variety of side-effects, none truly horrific, I think it was moderate to severe, but it also wasn't doing a thing for the pain, so they weren't worth putting up with. They varied according to the dose I was on. I remember that I had word-finding difficulties at 1800mg that went away on a higher dose, but came back again on the way down. The main thing I learned is that you need to withdraw from this group very slowly, otherwise it can be really awful. I had such a horrendous time with withdrawal, despite being tapered off (with hindsight, going down by 300mg/week was too fast for me), that I am never touching that drug group again. But then I have severe ME/CFS and am very sensitive to meds. Still, it's worth being cautious about that.
I hope you manage to give it a good try and that it works out well for you, and if not, that you come off it without problems and manage to find a good alternative.