Topamax and daytime fatigue / tiredness?

Yes very common at the start but as WildcatVet has said for most the people I have heard from it does go away with continued use sometimes much sooner, Also very Important to try and take your dose's close to the same time every day this way you keep the right level and your body gets used to it sooner and hopefully the side effects go away faster.

Hi, again, Sphynxx! Yes, you guessed it ~ drowsiness and fatigue are common side effects of Topamax (and if you ask me why I can only say because). The titration period for Topamax, though, is generally about 5-8wks so there's a very good chance these effects will not persist much longer.
You're taking it at night right? Could you try taking it earlier in the evening and allowing for an extra hour or two of sleep?
Let your doctor know for sure but you are probably in the home stretch. Hang in there because you're doing great.
Happy Holidays, WCV