Everyone needs different dosages. The first neurologist who put me on topamax swore up and down it was NECESSARY i go all the way up to 100mg. omg i have never been so sick from a medication...not only was i horribly stupid (my bf would joke he need to spoon feed me on that dosage) but i was so horribly nauseous that as soon as i took topamax i had to go to bed b/c i was so dizzy and sick. After going to a neurologist who specializes in migraines (and whose motto is "low and slow" with medication dosages), we found that my ideal dosage on topamax is 50 mg. Keep track of how you're feeling. Be careful not to drive if at all possible when you're feeling this way! And communicate along the way with your dr. Thats the best advice I have. Good luck :)...this too, shall pass.
Sarah