Hi luluk,
If I were in your place I would leave the dosage of the topiramate right where it is now. By lowering or increasing the dosage it can sometimes mess up a persons system causing them to have seizures. If your son is still seizure free the less meds he's on the better off he will be. When I was 10 yrs. old my neuro had me on 5 different drugs and I was taking 106 pills a week. This really messed me up physcially causing me to have more seizures. I wouldn't want that to happen to your son or anyone. Take my word and keep the dosage right where it is unless seizures start up. Take care and May God Bless You and Your Family!

Sue