i know as a kid raised on allergy/asthma drugs, they can easily turn you into a different person, take away your self-control, and make you extremely emotionally sensitive to noise, light, touch, etc.
Also, if he's NOT acting this way to anyone else, he may just be mad at you. This is NOT a condemnation of your mothering, simply a thought for consideration. Is he left in daycare, with another caregiver, left alone to play for long periods of time, is there a huge change in his life (like are you pregnant, recent move, etc), or do you have to ignore him for prolonged periods while in the house with him in order to get work/etc done? If so, he may be trying to express to you that he is hurt and angry, or even just confused by this. You may want to seek to understand his emotions and see if that's not the culprit also...
could it be something he's learned from another child? My son learned most of his negative behavior from other kids in daycare....
Also, boys play MUCH rougher than girls! And that doesn't stop. Could you think of ways to make that fun? water gun fights, pillow fights, wrestling matches, etc....
Good luck! :)