You don't need a perscription. Be careful, as one of the questions asked by customs regards drugs. I am not sure of the legality of bringing in medications to the US. Maybe someone else knows. In Belize, the clerk behind the counter was just yelling out drug names and prices. Seemed like being at a ballgame except instead of yelling peanuts! She was saying Prosac, Valuim, Retin A, etc..
Some medications you do need a RX for some you do not. Technically it is illegal to bring meds back to the states unless they were perscribed outside the US for a specific illness that occurred. IE developed strep while away needed an antibiotic. Saying that people do it all the time when going to both Mexico & Canada.