I checked another thread and it said you are allowed to bring back a 90 day supply, but according to the US Customs Web site...
"The Federal Food, Drug, and Cosmetic Act prohibits persons from importing into the U.S. any prescription drug that has not been approved for sale by the United States Food and Drug Administration (FDA), or which is adulterated or misbranded within the meaning of the Act. Moreover, in those instances where a U.S. manufacturer makes an FDA-approved prescription drug and sends it abroad, the Act also prohibits any person other than the original manufacturer from importing the drug back into the U.S. Thus, in virtually all instances, individual citizens are prohibited from importing prescription drugs into the U.S."
Any insight?