U.S. residents entering the United States at international land borders who are carrying a validly obtained controlled substance (other than narcotics such as marijuana, cocaine, heroin, or LSD), are subject to certain additional requirements. If a U.S. resident wants to bring in a controlled substance (other than narcotics such as marijuana, cocaine, heroin, or LSD) but does not have a prescription for the substance issued by a U.S.-licensed practitioner (e.g., physician, dentist, etc.) who is registered with, and authorized by, the Drug Enforcement Administration to prescribe the medication, the individual may not import more than 50 dosage units of the medication into the United States. If the U.S. resident has a prescription for the controlled substance issued by a DEA registrant, more than 50 dosage units may be imported by that person, provided all other legal requirements are met.