Minimal abuse potential. Number of outpatient refills determined by prescriber. Some products (cough suppressants with small amounts of codeine, antidiarrheals containing paregoric, pregabalin) may be available without prescription to patients >18 yr of age.

The Drug Enforcement Agency (DEA), an arm of the United States Justice Department, classifies controlled substances according to five schedules, based on whether they have a currently accepted medical use in treatment in the United States, the potential for abuse and dependence liability (physical and psychological) of the medication, and likelihood of causing dependence when abused. Some states may have stricter prescription regulations. Physicians, dentists, podiatrists, and veterinarians may prescribe controlled substances. Nurse practitioners and physician assistants may also prescribe controlled substances with limitations that vary from state to state.