To identify a pill, a patient can enter the imprinted letters or numbers into a pill identifier, such as the one at Drugs.com. The Food and Drug Administration requires all prescription and over-the-counter medications in the United States to have imprints to aid identification.
Imprints are combinations of letters and numbers that allow a person to identify the active ingredient, dosage and manufacturer of the pill. A pill without an imprint may be a vitamin or dietary supplement, a foreign medication or an illicit drug, says Drugs.com. To avoid confusion, a patient should keep all medications in their original containers.