The imprint code is one of the physical characteristics that a person can use to identify a pill, states the U.S. National Library of Medicine. This is because the Food and Drug Administration requires all over-the-counter and prescription drugs in the United States to have this imprint, explains Drugs.com.
The imprint on the drug is a letter, a number or a combination of letters and numbers. Some drugs also have logos, monograms and symbols, explains Drugs.com. The imprint helps patients, law enforcement officials and health care providers identify the ingredients, strength and manufacturer of a particular drug. Patients use the imprints to know what a drug is if they have dropped it, mixed it in a pill case or found it in their homes. Pills that do not have the imprint are usually vitamins, dietary supplements, foreign medication or illegal drugs.