How to Read a Pill Imprint

Almost every prescription tablet or capsule sold in the United States carries a small code stamped, printed or embossed on its surface. That code is called the imprint, and it is the single most reliable way to identify a loose pill. This guide explains what an imprint is, where to look for one, and how to write it down correctly so an identifier tool can match it.

Why pills have imprints

Since 1995, US Food and Drug Administration (FDA) rules (21 CFR Part 206) have required most solid oral medicines — tablets and capsules — to carry an imprint that identifies the product and its maker or distributor. The rule exists for safety: if someone finds an unidentified pill, or mixes up two medicines, the imprint lets a pharmacist, doctor or poison control specialist work out exactly what it is. A code can be a company name or logo, a number, a letter–number combination, or a mix of these.

Step 1: Look at both sides

Pick the pill up under a good light and turn it over. Many tablets carry part of the code on the front and the rest on the back. Capsules often have one part printed on the cap and another on the body. Write down everything you can see, from both sides, before you search. If the pill is scored (it has a groove so it can be split), note that too — the score pattern is part of the description on the FDA label.

Step 2: Read the characters carefully

Imprints are small and easy to misread. Common mix-ups include:

• The letter O versus the number 0
• The letter I or L versus the number 1
• The letter S versus the number 5, and Z versus 2
• A logo or symbol that looks like a letter — many labels record these as part of the code

A magnifying glass, or zooming in with a phone camera, helps a lot. If a character could be read two ways, try both versions in the search.

Step 3: Add the colour and shape

An imprint on its own is not always unique. Short codes such as "5", "10" or "20" are shared by many different medicines. That is why our identifier also asks for the pill's colour and shape: a white round tablet and a blue oval capsule with the same code are different products, and the FDA label records colour, shape and size for exactly this reason. Always compare all of the characteristics — imprint, colour, shape and size — before treating a result as a match.

Step 4: Confirm before you rely on it

An online match means the pill matches the FDA label for a particular medicine. It is not a guarantee: look-alike and counterfeit pills can copy real imprints. Never take a pill just because it matched online. Show it to a pharmacist, who can confirm the identification in person. If someone may have swallowed an unknown pill, call Poison Control on 1-800-222-1222 (US) right away.

Ready to try? Enter the imprint exactly as you read it into the pill identifier on our home page — spaces do not matter, and you can add colour and shape to narrow the results.