What do the letters and numbers on a pill mean?

The letters and numbers on a pill are its imprint code. In the US, almost every tablet and capsule must carry one, so that the pill, together with its color, shape and size, can be matched to one specific medicine, strength and manufacturer.

Why pills have imprints

US federal rules require an imprint on prescription, over-the-counter and homeopathic tablets and capsules. The goal is safety: doctors, pharmacists and poison centers can identify a pill quickly, for example after an accidental swallowing or an overdose, or when a medicine turns up without its bottle.

What the code tells you

An imprint doesn’t follow a universal system you can decode on your own. Each manufacturer chooses its own code and lists it in the drug’s official label. A typical imprint has:

• letters, a word or a logo that stands for the company
• numbers that stand for the product and its strength
• sometimes the drug’s name or its strength in milligrams

Because the code is set by the manufacturer, you need to look it up to know what it means. Our pill imprint search does this for you.

Other marks on pills

• Score lines are grooves that show where a pill can be split. Only split a pill if your pharmacist or doctor says it’s safe.
• Two-sided imprints: many pills carry part of the code on each side. Search both sides together.
• Pressed or printed: tablets usually have the code pressed into them, while capsules usually have it printed in ink.

Which pills have no imprint

A few kinds of medicine are exempt, including medicines compounded by a pharmacist, medicines used in clinical trials, medicines given only in hospitals, and pills too small or soft to imprint. Vitamins and dietary supplements aren’t covered by the rules either. A pill without an imprint can’t be identified safely. See pills with no imprint.

The imprint vs the NDC

The National Drug Code (NDC) is a different number. It’s printed on the bottle or box, not the pill, and identifies the company, the product and the package. If you have the packaging, an NDC lookup is the quickest way to see what the pills inside should look like.

Common questions

Can two different medicines have the same imprint?

It happens, for example when a company uses one code across several strengths, or when several companies sell the same pill. That’s why you should also check the color, shape and size.

Does a pill’s color tell you what it is?

No. The manufacturer chooses the color, and the same medicine can come in different colors from different companies. Only the imprint, checked with the color, shape and size, identifies a pill.

Why does my pill have a different imprint than last time?

Your pharmacy has probably switched to a different manufacturer. See why your refill looks different.

Do pills outside the US have imprints?

Many do, but the rules differ from country to country. Our database covers medicines sold in the US.