What Is an NDC Number?

If you have looked closely at a medicine box or bottle in the United States, you have probably seen a string of numbers labelled "NDC". This guide explains what the National Drug Code is, how to read it, and how it differs from the imprint stamped on the pill itself.

A number for the package, not the pill

The NDC is a unique code that the FDA assigns to medicines marketed in the US. It identifies a specific product in a specific package — which is why it is printed on the outer carton, the bottle label and pharmacy paperwork, but never stamped on the tablet itself. When you need to identify a loose pill, the imprint is the tool; when you need to identify a packaged product — for a pharmacy system, an insurance claim or a recall — the NDC is the tool.

The three segments

An NDC is written in three parts, separated by dashes:

• Labeler code (the first segment, 4–6 digits) — identifies the company that makes, repackages or distributes the product.
• Product code (the middle segment, 3–4 digits) — identifies the specific medicine: its active ingredient, strength and dosage form, as listed by that labeler.
• Package code (the last segment, 1–2 digits) — identifies the package size or type, such as a bottle of 30 versus a bottle of 100.

Because the segments can be different lengths, the same code may be written in 4-4-2, 5-3-2, 5-4-1 and other configurations, and pharmacy systems often pad it to a fixed 11-digit format with leading zeros. Two packages of the same medicine, from the same labeler but in different bottle sizes, share the first two segments and differ only in the last.

NDC versus imprint

The two codes answer different questions. The imprint is on the pill, stays the same across package sizes, and is what you use to identify a tablet whose packaging is long gone. The NDC is on the packaging, changes with package size, and connects a product to pharmacy, billing and recall systems. One medicine from one labeler typically has one imprint but several NDCs — one per package type. That is why our pill pages list "NDC examples": they are the package codes recorded for that pill in the FDA data, not different versions of the pill.

What an NDC does not tell you

An NDC identifies a listed product; by itself it does not prove a package is genuine, in date, or safe, and the FDA notes that an NDC assignment is not the same thing as FDA approval of the drug. For the identity of a loose tablet or capsule, start with the imprint — and for anything you plan to rely on, confirm with a pharmacist.