How to Read the NDC Number to Confirm the Correct Medication

Every year, over 1.2 million medication errors happen in the U.S. - and nearly 9% of them come from someone misreading an NDC number. That’s not a small mistake. It’s the difference between a patient getting their prescribed 20mg tablet and accidentally receiving a 40mg capsule. The NDC number is your last line of defense against these errors. If you work in a pharmacy, hospital, or even manage medications at home, learning how to read it properly isn’t optional - it’s life-saving.

What Exactly Is an NDC Number?

The National Drug Code, or NDC, is a 10-digit number printed on every prescription and over-the-counter medicine sold in the United States. It’s not just a barcode or a serial number. It’s a structured code that tells you exactly what drug you’re holding - down to the manufacturer, strength, dosage form, and package size.

The NDC was created by the FDA in 1972 under the Drug Listing Act. Today, over 150,000 active drug products are listed in the FDA’s official directory. Each one has a unique NDC. That means if two pills look identical, but their NDCs are different, they’re not the same drug. And that’s why you must read it correctly.

The Three Segments of the NDC

Every NDC number is split into three parts, separated by hyphens. Think of it like a phone number: area code, exchange, and line number. Each part has a specific meaning.

• Labeler Code (first segment): 4 to 6 digits. This identifies the company that made or repackaged the drug. For example, 00002 is Eli Lilly. 00003 is Pfizer. This segment tells you who’s responsible for the product.
• Product Code (second segment): 3 to 4 digits. This is the most important part. It tells you the active ingredient, strength, and dosage form. For instance, 3105 might mean “fluoxetine 10mg capsule.” Change one digit, and you’re looking at a different drug - maybe 4465, which is fluoxetine 20mg capsule. That’s a 100% stronger dose.
• Package Code (third segment): 1 to 2 digits. This tells you the size and type of package. 01 could mean a bottle of 30 tablets. 02 could mean a bottle of 100. 10 might mean a box of 10 blister packs.

These segments are never the same length. You’ll see three common formats: 4-4-2, 5-3-2, or 5-4-1. That means the number of digits in each segment can vary. Don’t assume it’s always the same.

How to Read an NDC Step by Step

Here’s how to verify a medication using the NDC - whether you’re a pharmacist, technician, or caregiver.

1. Find the NDC on the packaging. Look on the side or bottom of the bottle, box, or blister pack. It’s usually printed clearly, sometimes in a red circle as shown in FDA training materials.
2. Count the digits between hyphens. Is it 4-4-2? 5-3-2? 5-4-1? Write it down. This tells you the format.
3. Match the labeler code. Does it match the brand or generic manufacturer listed on the prescription? If the script says “generic fluoxetine” but the NDC is from a company you don’t recognize, double-check.
4. Verify the product code. This is where most errors happen. Compare the product code to the prescription. Is it 3105 (10mg) or 4465 (20mg)? Don’t rely on the drug name alone. Two different product codes can have the same brand name but different strengths.
5. Check the package code. Did the doctor order 30 tablets? Does the NDC show a package code for 30? If it says 01 (30) but you get a bottle labeled 02 (100), that’s a red flag.
6. Use the FDA’s NDC Directory. Go to fda.gov/fda-ndc-directory and type in the full 10-digit NDC. It will show you the exact drug name, strength, dosage form, and manufacturer. If what you see doesn’t match what’s on the label, stop. Don’t dispense it.

Why the 11-Digit Billing Format Matters

Here’s a hidden trap: the NDC on the bottle is 10 digits. But when you bill insurance - Medicare, Medicaid, or private plans - you must use an 11-digit version in the 5-4-2 format.

That means you have to add a zero somewhere. But where?

• If the format is 4-4-2 → Add a zero at the start of the labeler code → becomes 5-4-2
• If the format is 5-3-2 → Add a zero in the product code → becomes 5-4-2
• If the format is 5-4-1 → Add a zero at the end of the package code → becomes 5-4-2

Get this wrong, and your claim gets rejected. But more importantly, if you confuse the 10-digit label with the 11-digit billing version, you might misread the product code. A pharmacist in Arizona once gave a patient 20mg of Prozac instead of 10mg because she misread the 5-3-2 NDC as 5-4-2 and thought the product code was “03105” instead of “3105.” The extra zero changed everything.

Real-World Mistakes and How to Avoid Them

Here’s what goes wrong in real life:

• Mixing up product and package codes: A tech sees “02” at the end and thinks it’s the strength. It’s not. It’s the bottle size.
• Assuming all NDCs are the same format: A new tech sees a 5-4-1 and assumes it’s 5-4-2. They don’t convert it. Claim gets denied.
• Not checking discontinued codes: The FDA deactivates about 8,500 NDCs a year. If you’re using an old label or outdated database, you might be dispensing a drug that’s no longer approved.
• Ignoring generic equivalents: One drug can have 10 different NDCs because 10 different companies make it. You can’t assume they’re interchangeable unless you check the active ingredient and strength.

Best practice? Always say the NDC out loud during double-checks. “Labeler zero-zero-zero-zero-two, product three-one-zero-five, package zero-one.” Hearing it makes mistakes obvious.

Tools That Help

You don’t have to memorize every NDC. Use these tools:

• FDA’s NDC Directory (free): Search by NDC, drug name, or manufacturer. Updated daily.
• Mobile apps: The FDA has an official app. So do major pharmacy chains.
• Electronic Health Record (EHR) systems: Most modern systems auto-convert NDCs and flag mismatches.
• Two-person verification: For high-risk drugs like insulin, chemotherapy, or blood thinners, two people must confirm the NDC before dispensing. This adds 37 seconds per check - but cuts errors by over 60%.

The Bigger Picture: Why This Matters

The NDC isn’t just paperwork. It’s part of the Drug Supply Chain Security Act (DSCSA), which requires every drug package to be tracked electronically from manufacturer to patient. By 2025, the FDA plans to move to a 12-digit NDC format - eliminating all format variations. That’s good. It means fewer chances for human error.

But until then, the current system depends on you. Every pharmacist, nurse, and pharmacy tech who reads an NDC correctly is helping prevent a medication error. The American Society of Health-System Pharmacists says NDC verification must happen at three points: when you receive the drug, when you prepare it, and right before you give it to the patient.

And it works. One hospital in Ohio cut its medication errors by 41% in six months just by training staff to verbalize the NDC segments during checks.

Frequently Asked Questions

Next Steps

If you’re new to handling medications, spend 15 minutes today looking up five NDCs in the FDA’s directory. Type them in. See what the results show. Compare them to real bottles. You’ll start seeing patterns.

If you’re in a pharmacy, ask your manager for a quick NDC verification refresher. Many hospitals offer 10-minute training videos. Watch one. Share it with your team.

And if you’re a caregiver managing medications at home? Keep a printed list of your loved one’s NDCs. Write them down. Store them in a folder. When a new prescription comes in, compare the NDC on the bottle to your list. It takes 30 seconds. It could save a life.