How to Read the NDC Number to Confirm the Correct Medication

Every time a pharmacist hands you a pill bottle, a nurse prepares an injection, or a doctor writes a prescription, there’s a hidden number on the label that could mean the difference between life and death. That number is the NDC-National Drug Code. It’s not just a barcode or a random string of digits. It’s the unique fingerprint of your medication. Get it wrong, and you could get the wrong drug, the wrong dose, or even a completely different medicine. In the U.S., over 12% of medication dispensing errors trace back to misreading the NDC. But if you know how to read it, you can stop those errors before they happen.

What Exactly Is an NDC Number?

The NDC is a 10-digit number printed on every prescription and over-the-counter medicine sold in the United States. It’s not made up by the pharmacy or the manufacturer-it’s assigned by the FDA. Every drug product, no matter how common, has its own unique code. That means two different strengths of the same drug, like 10mg and 20mg of fluoxetine, have completely different NDCs. Even the same drug in a bottle of 30 pills versus 100 pills gets a different code.

The NDC breaks down into three parts, each with a specific job:

• Labeler Code (first segment): Who made or packaged the drug. This is a 4-, 5-, or 6-digit number assigned by the FDA to the company-like Pfizer, Teva, or a local pharmacy that repacks pills.
• Product Code (second segment): What the drug is. This 3- or 4-digit number tells you the active ingredient, strength, and dosage form. For example, 3105 might mean 10mg capsules, while 4465 means 20mg capsules.
• Package Code (third segment): How it’s packaged. This 1- or 2-digit number tells you the size and type of container-like 01 for a 30-pill bottle, or 02 for a 100-pill bottle.

On the label, you’ll see it written like this: 00002-3105-01. But here’s the catch-this format isn’t always the same. The FDA allows three possible layouts: 4-4-2, 5-3-2, or 5-4-1. That means the hyphens can fall in different places. You can’t assume the format. You have to count the digits.

How to Read the NDC Step by Step

Verifying an NDC isn’t guesswork. It’s a process. Here’s how to do it right:

1. Find the NDC on the packaging. Look on the side of the bottle, the blister pack, or the box. It’s usually printed clearly, sometimes in a red circle as shown in FDA training materials. Don’t rely on the pharmacy label alone-always check the original manufacturer’s packaging.
2. Count the digits between hyphens. This tells you the format. If it’s 4 digits, then 4 digits, then 2 digits (like 1234-5678-90), it’s a 4-4-2 format. If it’s 5 digits, 3 digits, 2 digits (like 12345-678-90), it’s 5-3-2. If it’s 5 digits, 4 digits, 1 digit (like 12345-6789-0), it’s 5-4-1.
3. Compare each segment to the prescription. The labeler code should match the expected manufacturer. The product code must match the drug name, strength, and form-like 10mg tablet, not 20mg capsule. The package code should match the quantity ordered. If the script says 30 pills, the package code should reflect that.
4. Check the FDA’s NDC Directory. Go to the FDA’s website and search the 10-digit NDC. You’ll see the official drug name, manufacturer, strength, and approved uses. If the directory says the product is discontinued or doesn’t match the label, stop. Don’t dispense it.

One pharmacist in Arizona caught a fatal error when the NDC on the shelf read 00002-4465-01 (Prozac 20mg capsules), but the prescription was for 00002-3105-01 (Prozac 10mg capsules). The product code was the only difference-but that difference meant doubling the dose. The patient was at risk of serotonin syndrome. She caught it because she checked every digit.

Why the 11-Digit Format Matters

Here’s where things get tricky. While the label shows a 10-digit NDC, insurance systems, Medicare, and Medicaid require an 11-digit version for billing. That’s not a mistake-it’s a requirement. The 11-digit format is always 5-4-2. So if your label says 5-3-2 (like 12345-678-90), you have to add a zero to make it 12345-0678-90. If it’s 4-4-2 (like 1234-5678-90), you add a zero at the front: 01234-5678-90. If it’s 5-4-1 (like 12345-6789-0), you add a zero at the end: 12345-6789-00.

Getting this wrong means your claim gets rejected. Patients can’t get their meds. Pharmacies lose money. But more importantly, if you’re mixing up the 10-digit and 11-digit versions in your head, you might misread the product code. That’s how errors creep in.

A hospital tech in Oregon told Reddit he spends 15-20 minutes extra per shift just converting NDCs. He’s not alone. Over 60% of pharmacists report NDC format confusion at least once a month. The fix? Train your team. Use a conversion chart. Keep a printed reference near the counter. And never assume-always count.

Common Mistakes and How to Avoid Them

Even experienced staff slip up. Here are the top three errors-and how to stop them:

• Mixing up product code and package code. The product code tells you what the drug is. The package code tells you how many pills. If you see 00002-3105-01 and think 3105 is the quantity, you’re wrong. 3105 is the strength and form. 01 is the bottle size. Always verify the segment position.
• Assuming the same drug has the same NDC. If you refill a prescription and the bottle looks different, don’t assume it’s the same. Generic drugs from different manufacturers have different NDCs. Even the same manufacturer might change packaging. Always check the NDC, not the label design.
• Not verifying discontinued codes. In just nine months in 2023, the FDA deactivated over 8,500 NDCs. Some were recalled. Others were discontinued. If the NDC isn’t in the FDA’s current directory, it’s not approved. Don’t dispense it.

One of the most dangerous mistakes? Confusing two drugs with the same active ingredient but different inactive ingredients. The NDC doesn’t list fillers or dyes. So two versions of metformin might have the same NDC structure but different allergens. That’s why you still need to read the full label-even after checking the NDC.

What You Should Do Every Time

The American Society of Health-System Pharmacists says you must verify the NDC at three points:

1. When you receive the medication from the supplier.
2. When you prepare it for the patient.
3. Right before you hand it over.

That’s not extra work-it’s your safety net. Most hospitals require two people to verify high-risk drugs like insulin, chemotherapy, or blood thinners. That extra 37 seconds per check? It’s worth it. A single error can lead to hospitalization, legal action, or death.

Here’s a simple habit that works: Say the NDC out loud. "Labeler: zero-zero-zero-zero-two. Product: three-one-zero-five. Package: zero-one." Hearing it forces your brain to process it differently than just reading it. Studies show 78% of pharmacists who verbalize the NDC report fewer errors.

Tools and Resources

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

• FDAs NDC Directory (free, updated daily): Search by NDC, drug name, or manufacturer. It shows approval status, active ingredients, and marketing category.
• Mobile apps: The FDA has a free app for smartphones. Scan the barcode or type in the NDC. Instant verification.
• Pharmacy software: Most systems auto-convert NDCs to 11-digit billing format and flag mismatches. But don’t rely on automation alone. Always double-check.
• Hotline: If you’re stuck, call the FDA’s NDC hotline: 1-855-543-3784. They answer 24/7.

Some pharmacies pay for tools like AAPC Codify ($129/month), which links NDCs to electronic records and alerts you to changes. But even the free tools are enough if you use them consistently.

What’s Changing in 2025

The FDA is moving to a 12-digit NDC format by 2025. No more 4-4-2, 5-3-2, or 5-4-1. Everything will be standardized. That means less confusion, fewer billing errors, and better tracking across the supply chain. The Drug Supply Chain Security Act already requires NDC-based tracing for every package. The new system will make that even tighter.

But change brings friction. Small pharmacies worry about updating systems. Some say the transition will cost thousands. Still, the goal is clear: reduce errors. Right now, about 8.7% of pharmacy claims get rejected because of NDC format mistakes. That number should drop to near zero once the new system rolls out.

For now, the rules haven’t changed. The 10-digit NDC is still the law. And if you’re reading this, you’re holding the key to preventing mistakes. You don’t need to be a doctor. You don’t need to be a pharmacist. You just need to know how to count the digits.