- NDC codes uniquely identify every finished drug in the U.S.
- Each code has three segments – labeler, product, and package
- The FDA maintains and publishes NDC data through the NDC Directory and DailyMed
- Upcoming changes to a 12-digit standard will modernize the NDC system
The National Drug Code (NDC) provides transparency into finished drugs – helping stakeholders track, identify, and manage medications across the healthcare supply chain. This article explains what NDC codes are, how they’re created, and how they’re used throughout the healthcare ecosystem.
What is an NDC code?
An NDC code is a unique identifier that describes the manufacturer, drug (including strength and dose form), and package size for a medicinal product or drug. NDC codes are applied to “finished drugs” or “medicinal products” — medications and related supplies that are ready for use in humans or animals.
A finished drug is defined by the FDA as an article intended for use in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or function of the body of humans or animals.
The European Medicines Agency (EMA) defines a medicinal product as a substance or combination of substances intended to treat, prevent, or diagnose disease, or to restore, correct, or modify physiological functions through pharmacological, immunological, or metabolic action.
Together, these definitions establish the scope of what NDCs represent across the pharmaceutical landscape.
A brief history of NDC codes
NDC codes first appeared as nine-digit numbers in the 1960s. This early format laid the groundwork for future regulatory developments. The Drug Listing Act of 1972 made the ten-digit NDC a mandatory feature on drug product labeling.
In 2004, the FDA introduced a new requirement for drug labeling: each label had to include a barcode containing the NDC in unformatted form. This mandate, which became effective in 2006, further streamlined the identification and tracking of pharmaceutical products.
Understanding NDC formats
Currently, an NDC code can take the shape of a ten-digit number in one of three formats: 4-4-2, 5-3-2, or 5-4-1. Each format contains three segments that identify the labeler, product, and package size of a finished drug.
The FDA has proposed expanding the labeler code to six digits and standardizing all NDC codes to 12 digits.
How NDC codes are created and published
To create an NDC, a manufacturer, repackager, or distributor must first request an NDC labeler code from the FDA. This process is initiated through a Structured Product Labeling (SPL) submission, which is sent via the Electronic Submissions Gateway (ESG) or CDER Direct, a web-based system for submitting and managing product information.
The FDA then assigns the first segment of the NDC, consisting of four to six digits, to identify the labeler. Once the labeler code is assigned, the company determines the second and third segments of the NDC: the product code (drug, strength, and dosage form) and the package code (package size and type).
The labeler prepares an SPL XML file that includes comprehensive product details, such as active ingredients, dosage form, and route of administration, and labeling content like carton or container labeling and prescribing information. The assigned NDC is incorporated into this SPL, which is then submitted electronically via ESG or CDER Direct.
Upon receipt, the FDA validates the SPL for XML schema compliance and checks for all required data elements, including UNII codes for both active and inactive ingredients used in the finished product. The agency also verifies that the NDC format is correct.
After validation, the FDA publishes the NDC and SPL information in the NDC Directory, the official database of all listed drugs. Labeling content is also made available on DailyMed, which hosts the most detailed publicly accessible source of information about drugs and medicinal products.
Updates to these resources occur daily or weekly, ensuring that the data remains current and accessible to stakeholders across the healthcare ecosystem.
Accessing and using NDC data
Once an NDC code is published, it becomes a valuable resource for stakeholders across the healthcare ecosystem. Healthcare systems, payers, and data aggregators access this information through several channels:
- openFDA application programming interfaces (APIs), which provide NDC Directory and SPL data in JSON format
- Bulk SPL XML downloads from DailyMed, allowing organizations to ingest comprehensive drug labeling data directly
- Commercial databases like First Databank and Medi-Span, which enrich FDA data for clinical use
These systems leverage NDC and SPL data to support critical functions such as accurate EHR documentation, pharmacy dispensing, insurance billing, and drug utilization review.
An NDC effectively serves as the “currency” of the pharmaceutical realm – used by pharmacies, insurers, and providers to describe a finished medicinal product with the utmost precision.
How NDC codes interact with other coding systems
Because of their granularity, NDCs are used in several other coding and documentation systems.
RxNorm®: Maintained by the National Library of Medicine, RxNorm aggregates drug data from FDA sources and commercial databases, linking NDCs to RxNorm concepts (RxCUIs).
CVX & MVX (Vaccines): Vaccinations use CVX (vaccine type) and MVX (manufacturer) codes to document clinically interchangeable products without requiring NDC-level detail.
CPT & HCPCS: The Centers for Medicare & Medicaid Services (CMS) publishes quarterly crosswalks mapping multiple NDCs to a single HCPCS or CPT code for billing and reimbursement.
FDA Purple and Orange Books: The Orange Book lists therapeutically equivalent small-molecule drugs, while the Purple Book identifies biological products that are biosimilar or interchangeable.
Challenges and the future of NDC codes
The FDA has identified a future state where it may run out of labeler codes, prompting the proposal to expand all NDC codes to 12 digits. This change will have wide-ranging effects on systems that consume NDCs, and some industry stakeholders have raised concerns about barcode compatibility.
Several counterproposals have been suggested, including using alphanumeric labeler codes or fixed-length segments to fit within GTIN barcodes and streamline downstream processes.
Meanwhile, NDC codes are being assigned to human cells, and revolutionary new treatments like CAR-T therapies are being assigned NDC codes, pushing the boundaries of what we think of as “drugs” and “medicinal products.”
Why NDCs matter
As the cornerstone of drug identification for more than half a century, the NDC system supports transparency, traceability, and consistency throughout the drug supply chain. Its structure enables data interoperability across healthcare systems – from manufacturers to EHRs, pharmacies, and payers. As available treatments evolve and current systems reach their limitations, the humble NDC code of the 1970’s is sure to change, too.
By understanding how these codes are structured, assigned, and used, healthcare organizations can reduce errors, improve data integrity, and prepare for the next phase of digital drug management.
Now that you understand NDC codes, learn how pharma outsmarts data bottlenecks with clinical terminology.
RxNorm® is a registered trademark of the National Library of Medicine.
