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FD&C Act §201(h) — The Legal Definition

The Federal Food, Drug, and Cosmetic Act (FD&C Act), codified at 21 U.S.C. § 301 et seq., is the primary federal statute governing medical devices in the United States. Section 201(h) [21 U.S.C. § 321(h)] contains the foundational definition of "device."

The three recognition/intended use bases​

The definition establishes three alternative bases for meeting the device definition:

Basis 1 — USP/NF recognition​

An article recognised in the official National Formulary (NF) or the United States Pharmacopeia (USP) is included within the definition. This basis is rarely relied upon for modern device classification — it exists primarily for historical continuity with earlier drug/device compendial articles.

Basis 2 — Disease-related intended use​

An article intended for use in the diagnosis of disease or other conditions, or in the cure, mitigation, treatment, or prevention of disease in humans or animals. This is the most commonly invoked basis and covers the vast majority of regulated medical devices.

Basis 3 — Body structure/function intended use​

An article intended to affect the structure or any function of the body of humans or animals. This extends the definition beyond disease-specific applications to encompass devices like orthopaedic implants, contraceptive devices, and cosmetic surgery instruments.

The chemical action exclusion​

An article meeting Basis 2 or 3 is not a device if it achieves its primary intended purpose through:

  • chemical action within or on the body; or
  • metabolism — i.e., it must be metabolised to achieve its purpose.

This exclusion carves out drugs and metabolically-active products. Note that an article may be "assisted" in its function by chemical action without losing its device status (for example, drug-eluting stents are devices with a drug component).

Key terms defined​

TermSignificance
Intended useDriven by labelling and promotional claims — not by actual clinical use
LabellingBroader than the label — includes all written, printed, or graphic matter accompanying the device
Component partA device part that becomes part of another device
AccessoryAn article intended to support, supplement, or complement a parent device

The intended use doctrine in enforcement​

FDA's intended use doctrine means that:

  • Labelling changes the regulatory status of a product — the same physical article can be a device, drug, or cosmetic depending on its claims.
  • Off-label promotion can create an implied intended use that triggers FDA jurisdiction even if the labelling appears neutral.
  • Post-market statements by company representatives can alter the declared intended use and create regulatory exposure.

Device vs. drug determination​

When a product has both device and drug characteristics, FDA applies a primary mode of action (PMOA) analysis:

  1. If the PMOA is device-like → regulated primarily as a device (CDRH)
  2. If the PMOA is drug-like → regulated primarily as a drug (CDER)
  3. If the PMOA cannot be determined → regulated by the centre with the most relevant expertise

Combination products are formally assigned via the Office of Combination Products (OCP) under 21 CFR Part 3.

Official resources​