What Are Medicinal Products? FDA Categories and Requirements

Under federal law, a drug is any product intended to diagnose, cure, mitigate, treat, or prevent disease, or intended to affect the structure or function of the body — and also any product listed in an official pharmacopeia such as the United States Pharmacopoeia. That definition, set out in 21 U.S.C. § 321(g)(1), is what the FDA uses to decide whether a product falls under its drug authority, and the answer to the question of what is a drug under FDA rules turns far more on how a product is marketed than on what is inside it.¹

Intended Use Is the Trigger

The operative word in the statute is “intended.” A manufacturer’s claims, labeling, advertising, and promotional materials are what pull a product into drug regulation. A skin cream sold as a moisturizer is a cosmetic. The same cream sold as an eczema treatment is a drug. A dried herb sold as a food is a food; the moment someone promotes it as a cancer treatment, it becomes an unapproved drug.

Two chemically identical products can sit in entirely different regulatory categories based on nothing but the words on the label and website. This is why disputes over whether something “is” a drug are usually not chemistry disputes. They are marketing disputes.

How Drugs Differ From Supplements and Cosmetics

Because intended use controls, the most common consumer confusion is the line between drugs and dietary supplements. A dietary supplement is a product containing vitamins, minerals, herbs, amino acids, or similar ingredients that is intended to supplement the diet and is labeled as a supplement.² Supplements are regulated as a category of food and do not need FDA approval before going to market.

What a supplement can say about itself is the boundary. A label may make a structure/function claim — “calcium builds strong bones” — because it describes an effect on a normal body function. A disease claim, such as treating osteoporosis, is not allowed on a supplement. If the label crosses that line, the product legally becomes an unapproved drug and is subject to enforcement.³ Any supplement carrying a structure/function claim must also carry a disclaimer stating that the FDA has not evaluated the claim and that the product is not intended to diagnose, treat, cure, or prevent any disease.⁴

Homeopathic products sit in a strange spot. They technically meet the federal drug definition because they appear in the Homoeopathic Pharmacopoeia, yet they are sold without the premarket approval conventional drugs go through. The FDA uses a risk-based enforcement approach and prioritizes action against homeopathic products that pose the greatest public health risk.⁵ Most low-risk homeopathic products stay on shelves without having proven they work.

Prescription Versus Over-the-Counter

Once a product is classified as a drug, the next question is whether a consumer can buy it directly or needs a prescriber. The Durham-Humphrey Amendment, codified at 21 U.S.C. § 353(b), sets that line. A drug is prescription-only if its toxicity, potential for harm, or the way it must be used makes it unsafe without professional supervision.⁶ Prescription drugs must carry the “Rx only” symbol; a drug that should have it but doesn’t is legally misbranded.⁷

Over-the-counter drugs are those the FDA has determined to be safe and effective for consumers to use without a doctor, as long as they follow the label directions. The FDA regulates OTC ingredients and uses through administrative orders, and can expedite that process when a drug poses an imminent hazard or needs urgent label changes to reduce serious risk.⁸ Moving a drug from prescription to OTC status takes substantial evidence that an average consumer can self-diagnose the condition, choose the product correctly, and use it safely without a professional catching mistakes.

Biologics

Biologics are drugs made from living sources rather than through chemical synthesis. The Public Health Service Act defines a biological product as a virus, serum, toxin, antitoxin, vaccine, blood component, protein, or similar product used for preventing, treating, or curing disease.⁹ Vaccines, gene therapies, and monoclonal antibodies all fall in this category.

Because biologics come from living systems, they are sensitive to manufacturing conditions in ways conventional pills are not. Slight changes in temperature, contamination, or production methods can alter the final product in ways testing alone may not catch. Biologics follow a separate licensing pathway: manufacturers file a Biologics License Application (BLA) covering manufacturing processes, chemistry, pharmacology, and clinical data.¹⁰ Each package must carry the product name, the manufacturer’s license number, and the expiration date.⁹

Controlled Substances

Some drugs face an added layer of regulation on top of the FDA’s. The Controlled Substances Act assigns drugs with abuse potential to one of five schedules based on abuse potential, accepted medical use, and likelihood of dependence.¹¹

Schedule I: high abuse potential, no accepted medical use, not accepted as safe under medical supervision. Heroin and LSD are examples.
Schedule II: high abuse potential with accepted medical use and severe dependence risk. Oxycodone, fentanyl, and amphetamine sit here.
Schedule III: lower abuse potential than Schedule II, moderate or low physical dependence risk. Includes certain codeine formulations and anabolic steroids.
Schedule IV: low abuse potential relative to Schedule III. Includes alprazolam, diazepam, and lorazepam.
Schedule V: lowest abuse potential, mostly preparations with limited amounts of certain narcotics, such as low-dose codeine cough preparations.

The DEA, not the FDA, controls scheduling decisions and enforces prescribing, dispensing, and record-keeping rules for controlled substances.¹² Schedule II drugs, for example, cannot be refilled and require a new prescription each time. Doctors who prescribe controlled substances need a separate DEA registration in addition to their state medical license.

What Being a Drug Requires

Premarket Approval

Before a new drug can legally be sold in the United States, the manufacturer has to show it is safe and effective through a formal application. Conventional drugs go through a New Drug Application (NDA); biologics go through a BLA. An NDA must include data across chemistry, pharmacology, biopharmaceutics, and clinical trials, with trial results showing the drug works for its claimed use and that its benefits outweigh its risks at the proposed dose.¹⁰

Generic drugs use a shorter path called the Abbreviated New Drug Application (ANDA). A generic applicant does not repeat the safety and efficacy trials; it must show that its product has the same active ingredient, strength, and dosage form as the reference brand-name drug and is bioequivalent to it.¹⁰

For serious conditions, the FDA offers programs that shorten the timeline without lowering the evidence bar: Fast Track for drugs meeting an unmet medical need, Breakthrough Therapy for drugs showing substantial improvement over existing treatments in early evidence, and Priority Review, which cuts the FDA’s target review time to six months for drugs offering significant improvement in safety or effectiveness for a serious condition. A drug still has to prove safety and efficacy; these designations reduce time to patients, not the standard.¹³

Manufacturing Standards

Every drug sold in the United States must be produced under Current Good Manufacturing Practice (cGMP) standards. The regulations in 21 CFR Parts 210 and 211 set minimum requirements for the methods, facilities, and controls used in manufacturing, processing, packing, and holding drugs.¹⁴ A drug produced in a facility that fails to meet cGMP is legally adulterated even if the finished product tests clean.¹⁵ Quality has to be built into the process; end-testing alone is not enough.

Facilities that make drugs for the U.S. market, whether domestic or foreign, must register with the FDA within five business days of starting operations and renew that registration annually between October 1 and December 31.¹⁶ Registration by itself is not FDA approval; it puts the facility on the agency’s radar for inspection. Violations can bring warning letters, injunctions, and criminal penalties under 21 U.S.C. § 333.¹⁷

Labeling

What appears on a drug’s label is not a marketing decision. Federal regulations prescribe format, content, and even legibility.

OTC products must carry a standardized “Drug Facts” panel listing active ingredients, purposes, uses, warnings, directions, and inactive ingredients in a specific order. The text has to be in a single easy-to-read type style with at least 0.5-point spacing between lines and no more than 39 characters per inch.¹⁸

Prescription drugs include a professional package insert covering clinical pharmacology, approved uses, dosage, trial results, and storage. When the FDA determines a drug carries a risk of death or serious injury, it can require a boxed warning at the top of the prescribing information: the heading “WARNING” in uppercase, a brief explanation of the risk, and a cross-reference to the full detail elsewhere on the label.¹⁹ Introducing or delivering a misbranded drug into interstate commerce is a prohibited act under 21 U.S.C. § 331.²⁰

Most oral medications also require child-resistant packaging under the Poison Prevention Packaging Act. That covers all oral prescription drugs, all oral controlled substances, and specific OTC ingredients including acetaminophen products containing more than one gram per package, ibuprofen products containing 1,000 mg or more, iron supplements with 250 mg or more of elemental iron, and diphenhydramine products exceeding 66 mg.²¹ A few narrow exceptions exist, such as sublingual nitroglycerin. Consumers who cannot open child-resistant containers can ask their pharmacist for non-compliant packaging, but the default is protective.

Post-Market Safety

Approval is not the end of regulation. The clinical trials backing an NDA or BLA involve thousands of patients at most, so rare side effects, long-term risks, and drug interactions often surface only after millions of people are using the product.

Manufacturers must report adverse drug experiences to the FDA on an ongoing basis. Any event that is both serious and unexpected has to be reported within 15 calendar days of the manufacturer first learning about it.²² Less urgent events go into periodic safety updates, filed quarterly for the first three years after approval and annually after that.²³ If a manufacturer fails to meet those obligations, the FDA can withdraw approval and pull the drug entirely.

When new safety concerns appear, the FDA can require labeling changes, restrict a drug’s use, or push for a recall. Recalls are typically voluntary; the FDA has mandatory recall authority for controlled substances when there is a reasonable probability of serious harm or death. Recalls fall into three classes: Class I where use of the product is reasonably likely to cause serious health consequences or death; Class II where exposure may cause temporary or reversible effects, or where the probability of serious consequences is remote; and Class III where exposure is not likely to cause adverse health consequences.²⁴

Buying Drugs From Outside the United States

Because being an FDA-regulated drug means being an FDA-approved drug, buying prescription medication from abroad is generally illegal. Foreign products typically have not gone through FDA approval. The FDA does exercise enforcement discretion for personal importation in limited situations. For a drug treating a serious condition, importation may be allowed if no effective domestic treatment is available, the product is not being commercially promoted to U.S. residents, the quantity does not exceed a three-month supply, and the consumer provides the name of a U.S.-licensed doctor overseeing their treatment.²⁵

The FDA will refuse importation if the product is on an import alert for prior violations, the shipment looks intended for commercial distribution, or the product appears to present a serious health risk. Controlled substances face additional DEA scrutiny.²⁵ Enforcement discretion is not a legal right, and relying on it for ongoing medication access carries real risk.

1
Office of the Law Revision Counsel. 21 USC 321 – Definitions Generally
2
Office of the Law Revision Counsel. 21 USC 321 – Definitions Generally
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U.S. Food and Drug Administration. Structure/Function Claims
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U.S. Food and Drug Administration. Questions and Answers on Dietary Supplements
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U.S. Food and Drug Administration. Homeopathic Drug Products Guidance for FDA Staff and Industry
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Office of the Law Revision Counsel. 21 USC 353 – Exemptions and Consideration for Certain Drugs, Devices, and Biological Products
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GovInfo. 21 USC 353
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U.S. Food and Drug Administration. Frequently Asked Questions – OTC Monographs at FDA
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Office of the Law Revision Counsel. 42 USC 262 – Regulation of Biological Products
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U.S. Food and Drug Administration. Types of Applications
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Office of the Law Revision Counsel. 21 USC 812 – Schedules of Controlled Substances
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Drug Enforcement Administration Diversion Control Division. Controlled Substance Schedules
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U.S. Food and Drug Administration. Fast Track, Breakthrough Therapy, Accelerated Approval, Priority Review
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eCFR. 21 CFR Part 210 – Current Good Manufacturing Practice in Manufacturing, Processing, Packing, or Holding of Drugs General
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Office of the Law Revision Counsel. 21 USC 351 – Adulterated Drugs and Devices
16
U.S. Food and Drug Administration. Drug Establishments Current Registration Site (DECRS)
17
Office of the Law Revision Counsel. 21 USC 333 – Penalties
18
eCFR. 21 CFR Part 201 – Labeling
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eCFR. 21 CFR 201.57 – Specific Requirements on Content and Format of Labeling for Human Prescription Drug and Biological Products
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Office of the Law Revision Counsel. 21 USC 331 – Prohibited Acts
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eCFR. Poison Prevention Packaging
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eCFR. 21 CFR 314.80 – Postmarketing Reporting of Adverse Drug Experiences
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eCFR. 21 CFR 314.80 – Postmarketing Reporting of Adverse Drug Experiences
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U.S. Food and Drug Administration. Recalls Background and Definitions
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U.S. Food and Drug Administration. Personal Importation