How to read a drug label

What is a drug product label?

A drug product label (also called prescribing information or package insert) is the official FDA-reviewed document that accompanies every approved drug. It is the authoritative source of clinical information for a specific product and must be accurate, balanced, and evidence-based.

Labels are publicly available on DailyMed and Drugs@FDA. The structure follows FDA's physician labelling rule (PLR), which organises content under standardised section headers. EU equivalents — called Summary of Product Characteristics (SmPC) — are hosted on the EMA medicines database.

Brand name vs. International Nonproprietary Name

Every drug has two names at the top of its label. The proprietary (brand) name is the manufacturer's trademark (e.g., Advil, Nurofen). The non-proprietary name — called the INN or USAN — is the generic scientific name (e.g., ibuprofen).

The WHO INN programme assigns INNs to ensure global consistency. The US equivalent, USAN (United States Adopted Name), is maintained jointly by the AMA, USPC, and APhA. When writing clinical notes or prescriptions, always use the INN to avoid confusion between branded generics.

Indications and usage

The Indications and Usage section defines the approved condition(s) the drug is authorised to treat, prevent, or diagnose, along with the approved patient population. If the indication is limited (e.g., only certain disease stages or genotypes), this is specified here.

Use beyond these stated conditions is considered off-label. Off-label prescribing is legal, but FDA cannot require manufacturers to study or disclose off-label uses. The FDA guide to off-label use has more context.

Dosage and administration

This section specifies the approved doses, dosing intervals, routes of administration (oral, IV, topical, etc.), and instructions for preparation and handling. Importantly, it includes dose modifications for special populations: renal impairment, hepatic impairment, paediatric patients, and geriatric patients.

For pharmacokinetic rationale behind dose adjustments, see the Clinical Pharmacology section of the same label, or cross-reference our glossary entries on half-life, bioavailability, and volume of distribution.

Warnings and precautions

Safety information occupies several subsections:

Clinical Pharmacology (PK/PD)

The Clinical Pharmacology section is the most scientifically rich part of the label. It covers:

• Mechanism of action — how the drug exerts its effect at molecular/cellular level
• Pharmacodynamics — dose/concentration–response relationships
• Absorption — Tmax, Cmax, bioavailability (F) — see our bioavailability guide
• Distribution — volume of distribution (Vd), plasma protein binding — see Vd glossary
• Metabolism — CYP enzymes, active metabolites, first-pass effect
• Elimination — half-life, renal/biliary clearance — see half-life glossary
• Special populations — paediatrics, geriatrics, renal/hepatic impairment, sex, race

PK parameters are sourced from clinical studies and presented as mean ± SD or geometric mean. For more on CYP-mediated metabolism and drug interactions, the FDA CYP substrate/inhibitor/inducer table is an essential reference.

Drug interactions

The Drug Interactions section lists clinically significant interactions, their mechanism (CYP inhibition/induction, pharmacodynamic, transporter-mediated), and management guidance (avoid, monitor, adjust dose). Not all possible interactions are listed — only those considered clinically relevant during development.

For comprehensive interaction checking, use clinical decision support tools such as:

• Drugs.com interaction checker
• NCBI drug interaction overview
• FDA CYP interaction table
• Drugs@FDA — individual label PDFs

Frequently asked questions