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Glossary · Tier 1

Active Ingredient

Also known as: active pharmaceutical ingredient, API, drug substance

Verified from FDA Drugs@FDA Glossary on 06-02-2026
Quick answer

An active ingredient is the part of a medication that produces the intended biological effect, as distinct from inactive components such as binders, fillers, or coatings. The term is central to how regulators identify, compare, and label drug products, including assessments of generic equivalence and labeling content. The official FDA definition follows below.

MedivaScan summary. The authoritative source quote follows below.

FDA Drugs@FDA Glossary definition

An active ingredient is any component that provides pharmacological activity or other direct effect in the diagnosis, cure, mitigation, treatment, or prevention of disease, or to affect the structure or any function of the body of man or animals.

U.S. Food and Drug AdministrationView on source ›Verbatim quote. Last verified 06-02-2026.
For information only. MedivaScan summarizes public FDA data and is not medical advice. Consult a healthcare professional before changing any medication. If you experience a serious reaction, contact your doctor or call 911.