Created by the National Library of Medicine, this web-based search system provides the structure, nomenclature, molecular formula, CAS registry number, toxicity, and physical properties for chemical substances.
Drug Information Portal
Provided by the National Library of Medicine, this site gives quick access to comprehensive information on a large selection of drugs.
This Food and Drug Administration (FDA) database includes information on approved and tentatively approved prescription, over-the-counter, and discontinued drugs.
MedlinePlus: Drugs & Supplements
This excellent resource provides thorough, easily understood information on prescription drugs, over-the-counter drugs, and herbs and supplements.