In addition to the 'Interactions' sections available in most drug monographs (see Drug Information & Drug Monographs on this page), the following speciality tools can help identify specific drug interactions.
The National Library of Medicine has established the Drug Information Portal as a convenient way to search for information from multiple sources on nearly 20,000 drugs. Individual databases searched and linked to are listed below, but you can enter your search once in the Drug Information Portal and all databases with results will be shown.
The Center for Drug Evaluation and Research (CDER) website at the Food and Drug Administration contains information on drug approvals, labeling, side effects, equivalency, and withdrawals. Specific resources are listed below.