Doctors, nurses, and pharmacists can reduce the incidence of serious problems by keeping informed about potential drug interactions. Reference books and computer software programs can help. The risk of a drug interaction increases when drug prescribing isn't coordinated with drug dispensing and counseling. People under the care of several doctors are at highest risk because each doctor may not know all of the drugs being taken. The risk of drug interactions can be reduced by using one pharmacy to fill all prescriptions.
Drugs can interact in many ways.
A drug may duplicate or oppose another drug's effect or may alter the other drug's rate of absorption, metabolism, or excretion. Sometimes two drugs taken concurrently have similar effects, resulting in therapeutic duplication. A person may inadvertently take two drugs that have the same active ingredient. Aspirin may be an ingredient of cold remedies and of products intended for pain relief. More often, two similar but not identical drugs are taken concurrently.