Talk to your doctor and pharmacist about all of the medications you take. These include prescribed and OTC medicines and dietary supplements (vitamins, minerals, herbal products). Heed warnings on labels, too.

These can make a drug work less, increase the action of a drug, or cause side effects, even harmful ones. For example, unless told to by a doctor, do not take an antihistamine if you take medicine for high blood pressure or a sedative or tranquilizer.

Some medical conditions make taking certain drugs harmful. One example is taking a nasal decongestant if you have high blood pressure.

Alcohol should not be mixed with certain drugs. Grapefruit juice should not be taken with certain medicines for high blood pressure and high blood cholesterol.