"When choosing an OTC medication, it is important to discuss your prescription medications with your pharmacist so he or she can check for potential interactions," says Karen A. DiStefano, RPh, a member of the Rhode Island Board of Pharmacy. "Filling all of your prescriptions at the same pharmacy will make it easy for your pharmacist to check if there are any medications to be avoided.

"Patients with high blood pressure, for instance, should avoid cold and flu products that contain the nasal decongestants pseudoephedrine or phenylephrine," warns DiStefano, who is also a CVS pharmacist, since both of these active ingredients can increase blood pressure. For those with high blood pressure, other treatment options are available, such as those marked HBP or BP, which use chlorpheniramine maleate as their active antihistamine ingredient. Such medications could, however, affect "other conditions that may need to be considered when choosing an OTC product," she says, including "thyroid disorders, asthma and diabetes."