Count yourself lucky if you're NOT one of the estimated 50 million Americans who have allergies of some sort. Seasonal allergies send many people to the neighborhood pharmacy for relief in the form of an over-the-counter medication.
The most common OTC medicine allergy sufferers seek is an antihistamine, which blocks the release of histamine that is triggered by exposure to an allergen (i.e. pollen, animal hair) and makes you sneeze, break out in hives, get watery eyes, etc. First-generation antihistamines include brompheniramine (sold under the brand Dimetane) and chlorpheniramine (Chlor-Trimeton). Second-generation antihistamines include fexofenadine (Allegra) and loratadine (Claritin).
While second-generation antihistamines tend to cause less drowsiness than the first generation, experts say there really isn't much difference between them, according to Public Citizen's Health Research Group.
Whichever antihistamine you choose, be careful not to take too much, because all antihistamines can affect a nervous system transmitter called acetylcholine, which can result in slow digestion, high blood pressure, constipation, short-term memory loss and other bad side effects, according to Public Citizen.
Public Citizen recommends avoiding desloratadine, sold by Merck under the brand name Clarinex, because it isn't much of an improvement over loratadine (Claritin) but allows Merck to profit off weak U.S. patent laws, now that loratadine's patent has expired and is available generically.
Everyone should consult a doctor before taking OTC antihistamines. Many people think OTC medicine has less risk than prescription drugs, but misusing or overdosing on OTC drugs can be just as harmful, especially for older adults, Public Citizen says.
Public Citizen: Benefits and Risks of Popular Allergy Medications (subscription required)