I saw this article about over-the-counter allergy meds via Kevin, MD:
Over-the-counter hay fever medication works just as well as much more expensive prescription medication for seasonal allergies, according to a new study.
The research, published in the Archives of Otolaryngology -- Head & Neck Surgery, is based on a small sample and focuses exclusively on two specific drugs: a 240-milligram dose of pseudoephedrine hydrochloride (sold over the counter under the brand name Sudafed 24 Hour) and a 10-mg dose of montelukast sodium (prescription brand name Singulair). "When we compared them head-to-head, we found that for treatment of allergic rhinitis, these drugs at these doses were virtually identical," said Dr. Fuad Baroody, associate professor of surgery at the University of Chicago and the study's director. "This came as a genuine surprise."
OTC allergy drugs work great and are often more effective than perscription meds. For example, Benadryl is more effective than some perscription antihistamines. Sudafed is also very effective. The problem is that many of the OTC allergy meds have a lot of side effects. Benadryl can cause constipation, urinary retention, and confusion. Sudafed can cause hypertension and heart arrhythmias. Many of the OTC's would be considered too dangerous even for perscription status if they were being submitted to the FDA today.