Allegra: Somewhere Over the Counter

By Dr. Paul Ehrlich
We now read that Allegra is the latest antihistamine to go from prescription to over the counter (OTC). It will soon join its “second-generation” non-sedating cousins Claritin and Zyrtec, both excellent antihistamines, on the pharmacy shelves. When it does, only two popular antihistamines, Zyxal and Clarinex, will require a doctor’s prescription.

The story of Allegra, also known as “fexofenidine” is very interesting. Almost fifteen years ago there was what seemed to be the ideal antihistamine – Seldane (terfenadine). My patients loved it because, among other things, it worked well without the occasional side effect of fatigue. A few patients claimed they had problems of cardiac irregularities and were asked to discontinue the Seldane.

Then the bottom dropped out of the market because of unexpected deaths do to an adverse cardiac event resulting from disruption of the “P450 system”—basically, irregular heartbeat. Further study showed that the problem stemmed from use of Seldane simultaneously with erythromycin or a certain topical steroid, whose name I can’t recall, for eczema. Seldane was removed from the market, although some people swore by it—one patient bought 3000 pills in Europe, where it was slow to be removed from the market, and took them for years. In the meantime a new antihistamine, Claritin, became the household name, and still is.

As for Allegra, several years later I remember talking to a friend of mine who, at the time, was with the National Institutes of Health. I asked him about the new medication, fexofenadine, which was the view as Seldane without the P450 problem. It certainly was non-sedating, and it was the only antihistamine approved for use by airline pilots, which became fodder for some great PR. Still, I will never forget what my friend said to me. “Paul, it is a poor substitute.” Almost fifteen years later, I believe he was correct.

Allegra is adequate for a small percentage of patients who have problems with the sedating effects of other antihistamines. Benadryl (diphenhydramine) still works well, but is very soporific (don’t drive, operate heavy machinery, or pay full price a movie because you won’t see it all). Claritin and Zyrtec seemed to be the best OTC preparations for allergy symptoms, but may knock you out, too. (In fact, when Zyrtec came on the market, a representative from the company that made it gave me one, and I had to cancel my appointments for the rest of the day.) Still, some people swear by Allegra.

Dr. Ehrlich has consulted for Schering-Plough, the makers of Claritin

{Note: for Dr. Ehrlich’s other thoughts on prescription antihistamines vs. non-prescription, go here.}

Update: Now that Allegra is sold OTC, Zyrtec has launched an ad campaign pointing out that Allegra should not be taken with fruit juice. Fruit juice inhibits the absorption of the active ingredient, making it less effective.