Claritin, a heavily advertised allergy drug, contributed one-third of the company's revenues last year.

Industry executives said they would pursue the fight over allergy drugs inside the Bush administration.

Sales of another big seller, the allergy drug Nasonex, are also being affected by competition.

Dr. Kessler said that the drug companies were trying "to play both sides" with the allergy drugs.

Pharmacies nationwide are stocked with Clarinex, the company's new allergy drug.

This is the first spring in which Claritin, the most popular allergy drug, is available without a prescription.

Some allergy drugs can also disrupt a good night's sleep.

Also, employers should make sure health plans cover prescription medications if people don't benefit from over-the-counter allergy drugs.

Talk to your doctor about a seasonal allergy drug that may be appropriate for your symptoms.

The approach worked in the case of Allegra, the allergy drug sold by Aventis.