We have tried an antihistamine for this and it has worked great. However, my fiance is uncomfortable with him taking medication every time he visits us. Are there allergy injections he can take? What would you suggest?

This is a common and very difficult problem that you are facing. Cats are highly allergenic, and if your fiance's son has asthma and is allergic to your cat, then exposure to the animal can lead to asthma flares that an antihistamine can't protect him from. If his visits are short and infrequent, he may have a flare for a few days after each visit. However, if he visits regularly (i.e., weekly) his asthma will probably begin to get steadily worse, and the flares more severe. There are allergy shots that can help him to become less allergic, but it takes about 7 months of weekly injections to safely get up to an effective dose, and then with continued shots he'll gradually lose the allergy over the next 2-3 years. In the meantime, there is an over-the-counter medication called Nasalcrom, which if used about 20 minutes before exposure, will protect the nose for a few hours from allergen (i.e., cat) exposure. A similar preparation for the lungs is available by prescription. It's not perfect, but it may help. Unfortunately, there's no instant fix for this problem, and asthma attacks can be life threatening. The best way for an allergic person to have a pet is to get onto an effective dose of allergy shots before getting the pet. Of course, you didn't have that option with your step-son-to-be. I know it doesn't seem fair, and I don't envy your position, but depending on your wedding date and living arrangements, you may have a difficult decision to make.

Good luck, Dr. White

-- Dr. Martha Vetter White, MD, is cofounder and director of research at the Institute for Asthma and Allergy in the Washington, DC metropolitan area, one of the nation's most active clinical research centers devoted to allergy, asthma, and sinusitis.

Last updated July 30, 2009