Ask Dr. H: Antihistamines tied to obesity

Question:

I recently heard about a study that says antihistamines like Zyrtec and Benadryl can cause weight gain. I have allergies all year long and wonder if the 15 pounds I've gained over the last year may be due to that. What do you think?

Answer: For years, there have been reported associations between antihistamine use and the incidence of obesity. Most recently, an observational study published in the August 2010 issue of the journal Obesity found that of the roughly 900 folks studied, those taking antihistamines were more likely to be overweight or obese than those not taking antihistamines.

We do know that one of the older antihistamines, Periactin (cyproheptadine), is an appetite stimulant and has been used as such. We also have seen that for a small percentage of people, antihistamines can increase appetite. At the same time, we also see many folks who take antihistamines - especially the newer ones like Claritin, Allegra, and Zyrtec - with no reported weight gain. Perhaps the sedating effects of certain antihistamines may keep some in the house, with a less active lifestyle and more contact time with their kitchen as contributing factors to their weight gain. Another possible explanation for the antihistamine/obesity association may be that certain obese folks may have more issues with allergies and therefore are more likely to be taking an antihistamine.

For those who have allergies all year long, allergy desensitization shots may be a helpful long-term strategy. Intranasal steroid and antihistamine sprays as well as antihistamine eye drops may be other options for some. In the end, one has to balance the huge benefit of symptomatic relief from allergies against a small potential risk of weight gain.

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Q:

Several years ago, I was diagnosed with "BOOP" - Bronchiolitis Obliterans Organizing Pneumonia. I was placed on a prednisone taper over 10 months. Two months later, it started all over again and I needed another 10-month prednisone taper. My initial symptoms were loss of weight and shortness of breath. My doctor says they don't know what causes BOOP. Can tell me more about my illness?

A: When my readers think of pneumonia, they probably think of a bacterial infection that's treated with an antibiotic. But the term "pneumonia" is a broad term that refers to inflammation of the lung tissue which may be from a bacterial, viral, fungal or, in the case of BOOP, some known or unknown cause. BOOP on chest X-ray usually shows a patchy pneumonia process involving both lungs. The typical person with BOOP will have a gradual onset of dry cough, fever, malaise, and shortness of breath.

Multiple courses of antibiotics are usually tried without any improvement in how the patient feels or in the chest X-ray appearance.

To know for sure that someone has BOOP, an open lung biopsy is necessary to get a sample of lung tissue.

The treatment of choice for BOOP is a slow steroid taper over many months. In folks like you treated for about a year, one-third will relapse. One or two more rounds of steroids will usually treat BOOP successfully.

While BOOP may be caused by certain medications, toxic fumes, radiation therapy to the chest, or independently in folks with rheumatoid arthritis or any of the connective tissue disorders (e.g., lupus), perhaps 80 percent of folks develop BOOP without a known cause. Fortunately, BOOP is rather rare.