Antihistamine use linked to extra pounds

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Antihistamine use linked to extra pounds

Wednesday, August 25, 2010

By Amy Norton, Reuters

 



A pharmacist helps a customer choose an over-the-counter antihistamine in a file

photo.

 

Photographed by:

Pierre Obendrauf, The Gazette

People who use prescription antihistamines to relieve allergy symptoms may be

more likely than non-users to carry excess pounds, a new study suggests,

although the significance of the connection is not yet clear.

In a study of 867 U.S. adults, researchers at Yale University in New Haven,

Connecticut, found that prescription antihistamine users were more likely to be

overweight or obese than non-users were.

Among the 268 antihistamine users, 45 percent were overweight, versus 30 percent

of the 599 study participants not on the medications.

The researchers stress, however, that the findings do not prove that

antihistamines are the cause of the extra pounds. This type of study, known as

an observational study, can only point to an association between two variables

-- in this case, antihistamine use and body weight -- and cannot prove

cause-and-effect.

It's possible that some other factor explains the link, according to lead

researcher Dr. ph Ratliff, a postdoctoral associate in Yale's department of

psychiatry.

" There have been studies that show allergies and asthma themselves are

associated with obesity, " he told Reuters Health in an email, " so these

conditions themselves may have an effect. "

Still, in a report in the journal Obesity, Ratliff and his colleagues say the

findings point to an important question for future studies to explore.

According to Ratliff, the researchers were interested in looking at the

relationship between antihistamines and weight because of what's known about

medications called atypical antipsychotics.

Those drugs -- such as olanzapine (Zyprexa) and risperidone (Risperdal) -- are

used to treat schizophrenia and other mental illnesses and carry the side effect

of weight gain. They also have antihistamine effects.

Histamine is a chemical produced in the body that is best known for its role in

promoting the inflammation associated with allergic responses; blocking

histamine is a good thing when it comes to relieving hay fever symptoms, for

instance.

But cells throughout the brain have receptors for histamine, and the chemical

appears to have a hand in a number of physiological functions -- with appetite

control and calorie burning being among them.

So in theory, Ratliff explained, antihistamines could contribute to overeating

and slower fat breakdown.

The current findings are based on 867 adults who took part in a government

health survey in 2005 and 2006. All participants had their weight and height

measured, as well as their blood sugar, cholesterol and levels of the

blood-sugar-regulating hormone insulin.

On average, antihistamine users had a higher body mass index (BMI) -- at about

31, which falls into the category of obesity. That compared with a BMI of about

28 among non-users, which correlates to being moderately overweight. BMI is a

standard measure of weight in relation to height used to gauge obesity.

When the researchers accounted for participants' age and sex, antihistamine use

was linked to a 55 percent increase in the odds of being overweight versus

non-use. The medications were not linked to higher odds of elevated blood sugar,

insulin or cholesterol, however.

More studies are needed to see whether antihistamines do in fact have an effect

on body weight.

The question is important, Ratliff and his colleagues note, as an estimated 50

million Americans have allergies, and anywhere from 35 percent to 50 percent of

them use antihistamines.

For now, Ratliff recommended that people with allergies talk with their doctors

about all the potential side effects of the different treatment options, and try

to find one that works best for them.

Other allergy treatments include corticosteroid nasal sprays and eye drops,

decongestants, cromolyn sodium nasal sprays and allergy shots. Non-drug tactics

to managing allergies include limiting exposure to symptom triggers -- such as

pollen, mould or pet dander -- and using salt-water nasal washes.

SOURCE: Obesity, online August 12, 2010.

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