Carbon Dioxide Gas May Treat Nasal Allergies

Sept. 15, 2011 -- Shooting a quick blast of carbon dioxide gas into the nose may ease some allergy symptoms, and the relief appears to last for about four hours.

When carbon dioxide (CO2) is blown through the sinuses in a kind of pressurized gas rinse, it may relieve symptoms like itchy, watery eyes, sneezing, and a runny nose, according to a new study. CO2 is a colorless, odorless gas that is exhaled with each breath. It also puts the "fizz" into soft drinks and is frozen to make dry ice.

And CO2 appears to work pretty quickly for allergy relief, says study researcher Thomas B. Casale, MD, chief of allergy and immunology at Creighton University in Omaha, Neb. "In this study it was within 30 minutes, and in a previous study we did it was within 10 to 20 minutes. So for patients that are having significant symptoms, it could provide very rapid relief."

Side effects were generally short-lived, but included headaches, tearing, and nose pain.

Casale, who has tried the treatment, says it feels like the sharp burn of a soda burp.

"It's almost like if you're drinking a carbonated beverage and somebody makes you laugh and it goes up your nose, and you know how it stings for a bit? Some people experience that with the carbon dioxide," he tells WebMD. "That sensation goes away as soon as you turn the gas off."

The study is published in the Annals of Allergy, Asthma, & Immunology. It was sponsored by Capnia, a company that hopes to market a hand­held carbon dioxide device to treat allergies. Casale says he has no financial interest in the company.

Researchers aren't entirely sure how the treatment may work, but they have some theories.

One theory, Casale says, is that the gas probably helps to blow allergens out of the nasal passages, where they are causing irritation.

Rinsing the Nose With CO2

For the study, researchers recruited 348 adults who had been allergic to dust mites, cats, dogs, mold, or roaches for at least two years, as determined by a positive skin prick test and a need for medication to control their symptoms. They were asked to stop their normal medications before testing.

People in the study were randomly assigned to receive either carbon dioxide gas or a placebo. Those in the carbon dioxide group were further divided into groups who got either low or high doses of the gas for either 10 seconds or 30 seconds.

People in the treatment groups were asked to wear a nosepiece that was attached to a cylinder that was filled with compressed gas. A regulator controlled the flow of gas, so that study participants got either 5 milliliters or 10 milliliters of gas per second for either 10 seconds or 30 seconds in each nostril.