Women with asthma who take birth control pills may have fewer problems than those who do not, according to a new study. But anyone with asthma who takes a common painkiller could make things worse.

Researchers from McMaster University found that during natural menstrual cycles, women on the pill had lower levels of nitric oxide in their breath. That is considered a sign of airway inflammation, according to a news release on the work.

The researchers said that oral contraceptives may have a potential role in the treatment of premenopausal women with asthma.

A separate study from the University of British Columbia found that acetaminophen, the active ingredient in Tylenol, may raise the risk of asthma.

Researchers reviewed 19 clinical studies that compared acetaminophen use to wheezing or asthma. They found that the risk of asthma was higher among adults who take acetaminophen. The results were the same for children and those who took acetaminophen when they were less than a year old.

The authors of the study said the two may be linked because acetaminophen doesn't inhibit an enzyme involved in the inflammatory response of asthma.