The Food and Drug Administration asked the makers of three popular asthma medications to add new warnings to their labels warning that the drugs could increase the risk of severe asthma attacks and even death.

The agency asked the manufacturers of Advair, Serevent and Foradil to strengthen the warning labels to reflect this risk.The FDA said that even though the drugs decrease the frequency of asthma attacks, they can make the attacks more severe when they occur.

The drugs are used for long-term control and prevention of asthma symptoms. Patients should use short-acting inhalers to relieve sudden wheezing, according to the FDA's public health advisory.

In July, an advisory panel to the FDA said the three asthma drugs were safe enough to stay on the market.

Asthma is a chronic lung disease that afflicts about 15 million Americans, nearly 5 million of them children. The disease can cause episodes of wheezing, coughing and breathing difficulty.