A new public health advisory from the Food and Drug Administration cautions users of three asthma medications -- Advair Diskus, Serevent Diskus and Foradil Aerolizer -- that the drugs "may increase the chance of severe asthma episodes, and death when those episodes occur."

The FDA has asked the drugs' manufacturers to add new warnings to the products' labels. The medications belong to a class of drugs called long-acting beta 2-adrenergic agonists (LABA), which help relax muscles near the airways in the lungs.

LABAs shouldn't be a first-line asthma therapy and should be used "only if other medicines [including corticosteroids] do not control asthma," reminds the advisory. Virginia Taggart, health scientist administrator at the National Heart, Lung, and Blood Institute, said this advice is consistent with the institute's asthma guidelines, which recommend LABAs for persistent asthma only if other less aggressive treatments fail.

Because LABAs used alone don't control asthma as well as inhaled steroids (such as Flovent) or leukotriene receptor antagonists (such as Singulair), LABAs are only recommended for use "with another controller medication," such as an inhaled steroid or a leukotriene inhibitor, she said. Advair already contains a second component -- a corticosteroid -- that prevents the release of some substances that cause asthma symptoms.

The advisory underscores a key message for patients with asthma, that, no matter what medication you're taking, Dr. Taggart said, you need to monitor your asthma.