Oral challenges to detect aspirin and sulfite sensitivity in asthma.

Oral challenge with aspirin, or potential cross-reacting substances, is an effective method for establishing the presence of these sensitivities in asthmatic subjects. However, in patients with concomitant active irritable airways, testing is inaccurate and potentially dangerous. Strategies for dealing with these problems and other details important in conducting oral challenges are outlined. Sulfite challenges are conducted in a different manner and there has not been cross-sensitivity established between sulfite sensitive and aspirin sensitive asthmatics. However, many of the same problems created by heightened airway activity interfere with the accuracy of sulfite challenges. A special obstacle in interpreting the results of sulfite challenges is the issue of specificity. Oral challenges with solutions of sulfite improve sensitivity of the challenge procedure. But only low dose sulfite solutions (50 mg/ml or less) and capsules of sulfite salts are specific provoking substances for sulfite sensitivity.