The protective effect of NaS in analgetic-induced asthma (AIA) was investigated in patients with AIA. In none of the patients was the asthmatic reaction to acetylsalicylic acid (ASS) completely inhibited by the oral administration of NaS. In a single patient, an intolerance reaction occurred after oral ingestion of the substance. In several patients, induction of tolerance towards acetylsalicyclic acid was facilitated after prior ingestion of NaS.