We evaluated the tolerance to NIM in patients with adverse reactions to NSAIDs, expressed by urticaria-angioedema, bronchial asthma or erythema polymorphous on 92 patients among which 32 atopics affected by asthma, rhinitis or contact dermatitis. Challenge test has been performed with increasing amounts of NIM per os every 2 hrs to a maximum of 100 mg/dose. The last dosage was repeated every 12 hrs for 4 times more. No reactions were observed in 86 patients (93.4%). Moreover we evaluated the efficacy of NIM in modulating pomphoid cutaneous reaction to histamine (HIS) and codeine (COD). Three subjects were prick tested with HIS and COD solutions at different concentrations (0.1 to 10 mg/ml), before and after a 5 days therapy with NIM at different dosages/kg/die. At NIM dosages of 3.7 and 2.7 mg/kg/die we observed a strong reduction of pomphoid activity of both HIS and COD. No clear effects were detected at 2.2 mg/kg/die dosage. We assume a dose-related in vivo inhibitory effect of NIM on cutaneous mast cells releasability or a direct anti-histaminic effect. We point out the possible therapeutic role of NIM in the treatment of allergic flogosis at steroid and cromon's side.