Recently, we have reported that a nebulized solution of sodium cromoglycate (SCG) (Intal), a well known antiallergic agent, has an acute bronchodilator effect in patients with aspirin-induced asthma (AIA). Amlexanox is an antiallergic agent, with a structure similar to that of SCG. Therefore, we investigated the acute bronchodilator effect of amlexanox administered orally to adult asthmatics, focusing on a comparison between AIA and non-AIA patients. Fifteen patients participated, 8 having AIA and 7 non-AIA. After performing spirometry during remission, they were administered either amlexanox or placebo using a randomized double-blind protocol. Spirometry was then performed at 30, 60, 90 min, 2 h, and 3 h after administration. The placebo used was lactose. In the AIA group, FEV1 was significantly improved after administration of amlexanox. However, FEV1 was significantly decreased after placebo administration. On the other hand, in the non-AIA group, FEV1 was not changed after administration of either of the drugs. From these results, we conclude that amlexanox has an acute bronchodilator effect only in AIA patients.