We appreciate the interest of Dr Dahl in our recent article in CHEST1 on the role of tiotropium for patients with asthma. Dr Dahl is concerned with the potential undesirable effects related to the use of tiotropium. In this sense, he is correct in asserting that the warnings come only from the use of tiotropium in patients with COPD. On the contrary, tiotropium appears to be safe and well tolerated in patients with asthma (one of the conclusions of our article). Therefore, it is questionable whether the Tiotropium Safety and Performance in Respimat (TIOSPIR) trial2 should be referenced in our article, because it was not conducted on patients with asthma. In any case, the results of our article regarding the safety of tiotropium in asthma were similar to those of the TIOSPIR study for COPD.