Cigarette smoking in asthma.

A survey was performed of smoking habits and respiratory symptoms of 106 asthmatic patients attending a hospital out-patient clinic. A quarter of the patients were currently smokers and a further quarter were ex-smokers. Less than a third of the smokers complained of symptoms of wheeze or dyspnoea after smoking. Asthmatic smokers had a much higher prevalence of chronic cough but their lung function appeared no lower than non-smokers. Ten asthmatic smokers were selected to contrast their acute bronchial response to smoking a currently marketed cigarette with that of ten asymptomatic smokers. Only four of ten asthmatic patients and two of ten asymptomatic smokers developed acute airway narrowing after smoking despite changes in venous blood nicotine levels which confirmed cigarette smoke inhalation. Many more asthmatic patients smoke than might be expected from the known instability of their airways. Our failure to show frequent and substantial airway reactivity to cigarette smoke in these patients suggests either that cigarette smoke may not be as acutely irritant as might be anticipated or that some asthmatic patients acquire tolerance to it. The effects of chronic cigarette consumption could be demonstrated even in this small sample which suggests that asthmatic patients should be advised to stop smoking, especially as many clinicians expect asthma and smoking to be a rare coincidence.