Smoking and asthma: dangerous liaisons

Cigarette smoking and asthma interact to induce important adverse effects on clinical, prognostic and therapeutic outcomes. This review examines recent evidence on the harmful effects of smoking in asthma, possible underlying inflammatory mechanisms for this altered response, management options for these patients and potential future therapeutic directions. Active smokers, particularly females, are at risk of developing asthma. Prevalence rates for smoking in asthma are relatively close to those found in the general population. Smokers with asthma experience worse asthma control than nonsmokers with asthma. Mechanisms for the adverse effects of smoking in asthma include altered airway inflammation and corticosteroid insensitivity. Quitting smoking can improve symptoms and lung function, but the low rates of smoking cessation highlights the need for improved strategies for managing these patients. Clinical trials assessing new therapies for asthma need to enrol smokers to identify treatments that are effective in the asthma smoking phenotype.