Primary prevention of atopic asthma.

Current recommendations given for primary prevention of allergic asthma often include advice on how to reduce exposure to inhalant allergens early in life. There is little support for such advice, however. On the contrary, recent studies indicate that extensive allergen exposure may actually reduce the likelihood of developing allergic asthma. However, recent studies indicate possible future venues for primary allergy prevention through immune modulation. This may possibly be achieved by stimulating the maturation of the immune system early in life by altering the microbial gut flora or by recently developed immunomodulatory Th2 antagonists. In the meantime, the avoidance of exposure to tobacco smoke remains the only recommendation that is reasonably well documented by evidence-based medicine, while allergen avoidance in primary prevention is not.