ABSTRACT
Asthma and allergic disorders are both becoming increasingly common,
and unlike most of the other disorders that have also increased in recent years, asthma predominantly affects children and young adults. Two key
themes emerge from epidemiological work on allergies and asthma: first,
the importance of early-life environmental conditions in the development
of allergic sensitization, and second, the role of allergic sensitization as a
risk factor for asthma. Once asthma has developed, some patients clearly
have episodes triggered by allergic exposure, while in other asthmatics
allergy appears to be less important. Targeting allergic sensitization should
therefore be a sensible tactic both for preventing the development of asthma and for managing some, but perhaps not all, patients with established
asthma. Since current forms of allergen avoidance have not proved very
successful in managing established asthma, there is considerable interest
in using specific allergen immunotherapy to treat asthma. But a decision
to use immunotherapy to treat asthma must take into account both the
potential benefits and the known risks of treatment, and has to be made on a case by case basis.
