NANCY OSTROM, MD: The causes of asthma are not entirely clear, but it does seem that there's generally a genetic predisposition. Once someone has a predisposition, the actual triggers of asthma are varied, but some of the common ones are cold air, exercise, infection, common viruses, irritants and allergies.
ANNOUNCER: Sometimes, avoiding the irritation is all that is necessary.
JAMES KEMP, MD: Asthma can be very easily managed by an environmental modification if the individual is only allergic to one or two substances where they can be eliminated or significantly minimized in the environment. I'll give you an example of that.
If the individual is allergic, let's say, to an animal that's indoors, taking that animal from the bedroom to the living room, or maybe, more ideally, to the kitchen or outdoors eliminates that stimulus for inflammation, and therefore inflammation will diminish and the asthma episodes should diminish.
ANNOUNCER: But often, avoiding asthma triggers is not possible. So in practice, asthma usually requires medical therapy.
NANCY OSTROM, MD: Anyone who has symptoms of asthma needs treatment. It's a matter of whether they need it intermittently or something of a more preventative nature.
ANNOUNCER: If it's to quell an attack, asthma medicine is called "reliever" medicine.