Can asthma be prevented?

Yes, with medication: An asthma patient has episodes of bronchospasm (airways tighten up) plus swelling of the airways & increased mucus. Inhalers like albuterol relax & open up airways; inhalers like Flovent (steroid) prevent or decrease swelling & mucus. Preventive medicines like singulair (montelukast) can help. Avoid triggers such as pollen, smoke, etc... Many children outgrow their asthma, but may get an episode years later.

Not really: Asthma is a syndrome - a collection of symptoms that we treat as a single disease as we don't know why it occurs. Some things appear to reduce the risk of asthma (growing up with pets, growing up not in the city, not being a poor urban child), but none reduce the risk to zero and many are not avoidable easily.

Not always...: Asthma exacerbations can be caused by allergic triggers and avoidance of these triggers will decrease the exacerbations. However, it is not always possible to avoid all known triggers and some episodes have no obvious associated triggers. So, asthma is not always avoidable.