During an asthma attack a person comes in contact with an allergen or an irritant. This causes: inflammation (swelling) of the lining of the airways; tightening and constriction (tightening) of the muscles in the airways; and increase in mucus production. One, two, or all three of these actions can cause an obstruction in the airways making it very difficult to breathe. Giving the victim a feeling much like a fish out of water.