Cromolyn is prescribed to prevent the symptoms of asthma and allergic rhinitis. This drug prevents the release of substances that cause these symptoms from mast cells and basophils in the blood. When cromolyn is taken directly, it prevents the frequency and severity of asthma attacks as well as the symptoms of allergic rhinitis. The inhaled form of Cromolyn can be used to prevent an asthma attack following breathing cold air, exercising or breathing substances such as pollutants or allergens. As soon as the condition of the body is stabilized with cromolyn, it may be possible to reduce the amount of other anti-asthma or anti-allergy drugs taken with the opinion of the attending physician. It is worth noting that cromolyn has no effect on the recovery or control of an asthma attack and may even aggravate the attack.