Asthma is a chronic disease that affects the airways. Asthma is characterized by inflammation and spasm of the airways. Allergic asthma is the most common form of asthma. Allergic asthma is triggered by inhaling allergens such as dust mites, pet dander, pollens, mold, etc. These allergens cause inflammation and swelling of the airways. This results in coughing, wheezing and chest tightness. The role of antihistamines in the therapy of asthma has been controversial from the beginning, over 30 years ago. It was only natural that after histamine was demonstrated to cause bronchospasm, and was closely related to the allergic phenomenon, the antihistamines should be expected to be effective in the therapy of asthma.