How Histamine Impacts Your Asthma

Histamine is a natural chemical produced by the body. Its main job is to send messages, some of which are helpful, like telling the brain to stay awake.

Histamine also acts as a relay messenger between different parts of the immune system and helps to keep foreign invaders at bay. But sometimes it does its job too well, leading to allergies.

How Histamine Works

Histamine tells your body's natural defense mechanisms how to react to something it perceives as foreign. With asthma and allergies, your body is over-reacting to something that is not particularly harmful but that has caused your immune system to react.

Immune cells called mast cells and white blood cells known as basophils release histamine when you are exposed to allergens. When histamine is released, the allergic response begins.

If the histamine release happens in your eyes, for example, your eyes may become itchy and watery. If it happens in your throat, your throat may be sore and scratchy. If the histamine release occurs in your lungs, you might have wheezing, chest tightness, shortness of breath and cough.

In asthma, histamine promotes bronchoconstriction—tightening of the muscles surrounding the airways in your lungs—and production of mucus.

Medications That Block Histamine

Antihistamine drugs are used in the treatment of the allergic symptoms caused by the release of histamine. Some popular anti-histamine medications include Zyrtec (cetirizine), Allegra (fexofenadine), Claritin (loratadine), and Benadryl (diphenhydramine).

Leukotriene modifying drugs, such as Singulair (montelukast), may also help by reducing the allergic response. The FDA has approved this type of drug for treating allergic rhinitis and asthma.

However, the FDA has warned about serious mood and behavior changes in people using Singulair (montelukast), so other treatments may be a better choice for some people, especially those with a history of mental illness.