How Histamine Affects Your Asthma

Histamine is a natural chemical produced by the body. It has many functions, including acting as a relay messenger between different parts of the immune system. Overactive histamine has been linked to allergies.

How histamine works

Histamine mediates your body’s natural defense mechanisms, protecting you from harmful substances. Asthma and allergy symptoms occur when your body overreacts to something that is not particularly harmful but has caused your immune system to react.

When you’re exposed to an allergen, immune cells called mast cells and white blood cells called basophils release histamine. An allergic reaction begins when histamine is released.

This reaction affects different parts of the body, leading to a range of symptoms:

  • your eyes may become itchy and watery
  • Your throat may be sore and itchy
  • wheezing, chest tightness, shortness of breath, or coughing

If you have asthma, histamine may promote bronchoconstriction (tightening of the muscles around the airways in the lungs) and mucus production.

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What happens to the body during an asthma attack?

Medications that block histamine

Antihistamines are used to treat allergic symptoms caused by histamine release. Some popular antihistamines include Zyrtec (cetirizine), Allegra (fexofenadine), Claritin (loratadine), and Benadryl (diphenhydramine).

Leukotriene-modifying drugs, such as Singulair (montelukast), may also help reduce allergic reactions. The FDA has approved these drugs for the treatment of refractory allergic rhinitis and asthma. Refractory conditions are those that do not improve with standard therapy—the therapy is not recommended as first-line treatment for allergic rhinitis or asthma.

Due to serious neuropsychiatric side effects in some patients using Singulair, a boxed warning has recently been added that your doctor may recommend that you avoid this treatment option if you have a history of mental illness.

It should also be noted that although histamine can cause bronchoconstriction, antihistamines are not the first-line treatment for asthma attacks. Rescue inhalers like salbutamol are often prescribed for patients to carry and use at the onset of acute asthma symptoms.