According to Merck Medical's online manuals Library, a histamine reaction is essentially an allergic reaction. Histamine is the main chemical responsible for allergic reactions. Allergic reactions can cause nasal problems, irritation of the eyes and rashes. Many histamine reactions are the result of exposing the immune system to substances that cause an exaggerated reaction. A histamine reaction can be activated through substances in the air, food and medications.
Histamine is a part of the body's natural defense system, according to the American Academy of Allergy, Asthma and Immunology. According to Merck, the human body is protected with certain antibodies, mast cells, proteins, white blood cells and histamine. When an allergen enters the body, the immune system produces immunoglobulin E, or IgE, a type of antibody. The antibody binds itself with the white blood cells and enters it. Once delivered to the mast cells, the IgE antibody causes the mast cells to release high levels of histamine.
According to MedlinePlus, the effect of histamine released into the body is a common allergy symptom. Symptoms include high respiratory reactions, rashes and asthmatic reactions. Upper respiratory reactions include sneezing, watery eyes, throat irritation, and nasal congestion. Rashes on the skin can appear in the form of hives or eczema, depending on the person's condition and medical history. Histamine also plays a vital role in allergy-induced asthma by causing inflammation of the airways, according to the Asthma and Allergy Foundation.
According to Merck, treatment includes the use of allergy medications and vaccines. The most common medication to control a histamine reaction is an antihistamine. An antihistamine prevents mast cells from producing histamine, relieving most allergy symptoms. Allergy shots are also used for people who have food allergies, airborne allergies or allergies to insect bites. Allergy shots are given by an allergist within a few years to numb the immune system due to an allergen.
A severe histamine reaction can lead someone to enter anaphylactic shock, according to MedlinePlus. During anaphylactic shock, histamine causes the entire body to react to the allergen and can lead to death if not treated properly. The most common causes of an anaphylactic shock is an allergy to some medication or food.The most common symptoms are shortness of breath, dizziness, nausea, vomiting and a weak pulse. Emergency medical attention is required.
A histamine reaction can be prevented by avoiding the triggers that lead to an allergic reaction. An allergist performs allergy tests to determine the substances that cause the body to produce histamine.