Histamine is a protein released by the body in response to an allergen (a substance such as pollen or animal dander that triggers an allergic reaction because the body perceives it as dangerous). When histamines are released into the bloodstream, they cause symptoms typical of an allergic reaction, including itchy, swollen skin, eyes and lips and respiratory problems such as sneezing, wheezing, coughing, shortness of breath and runny nose.
When a potentially harmful subject is detected, a healthy immune system will release antibodies to seek out and destroy the intruder in order to protect the body from infection from viruses and bacteria. However, during an allergic reaction, this system responds to common substances like food, mold and dust.
Once antibodies have captured an allergen, histamines are released. In the process of gathering help from other antibodies to fight off the offending substance, histamines cause inflammation, mucous production, skin reactions and other symptoms of allergies.
Fish, cheese, fermented foods and alcoholic beverages like red wine contain histamines that cause allergy-like symptoms such as itching, sneezing, headaches and difficulty breathing. This type of reaction to histamine-rich foods is not an immune response and is different from a true food allergy. Eliminate the offending food or beverage from your diet to avoid symptoms.
Histamines dilate the blood vessels causing itching, flaking and reddening of the skin. Hives, which are pink, red, or flesh-colored welts, can rise up when histamine is released and cause swelling under the skin. They may appear all over the body. Hives are caused by allergic reactions, illnesses or sensitivities to environmental irritants such as chemicals, soaps, detergents, certain fabrics and certain types of plants.
The release of histamine can cause sinus inflammation and excessive mucous production, resulting in cough, congestion and nasal drainage. In moderate to severe cases, coughing, tightness in the chest and narrowing of the airways can make it difficult to breath.
Some allergic reactions are contained to one symptom and will not progress beyond the initial response to the release of histamines. But other allergic reactions can progress quickly and cause sometimes deadly symptoms.
An extreme overreaction by the immune system to an allergen can result in anaphylaxis, a potential deadly response that causes your blood pressure to drop and your airways to close in a matter of minutes. Allergies to specific foods, insect stings and certain medications such as sulfa-based antibiotics, are most likely to trigger anaphylaxis in susceptible individuals.
Mild allergic reactions and reactions to histamine-rich foods are treated with over-the-counter and prescription medications called antihistamines.
If you have trouble breathing, feel worse as time goes by, or have swelling in your face or extremities, call 911 and try to get emergency medical help immediately.