Histamines are compounds of mast cells that which are released in response to allergy and inflammatory conditions. As you exercise, blood vessels widen, blood flow increases and neurochemicals like histamine are released. The neurochemicals send signals from nerves to muscles and to activate intestinal immune cells. Intestinal immune cells have a balanced system of anti-inflammatory and pro-inflammatory. During this activation of immune cells, the pro-inflammatory process can overtake the anti-inflammatory and trigger an allergic reaction. In healthy people, this response is normal and may go unnoticed, but in others it can cause more serious health issues.
Symptoms of Excessive Histamine Reaction
Symptoms of excessive histamine can develop immediately after beginning exercise and may last for up to 4 hours after exercise is stopped. They can happen at various times and intensity levels and be unpredictable. Symptoms include feeling warm, fatigue, itching, hives (urticaria), nausea, wheezing and colic. Histamine reactions can begin as early as age 3 and are more common in women than men. In rare cases, exercise induced anaphylaxis can result.
Causes
Histamine over-reactions are seldom due to a single event or factor. Over-reactions are most commonly caused by co-factors. These co-factors can include alcohol, eating foods that cause allergic reactions, humidity, smoking and medications. Common foods that contribute to elevated histamine are seafood, cheese, peanuts, tomatoes, wheat, celery and corn. Food preservatives, infections or viruses, and medications or over the counter products such as NSAIDS and aspirin may also contribute or act as co-factors.
Prevention
Prevention is the best way of reducing the intensity and duration of the histamine reaction. Restricting trigger foods, wearing loose clothing and slowly increasing intensity levels may help reduce the chance of excessive histamine levels. Medications and over the counter products such as antihistamines, leukotriene modulators and oral steroids can reduce the risk of a histamine over-reaction.
Testing and Treatment
Skin RAST (radioallergosorbent) testing for food or environmental allergies, baseline serum Tryptase level and exercise challenge test are all used to determine if you are at risk of exercise induced anaphylaxis. If you are diagnosed with exercise induced anaphylaxis, you may be advised to restrict physical activity, reduce intensity of exercise, wear a medical alert bracelet and carry an emergency epinephrine injectable medication.
