Risk factors for severe allergic reactions

Scientific studies demonstrate that in people with mild or moderate food allergy, severity of allergic reaction to food can be aggravated by factors such as physical exercise, alcohol, medications or infection.

Physical exercise

Exercise increases the absorption of food allergens in the gut and the release of histamine from mast cells.

During exercise, the body’s demand for oxygen, energy and removal of metabolic waste significantly increases. One of the ways the body adapts to meet these requirements is a change of blood distribution.

As a result, blood circulation in the abdominal area reduces, so more oxygen can be delivered to the working muscles. Over time, lack of oxygen may damage the gut walls leading to increased permeability of the gut (leaky gut) and increased absorption of nutrients. Exercising before or after consuming allergenic food will increase absorption of the allergenic protein.

Exercise, especially of high intensity or long duration, leads to damages of the skeletal muscles. The body responds to these damages by stimulating the immune system cells so they can begin the process of repair.

The immune response to the damage is coordinated by specific messengers that help the cells in the body to communicate the damage in the muscles. They are called cytokines and chemokines. These messengers also activate basophils (a type of white blood cell) and mast cells to release histamine, which plays a key role in the development of an allergic reaction.

Food-dependent exercise-induced anaphylaxis

Scientific studies have demonstrated the phenomenon of food-dependent exercise-induced anaphylaxis. This is a disorder in which anaphylaxis develops during exercise that is taking place a few hours after the consumption of a specific allergenic food.

This phenomenon is only caused by the combination of food and exercise. High intensity exercises, such as running, playing football, tennis, basketball and even brisk walking increase the risk for food-dependent exercise-induced anaphylaxis.

The specific allergenic foods associated with the phenomenon include shrimp, shellfish, chicken, nuts, eggs and vegetables.


Alcohol can also affect absorption of allergenic proteins and stimulate the immune system.

Studies have demonstrated that its higher consumption increases blood levels of Immunoglobulin E (IgE), the antibodies which initiate an allergic reaction. Their boosted level will increase severity of allergic reaction and probably accelerate its development.

Alcohol has been shown to relax tight junctions in gut epithelium; a single-cell lining that limits the passage of potentially harmful substances from gut to bloodstream. Once relaxed, the absorption of allergenic proteins will increase.


Medications for treatment of the following conditions have been shown to multiply the risk for food anaphylaxis:

  • high blood pressure (beta blockers, angiotensin receptor blockers and angiotensin‐converting enzyme inhibitors);
  • elevated blood lipids (statins);
  • digestive problems (acid neutralizing medication);
  • pain (nonsteroidal anti‐inflammatory drugs like ibuprofen)

These medications will increase the absorption of allergenic protein in the gut and histamine release.


Long-lasting emotional stress leads to persistent increased production of the stress hormones cortisol, adrenaline and noradrenaline.

Studies have shown that these hormones cause immune imbalance and increase the risk of allergic reactions to food.


During an infection, a person with food allergy may be at higher risk of of an allergic reaction, as the amount of allergen needed to cause a reaction maybe lowered. Many people with food allergy also have asthma,a condition which can worsen with infection like colds and flu.

This is because the infections increase inflammation in the lungs.

Further reading