Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at April 30, 2016

Anaphylaxis is a sudden and serious allergic reaction that occurs when a person comes into contact with a substance that he or she is allergic to. It is also known as anaphylactic shock.


Definition & Facts

When people with allergies come into contact with those substances to which they are allergic, the body releases a flood of chemicals that typically causes a localized reaction. In anaphylaxis, the reaction can occur throughout the body and cause a person to go into shock. Anaphylaxis is an emergency medical condition that needs to be treated promptly and can be potentially life-threatening if left untreated.

Symptoms & Complaints

Symptoms of anaphylaxis can occur quite soon after exposure to allergens, though sometimes they can be delayed by a half an hour or even longer after the initial exposure. Typical symptoms of anaphylaxis include:


The immune system is responsible for producing antibodies whose purpose is to attack harmful foreign substances such as bacteria and viruses before they do any damage to the body. Sometimes the immune system misinterprets foreign substances and initiates an allergic reaction. In sensitive individuals this process goes into overdrive when allergens are detected leading to a mild anaphylactic reaction.

The first exposure to an allergen that causes anaphylaxis is usually mild, but a second exposure could be much more severe. People who have known allergies or a history of asthma are more at risk for anaphylaxis. The anaphylaxis process begins when a person comes in contact with an allergic substance. Common allergens include:

Rarely, exercise can initiate anaphylaxis. Certain foods eaten before working out or working out in cold or warm weather can do this. Medications such as penicillin, naproxen, ibuprofen, or contrast dyes used in imaging tests can cause a patient to develop the same symptoms of anaphylaxis.

Diagnosis & Tests

Doctors treating a possible anaphylactic reaction will ask several questions about the patient's medical history and if they have any known allergies. Physicians will also recommend that patients who may not know what caused the anaphylaxis work with an allergist to determine what substances may have caused the symptoms.

Blood tests and skin allergy tests may be used to determine if a patient reacts to certain substances and to determine a correct course of action. For patients who may have food allergies, a detailed food diary may be kept to monitor for symptoms of an allergic reaction.

Doctors may also recommend an elimination diet where the patient will abstain from eating certain types of food for a period of time and then reintroduce them back into their diet to determine if they cause symptoms.

Other disorders with similar symptoms will be ruled out as possible causes. Panic attacks, heart problems, lung problems, skin reactions that are not allergic in nature, seizure issues, or mastocytosis all have symptoms that mimic anaphylaxis.

Treatment and Therapy

Anaphylaxis requires prompt treatment at an emergency medical facility. Emergency personnel may treat anaphylaxis with CPR if a person's heart or breathing stops. They may also administer a dosage of epinephrine, also known as adrenaline, to help slow the allergic response of the body.

Oxygen may also be given to compensate for shallow breathing and constricted airways and an intravenous antihistamine may also be given to help restricted airways open by reducing inflammation.

Most people who have a known allergy carry an autoinjector with them in case they may come in contact with allergens. Autoinjectors that administer epinephrine are called epipens; they deliver a small dosage of epinephrine when pressed against the patient's thigh. This allows the patient to slow down the anaphylaxis process and to seek treatment at the nearest emergency facility.

Long-term treatment for most cases of anaphylaxis is the same as preventing future occurrences. For patients who react to insect stings or bites, they may benefit from immunotherapy, which involves a series of of allergy shots that are designed to decrease the body's sensitivity and reaction to allergens. Long-term treatment may also include taking medications to reduce allergy reactions such as an antihistamine or prednisone.

Prevention & Prophylaxis

Preventing future occurrences of anaphylaxis depends on the patient communicating their known allergies with health care providers, keeping their auto-injector with them and avoiding substances that have caused past allergic reactions.

Those with latex allergies need to inform all physicians about their allergy so that non-latex gloves can be used during exams and future surgical procedures. The same practice should be followed with medications so that they will not be administered and lead to anaphylaxis.

Patients should know how to use their auto-injector correctly as well as inform the people closest them how to use it in case a severe reaction occurs. Food allergies should be made known so that future anaphylaxis reactions can be avoided.