Anaphylaxis is a rapid, immune-mediated (allergic), systemic reaction to allergens (like food, medication or insect stings) that the individual has previously been exposed to. Anaphylaxis is a medical emergency that requires immediate medical treatment, as well as follow-up care with an allergist or immunologist.
Symptoms of anaphylaxis can vary from mild to severe and may be potentially life threatening. The most dangerous symptoms are low blood pressure, breathing difficulties, shock and loss of consciousness, all of which can be fatal. The most severe type of anaphylaxis, known as anaphylactic shock, will usually result in death within minutes, if untreated. Anaphylactic shock is characterized by inflammation of the throat and a sudden drop in blood pressure.
Even trace amounts of the allergen can result in a life-threatening anaphylactic reaction. Anaphylaxis may occur after inhalation, ingestion, skin contact or injection of an allergen.

Related Terms

Allergy, allergic reaction, anaphylactoid reaction, anaphylatoxin, autoinjectable epinephrine, bee sting, bronchospasm, cardiovascular collapse, drug allergy, epinephrine, EpiPenĀ®, food allergy, hives, hymenoptera stings, hypotension, immunologic reaction, insect sting, insect venom, passive transfer, penicillin, pseudo-anaphylaxis, respiratory arrest, true anaphylaxis.

passive transfer

Anaphylactic sensitivity can be transferred to a non-sensitive individual by exposure to fluid that contains the antibodies. This is referred to as passive transfer of the allergy. For instance, there have been some reported fatalities, which have resulted from passive transfer involving organ transplants.

common triggers (allergens)

Exercise: Although rare, exercise may trigger anaphylaxis. The reaction does not (necessarily) occur after every exercise session. In some cases, eating certain types of foods before exercising may also trigger anaphylaxis. Foods that have triggered anaphylaxis in reported cases include wheat, cheese, seafood and celery.
Food: It is possible for any kind of food to trigger an allergic reaction. However, some of the most common foods that cause severe anaphylaxis include: peanuts, nuts from trees (like walnuts, cashews or Brazil nuts), shellfish, fish, milk and eggs. According to the American Academy of Allergy Asthma & Immunology (AAAAI), about 100 people in the United States die each year from food-related anaphylaxis.
Insect stings: Most people who are stung by insects like yellow jackets, honeybees, paper wasps, hornets or fire ants experience discomfort and minor swelling. However, individuals who are allergic to insect venom can potentially experience life-threatening reactions to a sting. According to the AAAAI, anaphylaxis occurs in 0.5 to 5% of the U.S. population as a result of insect stings. At least 40 Americans die each year from anaphylactic reactions to insect stings.
Latex: Some products made from natural latex (like gloves, balloons and condoms) contain allergens that can trigger anaphylactic reactions in allergic individuals. Anaphylactic reactions are the greatest threat when the latex comes into contact with moist areas of the body or internal surfaces during surgery because more of the allergen can rapidly enter the body. According to the AAAAI, about 220 cases of anaphylaxis and three deaths per year are attributed to latex allergies.
Medications: Essentially any medication can potentially cause an allergic reaction. Anaphylaxis most commonly occurs after exposure to antibiotics and anti-seizure medicines. In addition, medical therapies including, vaccines, blood, blood products, radio contrast dyes, pain medications, ACE inhibitors and other drugs may also trigger anaphylaxis.
Penicillin: The antibiotic known as penicillin is one of the most common drug allergies. According to the AAAAI, anaphylactic reactions to penicillin cause 400 deaths in the United States each year.
Other: In rare cases, anaphylaxis has been associated with exposure to seminal fluid, hormones and extreme temperatures. When an unknown substance causes an anaphylactic reaction, it is referred to as idiopathic anaphylaxis.