Anaphylaxis Reactions

This is a big and important topic and is the main reason this site was founded – to provide relevant and potentially life saving information to those who are seriously allergic to insect venom.

Anaphylaxis is a really serious condition and can lead to death – and so any of the comments and claims on this website should be read in the context of being written by an informed patient rather than a medical expert.

An anaphylactic reaction is usually triggered by a limited number of allergic exposures.

These include injection, swallowing, inhaling or skin contact with an allergen by a severely allergic individual.

EHornetxamples of injected allergens are bee, hornet, wasp and yellow jacket stings; latex; certain vaccines which have been prepared on an egg medium; and allergen extracts used for diagnosis and treatment of allergic conditions.

Antibiotics, contrast dyes, and anaesthetics can also trigger a reaction by injection – literally the body has the offending substance injected into the system.

Typically, a severe reaction caused by a food allergy occurs after swallowing that particular food, even a small bite. Foods most commonly associated with anaphylaxis are peanuts, seafood, general nuts and, in children particularly, eggs and cow’s milk.

Skin contact with the food rarely causes anaphylaxis.

An anaphylactic reaction from an inhaled allergen is rarer. An increasingly recognizable example is when an allergic individual inhales particles from rubber gloves or other latex products. For some people, two or more factors may be needed to cause anaphylaxis.

Recently, it has been recognized that some persons have experienced an anaphylactic reaction if they eat a certain food, and then exercise. Neither the food alone nor exercise alone causes any problem for these individuals.

When exposed to a foreign substance, some people suffer reactions identical to anaphylaxis, but in which no allergy is involved. In this context allergy is defined as a reaction which is mediated by a specific IgE response from the body’s immune system.

These reactions are called anaphylactoid (meaning anaphylaxis-like) reactions. While the immune system must be “primed” by previous exposure to cause anaphylaxis, anaphylactoid reactions can occur with no previous exposure at all. An example of something that can bring on this kind of reaction is radiographic contrast material (the dye injected into arteries and veins to make them show up on an X-ray). Fortunately, health care providers don’t need to distinguish between anaphylactic and anaphylactoid reactions during an emergency because the treatment is the same.


In a severe allergic reaction, or anaphylaxis, after exposure to the triggering antigen, you may suddenly

  • feel a tingling or burning sensation on the skin particularly extremities like fingers
  • develop hives over large areas of the body
  • begin having breathing difficulties and experience swelling of the throat
  • experience a rapid and severe drop in blood pressure
  • find that thinking becomes muddled as the brain and other vital organs become oxygen-starved.
  • experience a sense of doom and disaster

People seem to have their own anaphylactic route map – so any one or more of these symptoms may occur in any order. Interestingly, once an order has been determined for any one individiual, that individual will often follow the same route on the next shock with very similar time intervals.

Hundreds of people die annually from anaphylactic shock across the world and it has no geographical boundaries or limits.

What the Body is Doing

In anaphylaxis, cells of the immune system release massive amounts of chemicals – particularly histamine. As a result, blood vessels dilate and begin to leak fluid into surrounding tissues, producing swelling. Several organs can be affected: The skin frequently shows symptoms first. Hives, itching, swelling, redness or a stinging or burning sensation may develop. The loss of fluid from blood vessels causes a drop in blood pressure and the individual may feel light-headed or even lose consciousness.

Anaphylaxis can cause obstruction of the nose, mouth and throat. Individuals may first notice hoarseness or a lump in the throat. If the swelling is very severe, it shuts off the air supply and the individual experiences severe respiratory distress. The airways in the lungs can constrict, causing chest tightness, shortness of breath and wheezing – the classic symptoms of asthma. The person may experience nausea, vomiting, cramping and diarrhea. The gastrointestinal tract often reacts, especially if the allergen is something that was swallowed. Women may experience pelvic cramps due to contractions of the uterus. It’s worth repeating that anaphylaxis is rare.

The vast majority of people with allergies will never have an anaphylactic reaction.

Many people experience allergy symptoms which are only a minor annoyance, broadly as described in the mild systemic reaction. However, a small number of highly allergic individuals are susceptible to a life-threatening allergic reaction known as anaphylaxis.

Anaphylaxis, the most serious type of allergic reaction, is extremely rare. Symptoms,  as detailed in this website usually appear rapidly – within seconds or minutes-after exposure to an insect sting. In a few cases, however, reactions have been delayed as much as 12 hours. Rapid diagnosis is important so that treatment, whether at hospital or on the way to hospital, can be effected.

WaspCurrently, the treatment of choice for anaphylaxis is an intramuscular injection of epinephrine, a hormone the body produces naturally in the adrenal glands. Epinephrine counteracts the symptoms of anaphylaxis by constricting the blood vessels and opening the airways. The down side is that its effects last only 10 to 20 minutes per injection, has some potentially serious side effects, and it must be administered correctly at or before the onset of symptoms to be effective.

Epinephrine, known to the layman as adrenaline, is most effective for treatment of anaphylaxis when injected into a muscle. Epinephrine works rapidly to make blood vessels contract, preventing them from leaking more fluid. It also relaxes airways, helping the individual breathe easier, relieves cramping in the gastrointestinal tract and stops itching and hives. Even if the individual responds to the epinephrine, it is vitally important to go to an emergency room immediately! Other treatments may be given such as oxygen, steriods, anti-histamines and medications to improve breathing. Intravenous fluids may be necessary to restore adequate blood pressure. Additional medications may be given to counteract the effects of histamine and to help prevent a delayed allergic reaction.

If the victim is stung, as they normally are, outside of a hospital, the importance of being able to easily administer adrenaline cannot be understated. Allergic individuals should always carry an auto-injector with them which enables the non-medical victim to easily self administer the life saving adrenaline. Many doctors recommend that two auto-injectors be carried due to the short term efficacy of adrenaline and the possiblity that the auto-injector may not be administered correctly.

Do not wait until you get to hospital but self-administer the adrenaline in anticipation of the reaction getting worse. An injection of adrenaline should deliver the same result and it is worth asking your prescribing doctor for you to try out the different auto-injectors out.  At the moment in the UK the three most commonly used injectors are Epipen, Jext and Emerade.

Victims will find that the adrenaline often wears off after 10 to 15 minutes and so the symptoms may well deteriorate. If this is the case then another dose of adAmbulancerenaline will normally cause no harm and once again can reduce the very real threat that anaphylaxis poses to the life of the victim.

It must be stressed that anaphylaxis is very life threatening and the most important thing is to get to hospital as quickly as possible.

Finally, anaphylaxis can be bi-phasic or delayed – it is possible that you can have a shock a few minutes after a sting, recover and then have another delayed reaction up to eight hours later. I would recommend that if you have had anaphylactic shock you should stay in the vicinity of an emergency room for at least four hours but ideally eight hours.

I speak from experience in that I had my first anaphylatic shock on a Thursday at around 10.30, then a further one at around 5.00 pm later that day. I had another anaphylactic shock a few weeks later and the second part of the shock proved to be far more severe than the earlier one. So do not think you have beaten the shock for a good eight hours after it starts!

Please visit the Anaphylaxis Treatment section of this website for information on how to cope with anaphylactic shock.

For more information on anaphylaxis in general and particularly insofar as food allergies are concerned then we recommend you visit the Anaphylaxis Campaign website.