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Anaphylaxis: A Very Nasty Shock!!


For some people an allergic reaction causes a bit of an irritating rash that can easily be relieved with a cool compress and antihistamines. But for other people it can turn in to a life threatening reaction.

What is anaphylaxis?

Anaphylaxis is an extreme and severe allergic reaction. The whole body is affected, often within minutes of exposure to the substance which causes the allergic reaction (allergen) but sometimes after hours.

What can cause anaphylaxis?

Common causes include foods such as peanuts, tree nuts (e.g. almonds, walnuts, cashews, and Brazil nuts), sesame, fish, shellfish, dairy products and eggs.

Non-food causes include wasp or bee stings, natural latex (rubber), penicillin or any other drug or injection.

In some people, exercise can trigger a severe reaction – either on its own or in combination with other factors such as food or drugs (e.g. aspirin).

What are the symptoms of a severe allergic reaction?

  • generalised flushing of the skin
  • nettle rash (hives) anywhere on the body
  • sense of impending doom
  • swelling of throat and mouth
  • difficulty in swallowing or speaking
  • alterations in heart rate
  • severe asthma
  • abdominal pain, nausea and vomiting
  • sudden feeling of weakness (drop in blood pressure)
  • collapse and unconsciousness

A patient would not necessarily experience all of these symptoms.

Why does anaphylaxis occur?

Any allergic reaction, including the most extreme form, anaphylactic shock, occurs because the body’s immune system reacts inappropriately in response to the presence of a substance that it wrongly perceives as a threat.

An anaphylactic reaction is caused by the sudden release of chemical substances, including histamine, from cells in the blood and tissues where they are stored. The release is triggered by the reaction between the allergic antibody (IgE) and the substance (allergen) causing the anaphylactic reaction. This mechanism is so sensitive that minute quantities of the allergen can cause a reaction. The released chemicals act on blood vessels to cause the swelling in the mouth and anywhere on the skin. There is a fall in blood pressure and, in asthmatics; the effect is mainly on the lungs.

What is the treatment for a severe reaction?

Adrenaline auto-injectors are prescribed for those believed to be at risk. Adrenaline (also known as epinephrine) acts quickly to constrict blood vessels, relax smooth muscles in the lungs to improve breathing, stimulate the heartbeat and help to stop swelling around the face and lips.


About adrenaline injectors


The Anapen has a mechanism whereby, on pressing a firing button, a spring-activated plunger pushes the needle into the outer thigh muscle, delivering a single measured dose. Visit for more information, to watch a video demonstration and to register for expiry alerts.

Distributor: Allergy Therapeutics plc, Dominion Way, Worthing, West Sussex, BN14 8SA.

Tel: 01903 844 700.


The EpiPen has a spring-loaded concealed needle that delivers a single measured dose when the pen is jabbed against the muscle of the outer thigh.  Visit for more information, to watch a video demonstration and to register for expiry alerts.

Distributor: Meda Pharmaceuticals Ltd, Skyway House, Parsonage Road, Takeley, Bishop’s Stortford, CM22 6PU.

Tel 0845 460 0000.


Jext is the most recent single-use adrenaline auto-injector to be made available. Jext has a locking needle shield which engages after use, designed to protect against needle stick injury. Visit for more information, to watch a video demonstration and to register for expiry alerts.

Distributor: ALK-Abelló Ltd, 1 Manor Park, Manor Farm Road, Reading, Berkshire, RG2 0NA.

Tel: 0118 903 7940.

Adrenaline injectors – key messages

If you or your child carries adrenaline, there are key messages you must remember:

Have your adrenaline with you at all times – no exceptions.

Check the expiry date regularly. An out-of-date injector may offer some protection, but this will be limited.

Get a health professional to show you how to use your injector. If you haven’t already been shown how, go back to the doctor who prescribed it and ask for a demonstration. Ask the practice nurse at your local GP surgery or the school nurse. AllergyWise online can help.

Get hold of a “trainer” pen and practise regularly. Contact the distributors above for details on how to obtain one.

If you suspect a reaction is serious or becoming serious, use your injector immediately – any delay could be extremely serious.

Dial 999 or get someone else to do it. Immediately after your adrenaline has been administered you will need to get to hospital because the symptoms can return and you may need further treatment.

Remember that children who have been prescribed adrenaline injectors need to go on to the adult dose when they weigh 30kg. This is likely to be somewhere between 5-11 years old.

With Thanks to The Anaphylaxis Campaign for their information

For more information on Anaphylaxis training please visit

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