Anaphylaxis

What is anaphylaxis?

Anaphylaxis or anaphylactic shock is a rare but serious condition, it is the end result of a severe allergic reaction. The reaction affects the whole body, causing a sudden drop in blood pressure and narrowing of the airways.

What causes anaphylaxis?

Anaphylaxis is caused by an extreme sensitivity to an allergen. The most common allergens which cause anaphylaxis are peanuts, tree nuts, bee/wasp stings or a drug, such as the antibiotic penicillin. For more information on food allergies click here.

It is unknown why some people get anaphylaxis and others don't, however, it usually happens to people who are known to have allergies.

How do I know if I'm at risk of anaphylaxis?

If you have previously suffered from a bad allergic reaction, then a future reaction may also be severe. If you ever experience any allergy symptoms (especially after eating nuts), no matter how mild, then this should be regarded as a possible warning sign of a more severe allergic reaction and you should seek your doctors advice. Allergic reactions are unpredictable and can vary in severity from one time to the next.

What are the symptoms of anaphylaxis?

The symptoms of anaphylaxis normally begin within minutes of exposure or contact to the allergen and can be quite rapid, though in some situations this process can take hours. Symptoms of anaphylaxis could include any of the following:

• Swelling and itching in the mouth and throat
• A rash, anywhere on the body and the skin may appear flushed.
• Difficulty in swallowing or speaking.
• Difficulty breathing
• Abdominal cramps
• Nausea and vomiting.
• Feeling of 'impending doom'.
• A drop in blood pressure, which makes the person feel weak
• Collapse and unconsciousness.

You may not necessarily experience all of the symptoms above and some people may only ever have mild symptoms, for example they may just notice a tingling or itching in the mouth. This can be treated with oral antihistamines. However, you should still seek your doctors advice because next time the reaction could be more severe.

Can anaphylaxis be diagnosed?

There are tests available to diagnose what specific allergens you are allergic to but as yet there is no perfect way of measuring an individual's potential for a severe allergic reaction. For more information on allergy tests read the section "How are allergies diagnosed?" on the allergies page.

What is the treatment for anaphylaxis?

The best treatment for anaphylaxis is avoiding the allergen to which you are allergic, especially if you have had a previous serious reaction. Please read the individual subjects on food allergies and insect bites for more tips on avoiding specific allergens.

It is important that if a person is suffering with anaphylaxis that they get immediate treatment with adrenaline (also named epinephrine) the minute a serious reaction is suspected. The adrenaline injection will raise the blood pressure, stimulate the heartbeat, relieve breathing difficulties and reduce swelling. In order for the treatment to be effective it must be administered very quickly. If you have had a previous serious reaction or your doctor suspects you are at risk of one, then you should be given a pre-loaded adrenaline injection to carry. You must ensure that you always have the adrenaline kit with you and make sure you are comfortable using the one that has been prescribed to you. If you are unsure speak to your doctor for advice or ask for a different kind.

Adrenaline treatments you could be given may include the following:

• Medihaler-Epi - if the symptoms include swelling of the mouth a treatment called a Medihaler-Epi should be used. A Medihaler-Epi is an aerosol containing adrenaline, the requirement is usually 4 puffs sprayed into the mouth. This type of treatment is not suitable for widespread allergic reactions.
• Epipens - the treatment of severe allergic reactions to foods has been revolutionised by the introduction of the Epipen auto-injector. This device has a spring-activated needle and is designed to deliver a single 0.3mg dose of adrenaline into your muscle when the pen is pushed into your skin.
• Min-i-jets - the Min-i-jet works in the same way as the Epipen but consists of a 1ml disposable syringe and needle. The dose will need to be measured accurately, as a full syringe will deliver 1mg of adrenaline.

The majority of food allergy sufferers prefer the use of the Epipen due to the ease and the simplicity. There is no visible needle and the device has a shelf-life of 2 years compared to 9 months for the Mini-i-jet. In some cases a single dose of the Epipen may not prove enough to treat severe reactions, you should always carry two Epipens as a safety measure. If you are at risk from severe allergic reactions then you must carry medications around at all times.

If you have suffered this kind of severe allergic reaction you should still go to a hospital for observation, or call an ambulance.

Your doctor should also give you an emergency card or bracelet, which you should always carry to alert others to your allergy. You should also inform those around you at work and home of your allergy. Show them where you keep your medicine and how to use it in case of an emergency. Make sure your medicine is always in easy access and that the expiry date has not passed.

If you believe you or someone else is having this severe reaction you should first try and administer adrenaline. Don't kid yourself of the symptoms, if you think you are beginning to show the signs of a severe reaction, reach for the adrenaline injection. If there is none available then call an ambulance or if closer get to a hospital or GP's clinic as soon as you can.