Anaphylaxis

Anaphylaxis is a particularly severe or extreme allergic reaction. It is very different from the wheezing of anasthma attackor the sneezing that accompanieshay feverbecause it affects the whole body, rather than just the part of the body, such as the nose or lungs, where allergen exposure has taken place. For this reason, anaphylaxis is sometimes also called a systemic allergic reaction.

While you may be able to ride out an ordinary allergic reaction, like a bout of hay fever, anaphylaxis is considered a medical emergency and medical attention must always be sought as soon as possible. People at risk of anaphylaxis should be prescribed adrenaline (also known as epinephrine), a pen-like device which they should carry around at all times. Adrenaline makes the blood vessels contract, which reduces swelling, and relaxes the smooth muscle in the lungs, so as to help the breathing.

As soon as an anaphylactic attack starts, the adrenaline should be used straight away by removing the top of the auto-injector and jabbing it firmly into the outer thigh. If the symptoms do not subside, then a second injection can be given 10 to 15 minutes later, although you should never exceed the maximum number of adrenaline shots specified by your doctor. If you know you have been exposed, such as a bee sting, it’s best to give yourself an adrenaline shot, even before the symptoms start unless you have been advised otherwise.

Once symptoms subside, you should be kept in the hospital (once medical help has arrived) for several hours because attacks can recur or be delayed in their onset.

If the main symptom of anaphylaxis is a swollen tongue or throat, be aware that this can cause suffocation. If the swelling is visible, and if the person is turning blue or has become unconscious, because of the lack of oxygen, then the airway should be kept open by whoever is accompanying the person. One way is to insert the handle of a spoon with smooth edges over the tongue and into the throat.

If the person loses consciousness, they should be laid down on their side but if they have difficulty breathing, a sitting position is better (unless they have also lost consciousness, in which case it is safer to have them lie down).

If you are travelling, think ahead about how you will call for medical help if you suffer an anaphylactic attack. Make sure you always have a phone to hand and know the number of the emergency services. It is also important to wear a MedicAlert bracelet or pendant in case you should be found, or arrive at the hospital, in an unconscious state due to anaphylaxis. In particular, this will stop medical staff wearing latex gloves and clothing if this is your allergy as further exposure could be fatal.

The symptoms of anaphylaxis are varied and not everyone having an anaphylactic attack will experience them all. Anaphylactic responses tend to escalate and can prove fatal in less than an hour. Roughly, in order of appearance, they include:

• Itching all over the body
• Flushing of the skin
• Widespread swelling under the skin
• Difficulty in speaking, swallowing or breathing
• Rapid pulse, palpitations
• Anxiety, disorientation and a feeling of impending disaster - this last symptom is very specific to anaphylaxis
• Abdominal pain, nausea, and diarrhoea
• Dizziness, fainting, and collapse due to a dramatic fall in blood pressure

The latter stages of anaphylaxis are clinically known as anaphylactic shock or just as ‘shock’. Death from anaphylaxis occurs from shock, swelling around the mouth and throat, which blocks breathing, or from a severe asthma attack.

As with milder forms of allergic reaction, anaphylaxis occurs because of an over-reaction by the immune system to exposure to allergens – specific proteins that are present in various substances including foods, latex rubber, and certain drugs. A non-allergic person would not respond to these allergens, which are normally harmless. Substances containing allergens that can cause anaphylaxis to include:

• bee or wasp stings, snake venom
• peanuts
• tree nuts such as walnuts, Brazil nuts, almonds, and cashew nuts
• eggs
• milk
• sesame seeds
• fish, shellfish
• latex rubber
• beta-blockers and some other drugs
• immunotherapy, skin prick tests
• radio-contrast media used in medical imaging
• exercise, especially strenuous exercise and where other triggers are involved, like cold or food allergens

Occasionally, anaphylaxis occurs for no obvious reason. However, exposure to the allergen causes the production of Immunoglobulin E (IgE) antibodies which, in turn, trigger the release of histamine, and other chemicals, from immune cells. It is these chemicals which act on blood vessels to cause swelling, itching and the other symptoms of anaphylaxis.

If you have ever had a bad allergic reaction in the past, you should be reviewed by an allergy specialist to see if you are at risk of anaphylaxis. Even a tingling of the lips on exposure to particular foodstuff can be significant, because a subsequent reaction to it may progress to full-blown anaphylaxis. Referral to an allergy specialist is particularly important if you have asthma because this seems to be a strong risk factor for anaphylaxis. You may be a candidate for immunotherapy if your trigger is something that is hard to avoid, like wasp stings.

If you are allergic to foods such as nuts, eggs or sesame seeds, be meticulous about reading labels on pre-packaged foods because these will state if a product contains traces of your trigger, even if it is not a major component of it. In summary, you should be extremely vigilant about avoiding anaphylaxis triggers while also making sure you are always prepared to treat an attack.