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WHAT  IS  AN  ALLERGIC  REACTION? 

An allergy is a condition in which the body reacts with unusual sensitivity to a substance or substances, which is then known as an allergen.

 

• The immune system is the body's natural defence against a harmful substance. Antibodies are programmed to recognize these, sticking to them and acting as markers for specialized defensive cells to destroy them. 
• An allergic reaction occurs when the body reacts as if a harmless substance is, in fact, harmful. The severity of the reaction depends upon the number of markers. The more markers there are the more histamine is released from the cells. Histamine is a substance that causes an inflammatory response and produces allergy symptoms. 

On repeat exposure to an allergen, antibodies bind to it, causing the mast cell to burst and release histamine. It is the histamine that causes the allergic reaction.

 

Allergy facts

 

Allergies are increasingly common, with 25 per cent of children believed to have some sort of allergy. 

• The link between allergies and increased pollution has proved inconclusive. 
• Most children will outgrow allergies after puberty. 
• Someone who has inherited a tendency to allergies in general is referred to as 'atopic'. 
• Exposure of a three to six month old baby to a substance appears to heighten susceptibility, but only rarely will a child under one have a severe allergic reaction. 
• An allergy is different from a sensitivity or intolerance. In an allergy, the tiniest amount of a substance will cause a reaction. 

Most usual allergens

Severe allergic reactions can be triggered by:

• Nuts
• Eggs
• Seafoods
• Grains
• Milk
• Swap and bee sting
• Drugs, such as penicillin, and aspirin
• Rubber products, such as latex 

ANAPHYLACTIC SHOCK

 

Generally, allergic reactions produce symptoms that require only basic treatment. Sometimes, though, the symptoms can be life-threatening.

 

• In some people, the body becomes 'sensitized' to a particular allergen. The first time that the person encounters the allergen, the reaction may be mild, but, subsequent attacks are more serious as a greater amount of histamine is released. 
• The quick release of large quantities of histamine causes a life ­threatening condition called anaphylactic shock, or anaphylaxis. Emergency measures must be taken. 
• Those with a nut allergy are particularly prone to sensitization, although the phenomenon can occur with any allergen. 

A child who is at risk of anaphylactic shock should wear a medic alert bracelet. This provides important information that could help to save his life

 

Signs and symptoms

 

The effects will depend on the severity of the allergic reaction. Anaphylactic shock can develop within a few minutes of contact with the allergen, or after a couple of hours.

 

• The signs and symptoms of minor allergic reactions include redness and swelling around the site of the bite or sting, puffy eyes, rash, nausea, tummy ache, diarrhoea and, occasionally, joint pains. 
• The very first signs of anaphylactic shock can be mild, such as a runny nose and a rash. 
• The symptoms quickly worsen, with red blotchy skin, tightness of the throat and breathing difficulties (as the histamine causes the tissues of the throat to swell up). The lips, tongue and face swell, too, and some people experience vomiting and diarrhoea. There may be light-headedness and an irregular heartbeat.
• Children who also have asthma are at increased risk of a severe attack, because of their susceptibility to breathing difficulties. 

First-aid treatment

 

Call the emergency services immediately if you suspect that your child is going into anaphylactic shock. Give any information you have about the cause of the condition. 

If your child has an adrenaline (epinephrine) syringe for self-use (the hospital may have issued him with one if he has had anaphylactic shock before), help him to use it or give it yourself if you have been trained to do so. 

Placing your child in a sitting position may help to relieve breathing difficulty, but don't do so if breathing is hindered. If he becomes unconscious and is breathing, put him into the recovery position. 

Be prepared to give rescue breaths and chest compressions if necessary. 

NOTE: antihistamine tablets or syrup can be given, but not if your child is having trouble breathing, because of the danger of choking.

 

Medical treatment

 

Anaphylactic shock can be treated successfully so long as medical treatment starts without delay.

 

• Adrenaline (epinephrine) is given by intramuscular injection, or, in special cases, directly into a vein, and usually symptoms start to abate fairly quickly. Further adrenaline injections may be needed over the next 24 hours. 
• An antihistamine is given either by injection or by intravenous drip, to combat the build-up of histamine. 
• Hydrocortisone may be given after an attack to prevent long-term consequences, especially for asthmatics. 
• A blood sample may be taken to confirm that the condition was, in fact, anaphylactic shock. 

Preventing allergic reactions’

 

The only way to prevent anaphylactic shock is to avoid the allergen responsible. Treat any symptoms immediately.

 

• If  there is a family history of an allergy, mothers are advised to breast-feed exclusively for four to six months and to avoid the allergen during pregnancy and while breast-feeding. 
• A specific allergen cannot be identified other than by 'challenge testing' with it, and it would be unsafe to do this. Record any allergic reactions and avoid the allergens in the future. 
• Children who are thought to be at risk from anaphylactic shock are given adrenaline syringes that can be used as soon as the symptoms appear-EpiPen and Anapen are both used in Britain. You, your child (if he's old enough) and any carers should know how to use the syringe. 
• Buy your child a warning bracelet that states the nature of any allergy and the possibility of anaphylactic shock. 

If your child is thought to be have an allergy, patch testing may be carried out to try to identify the substance that is causing the reaction.

 

For  More  Information:  Please  consult  your  physician  on  your  next  visit.