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What is Anaphylaxis?

Anaphylaxis is a sudden, severe and widespread allergic reaction which affects several parts of the body. Anaphylaxis is a medical emergency and requires immediate medical treatment. Causes or triggers for anaphylaxis are different from person to person, but are often everyday things such as nuts, insect stings and medications. The symptoms tend to worsen quickly, and include a itchy red rash, coughing or wheezing, difficulty breathing, and, eventually, collapse and loss of consciousness. For people at high risk, it may be useful to carry around an emergency kit, especially when traveling to areas where medical help is not readily available. If treated quickly and appropriately, most people recover well after an episode of anaphylaxis.


Anaphylaxis is an extreme allergic response. Allergies occur when the immune system overreacts to a normally harmless substance. These substances are called allergens or triggers. In anaphylaxis, the reaction involves the whole body, and causes swelling in different areas, including the airways. The trigger for these reactions are different. Around 1-2 percent of people will have an anaphylactic reaction during their lifetime. Anaphylactic reactions tend to be more common in children and teenagers, though adults can also have reactions when they are exposed to triggers.


The symptoms of anaphylaxis can come on, progress and become life-threatening very quickly. The early symptoms of anaphylaxis are an itchy, pink or red rash, often with coughing and a rapid heart beat. As the anaphylaxis progresses, the affected person may develop difficulty breathing, low blood pressure and dizziness, abdominal pain, or a sudden urge to open their bowel. As the anaphylaxis worsens, the symptoms become even more severe, and the person may collapse, become completely unable to breathe and lose consciousness.


The diagnosis is based on a person's medical history and examination. Treatment is not delayed in order to carry out further diagnostic tests, since an anaphylactic reaction can progress very quickly.


The trigger must be removed from the person having the reaction as quickly as possible. Lifting the legs above the head may be useful in case of dizziness due to low blood pressure. The emergency doctor will often use intravenous fluids and adrenaline to raise blood pressure. Steroids and antihistamines are given to stop the excessive immune response. Oxygen and inhalant medications are used to help if there is any difficulty breathing. In severe cases, a breathing tube may be necessary until the immune reaction settles.


Avoiding known triggers is an important part of avoiding anaphylaxis. Many people who have had an anaphylactic episode in response to common substances or medication choose to wear a piece of jewelry (often a bracelet) which has their allergy engraved on it, to direct medical staff in the case of emergencies. For some people, it is possible to undergo desensitization therapy, which means the body is slowly exposed to the trigger responsible for their anaphylaxis. This causes the immune system to slowly get used to the trigger, helping to reduce the severity of the allergic reaction in the future. People at high risk of severe reactions should also have an allergy action plan for their school or workplace, which includes education on the prevention of exposure and how to act in case of anaphylaxis. Emergency kits can also be prescribed in some cases.