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What is allergy?

"Allergy" refers to the excessive reaction of the immune system when the body comes into contact with some generally harmless substances in the environment. These substances are known as "allergens". Some common allergens include dust mite, animal hair, pollen, grass, mold, insect stings, food and drugs.

The severity of allergic reactions varies from person to person, depending on the sensitivity of the body to the allergens. Some mild to moderate symptoms include itching, skin redness, urticaria (or hives), swelling, eczema flare-up, runny nose, etc. Severe allergic reactions (anaphylaxis) can lead to asthma attacks, wheezing, difficulty breathing, low blood pressure, dizziness, fainting or loss of consciousness, and even death.

People who have confirmed to be allergic to specific substances should avoid or minimise exposure to these allergens, so as to reduce the risk or frequency of allergic reactions.

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What is anaphylaxis?

Anaphylaxis is an acute, severe and fatal allergic reaction, which usually occur rapidly within seconds to hours after exposure to allergens. The symptoms are relatively severe, and for most of the time, more than one body system or organ are involved.

The major causes of anaphylaxis in adults are drug allergy or insect stings, while food-induced anaphylaxis is more common in children. In western countries such as Europe and Australia, food-induced anaphylaxis is mainly caused by peanuts or tree nuts. On the other hand, seafood is the most common trigger of food-induced anaphylaxis in Asian countries. Peanuts, eggs and milk are also common causes of anaphylaxis in Hong Kong.

Adrenaline autoinjector, such as Jext ® or EpiPen ®, are used as the first-line treatment of anaphylaxis. It contains a single fixed dose of adrenaline (epinephrine), with an automatic design allowing people who are not trained with syringe injection technique to easily and timely use it for emergency treatment.

More relevant information:

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