Medically Reviewed by Dr. K on 17 March 2021

What Is an Allergy?

It's what occurs as the immune system responds to a normally harmless substance. Pollen, mould, and animal dander, as well as some foods and substances that irritate the skin, are examples of causes, which doctors refer to as “allergens."

Allergies are a very normal occurrence.


What Happens During an Allergic Reaction?

It all starts as you inhale, swallow, or come into contact with a trigger on your skin.

Your body responds by producing a protein named IgE, which binds to the allergen. Histamine and other compounds are absorbed into the bloodstream as a result. This results in the symptoms you experience.

What Are the Symptoms?

The way you're exposed determines your symptoms: through the environment, the eyes, food, or an insect bite.

If you have a nasal allergy (one that is caused by something you inhale), you can have the following symptoms:

  • Itchy or watery eyes
  • Sneezing
  • Itchy and runny nose
  • Feeling tired or unwell

Rashes and hives are typical signs of a skin allergy (a rash with raised red patches).

Stomach cramps, vomiting, and diarrhoea are all symptoms of food allergies.

If you get stung by a bee, you'll experience swelling, redness, and discomfort where the sting occurred.

The signs and symptoms may be moderate to extreme. The rest of them disappear as soon as the exposure finishes.

Mild ones can go unnoticed for a long time. It's possible that you're just feeling “off."

Moderate effects will make you feel sick, making you feel you have a cold or the flu.

Allergic symptoms may be very serious.


Is It Anaphylaxis?

Anaphylaxis is the most serious allergic response. It has an effect on the whole body. Among the signs and symptoms are:

  • Hives and itching throughout your body
  • Wheezing or shortness of breath – difficulty breathing
  • Hoarseness or tightness in the throat and chest
  • Tingling in the hands, feet, lips, or scalp

Anaphylaxis is a life-threatening condition, so dial 999 immediately. If you have an epinephrine auto-injector (EpiPen), use it and repeat if the effects don't change within 5 to 15 minutes. And if the signs seem to disappear after you gave yourself the injections, you should seek medical treatment right away since a delayed reaction could still happen.


Referenced on 2.3.2021:

  1. Asthma and Allergy Foundation of America.
  2. National Institutes of Health.
  3. American Academy of Allergy Asthma and Immunology.
  4. Medline Plus: “Allergic Reactions."
  5. William Larry Haith, DO, FAAEM, Consulting Staff, Department of Emergency Medicine, Southern Maine Medical Center.

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