Allergy Fact Sheet: Types, Symptoms And Treatment

What is an allergy?

  • An allergy refers to an exaggerated reaction by the immune system in response to exposure to certain foreign substances like food, pollen, dust and household chemicals. 
  • The response is exaggerated because these foreign substances are normally seen by the body as harmless in non-allergic individuals and do not cause a response in them. 
  • In allergic individuals, the body recognizes the foreign substance, and the allergic part of the immune system generates a response.
  • Allergies are very common. They affect about one in five people at some point in their lives.
  • They are particularly common in children. Some allergies go away as a child gets older, although many are lifelong. Adults can develop allergies to things they weren't previously allergic to.
what are allergies 25 doctors

Common allergens

Substances that cause allergic reactions are called allergens. Common allergens include:

  • Grass and tree pollen – an allergy to these is known as hay fever (Allergic rhinitis)
  • Dust mites

  • Animal dander (tiny flakes of skin or hair)

  • Food – particularly nuts, fruit, shellfish, eggs and cow's milk

  • Insect bites and stings

  • Medication – including ibuprofen, aspirin, and certain antibiotics

  • Latex – used to make some gloves and condoms

  • Mould – these can release small particles into the air that you can breathe in

  • Household chemicals – including those in detergents and hair dyes

Most of these allergens are generally harmless to people who aren't allergic to them.

Symptoms of an allergic reaction

Allergic reactions usually happen quickly within a few minutes of exposure to an allergen. Although allergic reactions can be a nuisance and hamper your normal activities, most are mild. Very occasionally, a severe reaction called anaphylaxis can occur.

They can cause:

  • Sneezing
  • Runny or blocked nose

  • Red, itchy, watery eyes

  • Wheezing and coughing

  • A red, itchy rash

  • Worsening of asthma or eczema symptoms

  • Sneezing and an itchy, runny or blocked nose (allergic rhinitis)

  • Itchy, red, watering eyes (conjunctivitis)

  • Wheezing, chest tightness, shortness of breath and a cough

  • A raised, itchy, red rash (hives)

  • Swollen lips, tongue, eyes or face

  • Tummy pain, feeling sick, vomiting or diarrhoea

  • Dry, red and cracked skin

  • Worsening of asthma or eczema symptoms

Severe allergic reaction (anaphylaxis)

anaphylaxis anaphylactic shock allergy

In rare cases, an allergy can lead to a severe allergic reaction, called anaphylaxis or anaphylactic shock, which can be life-threatening. This affects the whole body and usually develops within minutes of exposure to an allergen.

Signs of anaphylaxis include any of the symptoms above, as well as:

  • Swelling of the throat and mouth

  • Difficulty breathing

  • Light-headedness

  • Confusion

  • Blue skin or lips

  • Collapsing and losing consciousness

Anaphylaxis is a medical emergency that requires immediate treatment.

How are allergies treated?

The best way to keep your symptoms under control is often to avoid the things you're allergic to.
For example, you may be able to help manage:

  • Food allergies by being careful about what you eat.

  • Animal allergies by keeping pets outside as much as possible and washing them regularly

  • Mould allergies by keeping your home dry and well-ventilated, and dealing with any damp and condensation.

  • Hay fever by staying indoors and avoiding grassy areas when the pollen count is high

  • Dust mite allergies by using allergy-proof duvets and pillows, and fitting wooden floors rather than carpets.

Allergy medications

Medications for mild allergies are available from pharmacies without a prescription, but always ask your pharmacist or GP for advice before starting any new medicine, as they're not suitable for everyone.
They can be taken as tablets, capsules, creams, liquids, eye drops or nasal sprays, depending on the part of your body affected by your allergy.
Treating severe allergic reactions (anaphylaxis)
If you're at risk of this, you'll be given special injectors containing a medicine called adrenaline to use in an emergency.
If you develop symptoms of anaphylaxis, such as difficulty breathing, you should inject yourself in the outer thigh before seeking emergency medical help.

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