The following substances commonly cause allergic reactions:

  • Grass and tree pollen
  • House dust mites or mould
  • Pets (tiny flakes of skin or hair)
  • Food such as nuts, some fruits, eggs and cow’s milk
  • Insect bites and stings
  • Medication
  • Latex
  • Household chemicals

Symptoms of an allergic reaction

Depending on the allergens you are sensitive to, the symptoms develop differently but quickly within a few minutes.

The most common symptoms are:

Respiratory problems such as:

  • Sneezing
  • A runny or blocked nose
  • Wheezing, chest tightness and coughing
  • Asthma

Skin problems such as:

  • Dry, red and cracked skin
  • Eczema
  • A red, itchy rash


  • Swollen lips, tongue, eyes or face
  • Red, itchy, watery eyes


Hay fever is a common allergic reaction. It is caused by grass pollen from May to July, tree pollen from February to June and weed pollen from June to September.

A food allergy is when the body’s immune system mistakenly recognises the proteins found in food as a danger. As a result, a number of antibodies are released that cause the symptoms of an allergic response.

Almost any food can cause an allergic reaction, especially milk, eggs, tree nuts, peanuts, fruits, fish and shellfish.