Call 999 immediately if someone may be having a serious allergic reaction.

This can include sudden swelling of the lips, mouth, throat or tongue, struggling to breathe, a tight throat, fainting, severe drowsiness, confusion, or a child becoming limp, floppy or not responding normally.

An allergy is where your body reacts to something that is normally harmless, such as pollen, dust, animal fur, certain foods, insect stings or some medicines.

Allergies are very common and can affect people of any age. They are particularly common in children. Some allergies go away as a child gets older, although many are lifelong.

Adults can also develop allergies to things they were not previously allergic to.

Having an allergy can be a nuisance and may affect everyday activities. Most allergic reactions are mild and can usually be kept under control, but serious reactions can sometimes happen.

NHS 111 Wales allergy information

Use NHS 111 Wales for trusted information about allergies, including symptoms, diagnosis, treatment and how to manage allergies safely.

Read the NHS 111 Wales allergy guide
Common causes of allergies

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

  • tree and grass pollen, also known as hay fever
  • house dust mites
  • foods, such as peanuts, milk and eggs
  • animal fur, particularly from pets such as cats and dogs
  • insect stings, such as bee and wasp stings
  • certain medicines
Symptoms of an allergic reaction

Symptoms of an allergic reaction can include:

  • a runny nose or sneezing
  • pain or tenderness around the cheeks, eyes or forehead
  • coughing, wheezing or breathlessness
  • itchy skin or a raised rash, also known as hives
  • diarrhoea
  • feeling sick or being sick
  • swollen eyes, lips, mouth or throat
When to contact your GP practice

Contact your GP practice if you think you or your child may have an allergy.

A GP may arrange allergy tests or refer you to a specialist allergy clinic. Tests may include a skin prick or patch test, blood tests, or a special diet where you avoid or reduce a food you may be allergic to, to see if symptoms improve.

Treatment and managing allergies

Treatment for allergies may include:

  • trying to avoid the thing you are allergic to whenever possible
  • medicines for mild allergic reactions, such as antihistamines, steroid tablets or steroid creams
  • emergency medicines called adrenaline auto-injectors, such as an EpiPen, for severe allergic reactions
  • desensitisation, also called immunotherapy, for severe allergic reactions. This should only be done by a medical professional.

Your specialist may give you an allergy management plan that explains how to manage your allergy.