An allergy is a reaction the body has to a particular food or substance.
Allergies are very common. They’re thought to affect more than 1 in 4 people in the UK 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.
Having an allergy can be a nuisance and affect your everyday activities, but most allergic reactions are mild and can be largely kept under control. Severe reactions can occasionally occur, but these are uncommon.
Allergic reactions usually happen quickly within a few minutes of exposure to an allergen.
They can cause:
sneezing
a runny or blocked nose
red, itchy, watery eyes
wheezing and coughing
a red, itchy rash
worsening of asthma or eczema symptoms
Most allergic reactions are mild, but occasionally a severe reaction called anaphylaxis or anaphylactic shock can occur. This is a medical emergency and needs urgent treatment.
Read more about the symptoms of allergies.
Symptoms of an allergic reaction usually develop within a few minutes of being exposed to something you’re allergic to, although occasionally they can develop gradually over a few hours.
Although allergic reactions can be a nuisance and hamper your normal activities, most are mild. Very occasionally, a severe reaction called anaphylaxis can occur.
Common symptoms of an allergic reaction include:
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
The symptoms vary depending on what you’re allergic to and how you come into contact with it. For example, you may have a runny nose if exposed to pollen, develop a rash if you have a skin allergy, or feel sick if you eat something you’re allergic to.
See your pharmacist if you or your child might have had an allergic reaction to something. They can help determine whether the symptoms are caused by an allergy or another condition. Read more about diagnosing allergies.