What happens to your body when you have allergies
Common symptoms of an allergic reaction include:
- wheezing, chest tightness, shortness of breath and a cough
- tummy pain, feeling ill, vomiting or diarrhoea
- itchy, red, watering eyes (conjunctivitis)
- a raised, itchy, red rash (hives)
- swollen lips, tongue, eyes or face
- sneezing and an itchy, runny or blocked nose (allergic rhinitis)
- 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 own a skin allergy, or feel sick if you eat something you’re allergic to.
See your GP if you or your kid might own had an allergic reaction to something.
They can assist determine whether the symptoms are caused by an allergy or another condition.
Read more about diagnosing allergies.
Symptoms of an allergic reaction
Allergic reactions generally happen quickly within a few minutes of exposure to an allergen.
They can cause:
- a runny or blocked nose
- a red, itchy rash
- red, itchy, watery eyes
- wheezing and coughing
- worsening of asthma or eczema symptoms
Most allergic reactions are mild, but occasionally a severe reaction called anaphylaxis or anaphylactic shock can happen.
This is a medical emergency and needs urgent treatment.
Substances that cause allergic reactions are called allergens.
The more common allergens include:
- animal dander, tiny flakes of skin or hair
- mould – these can release little particles into the air that you can breathe in
- food – particularly nuts, fruit, shellfish, eggs and cows’ milk
- dust mites
- latex – used to make some gloves and condoms
- insect bites and stings
- medicines – including ibuprofen, aspirin and certain antibiotics
- grass and tree pollen – an allergy to these is known as hay fever (allergic rhinitis)
- household chemicals – including those in detergents and hair dyes
Most of these allergens are generally harmless to people who are not allergic to them.
How to manage an allergy
In many cases, the most effective way of managing an allergy is to avoid the allergen that causes the reaction whenever possible.
For example, if you own a food allergy, you should check a food’s ingredients list for allergens before eating it.
There are also several medicines available to help control symptoms of allergic reactions, including:
- decongestants – tablets, capsules, nasal sprays or liquids that can be used as a short-term treatment for a blocked nose
- lotions and creams, such as moisturising creams (emollients) – these can reduce skin redness and itchiness
- antihistamines – these can be taken when you notice the symptoms of a reaction, or before being exposed to an allergen, to stop a reaction occurring
- steroid medicines – sprays, drops, creams, inhalers and tablets that can assist reduce redness and swelling caused by an allergic reaction
For some people with extremely severe allergies, a treatment called immunotherapy may be recommended.
This involves being exposed to the allergen in a controlled way over a number of years so your body gets used to it and does not react to it so severely.
Getting assist for allergies
See a GP if you ponder you or your kid might own had an allergic reaction to something.
The symptoms of an allergic reaction can also be caused by other conditions.
A GP can assist determine whether it’s likely you own an allergy.
If they ponder you might own a mild allergy, they can offer advice and treatment to assist manage the condition.
If your allergy is particularly severe or it’s not clear what you’re allergic to, they may refer you to an allergy specialist for testing and advice about treatment.
Find out more about allergy testing
Severe allergic reaction (anaphylaxis)
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 something you’re allergic to.
Signs of anaphylaxis include any of the symptoms above, as well as:
Anaphylaxis is a medical emergency that requires immediate treatment.
Read more about anaphylaxis for information about what to do if it occurs.
Sheet final reviewed: 22 November 2018
Next review due: 22 November 2021
An allergy is a reaction the body has to a specific food or substance.
Allergies are extremely common. They’re thought to affect more than 1 in 4 people in the UK at some point in their lives.
They’re particularly common in children.
Some allergies go away as a kid gets older, although many are lifelong.
Adults can develop allergies to things they were not 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 happen, but these are uncommon.