What causes new allergies

What causes new allergies

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:

  1. decongestants – tablets, capsules, nasal sprays or liquids that can be used as a short-term treatment for a blocked nose
  2. lotions and creams, such as moisturising creams (emollients) – these can reduce skin redness and itchiness
  3. 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
  4. 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.


Symptoms of an allergic reaction

Allergic reactions generally happen quickly within a few minutes of exposure to an allergen.

They can cause:

  1. a runny or blocked nose
  2. wheezing and coughing
  3. red, itchy, watery eyes
  4. sneezing
  5. a red, itchy rash
  6. 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.


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.

What causes new allergies

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


Main allergy symptoms

Common symptoms of an allergic reaction include:

  1. wheezing, chest tightness, shortness of breath and a cough
  2. a raised, itchy, red rash (hives)
  3. swollen lips, tongue, eyes or face
  4. sneezing and an itchy, runny or blocked nose (allergic rhinitis)
  5. itchy, red, watering eyes (conjunctivitis)
  6. tummy pain, feeling ill, vomiting or diarrhoea
  7. 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.

What causes new allergies

They can assist determine whether the symptoms are caused by an allergy or another condition.

Read more about diagnosing allergies.


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.

What causes new allergies

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.

What causes new allergies

They’re particularly common in children. Some allergies go away as a kid gets older, although many are lifelong.

What causes new allergies

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.


Common allergies

Substances that cause allergic reactions are called allergens.

What causes new allergies

The more common allergens include:

  1. food – particularly nuts, fruit, shellfish, eggs and cows’ milk
  2. insect bites and stings
  3. medicines – including ibuprofen, aspirin and certain antibiotics
  4. dust mites
  5. grass and tree pollen – an allergy to these is known as hay fever (allergic rhinitis)
  6. animal dander, tiny flakes of skin or hair
  7. latex – used to make some gloves and condoms
  8. mould – these can release little particles into the air that you can breathe in
  9. household chemicals – including those in detergents and hair dyes

Most of these allergens are generally harmless to people who are not allergic to them.


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