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Allergies

An allergy is a reaction by the body to a particular food, chemical, or specific trigger. These triggers are termed ‘allergens’. Allergens are harmless to the majority of people, but can cause reactions. These reactions are sometimes very severe in specific individuals.

There are multiple different types of allergy. The most common are:

  • Grass and tree pollen (known as ‘hayfever’)
  • Animal allergies (such as from cats or dogs etc)
  • Dust mite allergy
  • Certain chemical allergies
  • Reaction to insect bites and stings
  • Latex allergy
  • Specific food allergies (common ones being nuts, shellfish, eggs or cow’s milk)
  • Reaction to medication (like penicillin)

Many allergies exist in childhood and go away with age. Others may persist throughout adulthood. Some people even develop new allergies as an adult.

For mild allergies, symptoms include:

  • Sneezing, runny or blocked nose
  • Itchy or watering eyes
  • Itchy, raised red rash (called ‘hives’)
  • Coughing, chest-tightness or worsening of asthma symptoms
  • Abdominal pain, diarrhoea or vomiting

Allergy symptoms vary depending on the type of allergen and the way you’re exposed to it. For example, a pollen or dust allergy is more likely to cause respiratory and nasal symptoms like a cough or sneezing, while a food allergy is more likely to cause diarrhoea or a rash.

In some cases, allergic reactions can be very severe. Symptoms include:

  • Swelling of the lips, mouth, tongue or throat
  • Wheezing
  • Difficulty breathing
  • Red, raised, itchy rash
  • If untreated, collapse and loss of consciousness

Severe allergic reactions of this type are called anaphylaxis.

Anaphylaxis is a severe reaction to an allergen. Anaphylaxis develops and progresses quickly (within a few minutes) and can be fatal if not treated immediately. If severe symptoms – like those listed above – occur, get emergency treatment.

What to do if someone has anaphylaxis:

  • Use the person’s adrenaline ‘pen’ if you can do it correctly
  • Call 999 for an ambulance immediately, even if symptoms seem to improve. Tell them you think the person has anaphylaxis
  • Remove any trigger that might be around or touching the skin
  • Lie the person down flat – unless they're unconscious, pregnant or having breathing difficulties
  • If available, give another injection after 5 to 15 minutes if the symptoms do not improve

Avoidance of the allergen which triggers symptoms is the best way to manage allergies.

But for some types of allergy – like grass pollen – this is hard to do. A pharmacist would be able to help with allergy treatments in this case, such as:

  • Antihistamines - Medications containing the ingredient cetirizine or loratadine are available over the counter and generally do not cause sleepiness
  • Decongestant nasal spray - These can be used for acute relief of a blocked or stuffy nose, but should not be used for longer than 7 days
  • Steroid nasal sprays - Mild steroid nasal sprays are available without prescription and can reduce inflammation in the nose caused by allergies
  • Eye drops with antihistamine - for relief of itchy, watery eyes

If symptoms are still present despite the above treatment then a GP can issue a stronger form of antihistamine tablet or steroid nasal spray than is available over the counter. In some cases, oral steroid medication may be needed for a short period of time.

For food allergies, it’s particularly important to avoid the specific ingredient which triggers symptoms. Read packaging carefully, and make sure you make allergies clear to restaurants or other people who may be serving you food.

If your allergy is severe, or it’s not clear what food you are allergic to, you may be referred to an allergy clinic for further tests.

For people who have had anaphylaxis or a severe allergic reaction, an injectable ‘pen’ containing adrenaline is prescribed through an allergy clinic. This should be carried at all times for use in case of a reaction. For children, ensure that there is a pen at home and at school. If an anaphylactic reaction occurs, use the pen to inject the adrenaline into the outer thigh and call for emergency medical help.

  • If you have ongoing symptoms of allergies despite using over-the-counter treatments
  • If you are unsure what’s causing your allergies
  • If you have had a severe allergic reaction in the past

If you suspect you are having an anaphylactic reaction, do not call a GP but ring for an ambulance immediately.

Last updated:
10 Nov 2020
Reviewed by:
Dr Rhianna McClymont, Lead GP at Livi