June 15, 2015



An allergy is when your body’s immune system reacts to normally harmless substances that it sees as harmful. The allergy-causing substances are called allergens.

Your body’s immune system is a natural defence against infection and other foreign material. If you are allergic to something, your immune system will react every time you come into contact with that allergen.

Causes of allergies

Many substances can cause an allergic reaction, but some of the most common are:

  • pollen
  • mould
  • animal hair
  • dust and dust mites
  • latex
  • medicines
  • insect stings
  • foods.

Children and allergies

Allergies are common in childhood and may begin with the development of food allergies in children under 12 months old. Milk (dairy), eggs and peanuts are the most common food allergies in this age group, but fish, shellfish, tree-nuts, sesame, kiwifruit, wheat and soy can also be a problem.

Many children grow out of their food allergies in late childhood, although allergies to peanuts, tree-nuts, fish and shellfish tend to remain.

Eczema, which affects up to a third of children under 12 months of age, is related to the development of food allergies but may also be triggered by non-food allergens (things that trigger allergies) such as house dust mites. Most children with eczema do not have food allergies, but most children who have food allergies have eczema.

Allergies often run in families, but not every family member may be allergic to the same thing. Children living in homes with smokers are more likely to develop asthma.

Kinds of allergic reaction


Different allergens will cause different kinds of allergic reactions. The most common allergic conditions are hay fever, asthma and skin problems (eg, eczema, rashes, hives).

  • Airborne allergens such as mould, dust, pollen, grasses and weeds can cause hay fever.
  • Pollens, moulds and house dust can trigger asthma attacks.
  • Skin reactions can be caused by contact with an allergen (like latex or certain metals), by insect bites or stings, or by eating food or taking medicine you are allergic to.

The symptoms of an allergic reaction depend on the type and severity of the reaction.

Common symptoms include:

  • sneezing
  • watery and/or swollen eyes
  • stuffy or runny nose
  • itching
  • a rash or hives (raised red itchy areas on the skin)
  • stomach cramps
  • diarrhoea.

A fast pulse and nausea and/or vomiting are less common reactions.

When to call an ambulance


Sometimes an allergic reaction may be severe. This is called anaphylaxis. Anaphylaxis is a life-threatening emergency, which can affect breathing and circulation within minutes.

Call 111 straight away if you or a family member has an allergic reaction with any of these symptoms:

  • trouble breathing, including wheezing
  • swelling of lips or tongue
  • pale, cool, damp skin
  • drowsiness, confusion or loss of consciousness.

Insect stings, drugs such as penicillin, and certain foods are some of the more common causes of severe allergic reactions.

When to see your doctor

See your doctor if you or a family member has allergy symptoms that are causing you problems or you are worried that the allergy might be severe.

Your doctor will ask about your history of symptoms and examine you. To identify a food allergy your doctor may suggest that you avoid the food for a while, then try eating it again to see if your symptoms return.

Your doctor may do a skin scratch or prick test, which will check for reactions to tiny amounts of possible allergens placed under your skin. Blood tests can also help identify what you are allergic to.

Call us on 5422450 or Healthline 0800 611 116 if you are unsure what you should do.

For mild symptoms

Mild symptoms may not need treatment. A variety of over-the-counter pharmacy medicines can help with allergy symptoms, including decongestants and antihistamines.

For more severe symptoms

For more severe symptoms, your doctor may prescribe steroid medication or quick-acting inhaled bronchodilators and/or other medicine to treat breathing problems.

Immunotherapy is another possible treatment designed to make you less sensitive to an allergen so you don’t react to it so strongly. This involves injecting you with tiny but increasing amounts of the allergen. The treatment phase can last up to 6 months, followed by a maintenance phase for 2–3 years or longer.

Epi-pen emergency kits may be prescribed by your doctor for severe reactions. The epi-pen is a ready-to-use syringe of adrenaline, which is essentially designed to keep you alive until you get to hospital. Teach family members, friends and work colleagues about how to use an epi-pen and make sure they know that you must also get to hospital straight away.


If you have an allergy, you should avoid the thing you are allergic to, like by not eating or touching it.

Airborne allergens like pollen and dust mites can be especially hard to avoid. 

Cigarette smoke can make hay fever and asthma worse. Not smoking and not being around smokers can help.

Preventing allergies from developing

There is no known way to prevent allergies – however, some research has shown that breastfed babies may be less likely to develop allergies and asthma. Children who live in smokefree homes are also less likely to develop asthma.


Asthma and allergies

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Some asthma is caused by allergies.

The most common allergens that cause asthma are:

  • dust mites
  • dander from animals (skin, scales and fur)
  • rodent urine
  • insect debris
  • food dust
  • pollens
  • moulds.

Allergy tests

There are tests to find out whether your asthma might be caused by an allergy, such as a skin prick test or blood test.

Skin prick tests are generally not used for children under the age of 3, as they don’t give reliable results in young children.

For more information about testing, talk to your doctor. 

Dust mites


Dust mites are a common allergen that cause asthma. They’re found in every home.

There are some things you can do to cut down your exposure to dust mites and their droppings:

  • Get bedding covers that provide a barrier to dust mites. (This is the single most effective measure you can take.)  Contact your localAsthma Society to find out where you can get these covers.
  • Consider removing as much fitted carpet as possible, especially in the bedrooms.
  • Vacuum cleaners won’t get rid of dust mites, but they do suck up dust mite droppings. Vacuum at least once a week and if possible, use a HEPA filter system in your vacuum cleaner.
  • Dust regularly with a damp cloth.
  • Hang your washing in the sun to dry, rather than using the dryer.
  • Air blankets and loose rugs on the washing line regularly.
  • Try not to store things under the bed or on top of wardrobes.

For children with asthma:

  • Put their soft toys in the deep freeze for at least 24 hours every 3 weeks. Use washable soft toys and avoid fluffy toys if possible.
  • Avoid using sheepskins (especially for a baby’s bedding).
  • Don’t put young children on a bottom bunk.



Wind-pollinated plants tend to be more likely to trigger asthma than plants that are pollinated by insects or birds. 

Problem plants include pines, oaks, wattles, birches, grasses, plantains, olives and privets.

Flowers such as daisies, marigolds and chrysanthemums can also be triggers.

Here are some tips to help reduce your exposure to pollen:

  • Use pollen forecasts to help you work out when you may be at risk.
  • Stay indoors, if possible – particularly on windy days when the pollen count is high.
  • Keep windows closed when the pollen count is high, especially when you’re in the car.
  • Get someone else to mow your lawns and trim your hedges.
  • Avoid organic mulches: use gravel mulch instead. Be careful with potting mix as breathing in mould spores can be an asthma trigger. 

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