Allergies

Allergies are very common, affecting about 1 in 3 New Zealanders at some time in their lives.

Key points:

  1. An allergy happens when a person’s immune system overreacts to substances called allergens in the environment. Your body treats an allergen as an invader and begins to create antibodies against it.
  2. Common allergens include house dust mites, grasses, pollen, pets, foods, some medicines, insect stings, latex and moulds. 
  3. Symptoms of allergies range from mild hayfever (runny nose and itchy eyes) to potentially life-threatening, or anaphylactic See below about what to do in an emergency.
  1. Allergies are common, however with treatment most people can manage their allergies with minimal problems.
  2. Children have more allergies than adults. As our immune system matures, some allergies disappear, eg, in some food allergies.
  3. The best way to prevent symptoms is to avoid what triggers your allergy. Talk with your healthcare team to find out what other treatments will help such as nasal sprays, antihistamine tablets and eye drops.

Anaphylaxis is a severe allergic reaction and must be treated as a medical emergency, requiring immediate treatment and urgent medical attention. If you or someone you care for experiences symptoms of anaphylaxis below, give adrenaline (EpiPen) if available and call 111 for an ambulance.

  • swelling of tongue
  • tightness in throat
  • difficulty breathing or wheezing
  • difficulty talking or hoarse voice
  • dizziness or collapse
  • pale and floppy (in young children).

What is an allergic reaction?

When you have an allergy, your immune system overreacts to a substance that, to most people, is harmless. Your body’s immune system treats the substance (known as an allergen or trigger) as an invader. To defend itself against the allergen, your body produces antibodies called immunoglobulin E (IgE). These antibodies cause certain cells in the body to release chemicals such as histamine into your bloodstream in an attempt to fight off the invader.

The release of these chemicals causes an allergic reaction. Symptoms vary according to the part of the body affected, but can include sneezing, watery eyes, itching, rash, and raised weals or hives on your skin. Extreme allergic reactions can be life-threatening and needs immediate treatment. This is called anaphylaxis.

What are the causes of allergies?

While you don’t inherit an allergy directly, you may inherit a tendency to be allergic and develop allergic diseases. This tendency is called being atopic. Allergies start only if you are  exposed to an allergen. Once you develop a sensitivity to an allergen, an allergic response is set off every time you are exposed to the allergens that affect you. 

What are the common allergens?

Substances in the environment that can cause an allergic reaction are called allergens. A very common indoor environmental allergen is the dust mite or, to be more precise, its droppings. Other common allergens include:

  • pollen, particularly from grass, trees and weeds
  • animal dander (skin, scales or flakes from animals)
  • metals such as nickel in watch-bands, earrings or belt buckles
  • latex in rubber products
  • some moulds
  • insect bites and stings
  • household chemicals such as those in hair dyes and detergents
  • medicines
  • foods such as peanuts, dairy, eggs and seafood.

True food allergies are not common and most reactions to food are more likely to be food intolerance which doesn’t involve your body’s immune system rather than an allergic reaction that involves your body's immune system. Read more about the difference between food allergies and food intolerance.

Cigarette smoke is often considered a cause but it is actually an irritant rather than an allergen. That means it doesn’t cause an allergy, but makes an existing allergy worse.

What are the types of allergic conditions?

Depending on the type of allergens and where allergens enter your body, they can cause different allergic reactions and allergic conditions. These include:

  • allergic rhinitis (hayfever)
  • eczema or atopic dermatitis
  • allergic contact dermatitis
  • allergic conjunctivitis
  • asthma
  • food allergies
  • anaphylaxis (severe allergic reaction).

What are the symptoms of an allergic reaction?

Symptoms depend on where allergens enter your body and which part of your body is affected. They can range from mild to severe. Typically, symptoms happens within minutes to an hour after you are exposed to a particular allergen.

  • Hayfever (also known as  allergic rhinitis) affects the eyes and nose when allergens are inhaled. Symptoms include sneezing,  runny nose, watery and itchy eyes, irritated and itchy throat and sometimes, a stuffy, blocked nose.
  • Allergic contact dermatitis is a condition which is caused by your skin coming into contact with an allergen, such as nickel. Symptoms include  red, scaly skin that itches.
  • Allergies to some foods, insect bites or stings can cause urticariaor hives) which are raised red, itchy patches on the skin, and other symptoms such as nausea or vomiting, swelling around your lips, face and eyes, diarrhoea or sneezing.
  • Anaphylaxis is a severe allergic reaction. It can involve your whole body and is a life-threatening condition. It requires immediate life-saving medicine such as adrenaline. Read more about anaphylaxis.

Anaphylaxis is a severe allergic reaction and must be treated as a medical emergency, requiring immediate treatment and urgent medical attention. If you or someone you care for experiences symptoms of anaphylaxis below, give adrenaline (EpiPen) if available and call 111 for an ambulance.

  • swelling of tongue
  • tightness in throat
  • difficulty breathing or wheezing
  • difficulty talking or hoarse voice
  • dizziness or collapse
  • pale and floppy (in young children).

How are allergies diagnosed?

It's important to talk to your doctor if you think you or your child may have an allergy to something. There are many causes of allergies and some symptoms may be due to other conditions.

Your GP or doctor will ask you or your child about some allergic symptoms such as a rash or an upset stomach, and its relation to the types of allergen. Other questions include:

  • When do your symptoms occur when exposed to a particular allergen?
  • How often do your symptoms occur?
  • Is there anything that will trigger your symptoms?
  • Are there any family members who also have allergies?
  • Have you been exposed to new foods, pets or medicines recently?

If you have allergic symptoms to a particular allergen, your doctor will also check whether you have symptoms of anaphylaxis, a severe allergic reaction to a particular allergen. It can involve your whole body and is a life-threatening condition. It requires immediate life-saving medicine such as adrenaline. Read more about anaphylaxis.

In some cases, it is easy to identify which allergen is causing your reaction when symptoms appear rapidly after you are exposed to a particular allergen. However, if the cause is unknown, other diagnostic tests may be needed.

Your GP may refer you or your child for a skin prick test or a blood test to test for the presence of an antibody (IgE) that causes an allergic reaction. Your doctor may also refer you or your child to a paediatric clinic or allergy specialist for further tests if it is still unclear about the cause.

Skin prick tests

  • A needle is pricked into your skin through a drop of the suspected allergen, usually on the skin of your inner forearm or back.
  • The size of the weal on your skin indicates how strongly you are allergic to a particular allergen.
  • As many as 30 allergens can be tested at the same time to help identify the particular substances to which you are allergic to.

How are allergies treated?

Treatment depends on the type of allergies you have. The most important part of managing allergies is to avoid allergens if possible. Allergic symptoms also have specific treatments, including medicines and self-help measures. For some allergic conditions such as allergic rhinosinusitis, allergen immunotherapy (AIT) can also help.

Self-care measures

Some self-care measures you can do to help manage your allergies include:

  • avoidance of allergens that can trigger your symptoms
  • wearing a medical bracelet stating you are allergic to a particular allergen
  • always reminding your healthcare team that you have an allergy when receiving medicines from them
  • if you are at risk of anaphylaxis and have been prescribed an EpiPen, always carry them and your allergy action plan.

Read more about how can I care for myself with allergies.

Medicines

Medicines are used to treat allergic symptoms, these include:

  • antihistamines
  • steroid tablets
  • steroid nasal inhalers or decongestant nasal spray
  • medicated or non-medicated eye drops
  • emollient or corticosteroid creams
  • adrenaline – usually in an autoinjector called EpiPen.

Antihistamines

  • Antihistamines are medicines that reduce or block histamines, the substance released by our bodies in response to allergens.
  • Antihistamines are usually well-tolerated and work well.
  • Antihistamines can be bought from pharmacies or prescribed by your doctor. Ask your pharmacist/chemist or doctor if you are unsure.
  • They are most commonly used to treat allergic symptoms.
  • Read more about antihistamines.

Steroid tablets

  • Steroid tablets can also be used to treat allergic symptoms such as hives and reduce inflammation.
  • A prescription by your doctor is required to get steroid tablets.
  • Read more about steroid tablets.

Steroid nasal inhalers or decongestant nasal sprays

  • These are used to relieve symptoms of allergic rhinitis or hayfever.
  • A prescription may be required for stronger dose of steroids.
  • Decongestant nasal sprays can relieve stuffiness or congestion of your nostrils, and can be bought over-the-counter. However, these medicines are not suitable for long term use. Ask your pharmacist or doctor if you are unsure.
  • Read more about steroid nasal sprays and decongestant nasal sprays.

Medicated or non-medicated eye drops

  • There are eye drops which may be helpful in some allergic conditions such as allergic conjunctivitis.
  • These eye drops can be lubricating eye drops or some can contain steroids.
  • Ask your doctor or pharmacist to find out suitable eye drops for you.
  • Read more about eye drops.

Emollients and corticosteroid creams

  • Emollients or corticosteroid creams can be useful to improve allergic symptoms or conditions that involve your skin, such as hives or eczema.
  • Read more about emollients and corticosteroid creams.

Adrenaline

  • Adrenaline is used in an emergency to treat anaphylactic symptoms.
  • It is usually in the form of an autoinjector, called EpiPen.
  • EpiPen is easy to use and can be given by non-medical people.
  • If you have been prescribed an EpiPen, your doctor or pharmacist can teach you how to use it.
  • Read more about EpiPen.

Talk to your doctor or pharmacist about advice and the right medicines for your particular symptoms or conditions.

Allergen immunotherapy (AIT)

When medicines don’t provide enough relief another option is immunotherapy. Immunotherapy may also be an option if your symptoms are severe and the allergen is difficult to avoid, eg, in allergic rhinosinusitis or allergic conjunctivitis. 

Immunotherapy works by changing the way your immune system reacts to allergens. Your doctor will administer an allergen you are allergic to into your body over a period of 3-5 years. The aim of immunotherapy is to make you develop tolerance to a particular allergen. Not everyone is suitable for immunotherapy, ask your doctor or an allergy specialist about whether you are suitable for immunotherapy. Immunotherapy can be given under the tongue, nasally or by an injection.

How can I care for myself with allergies?

It is not always practical to avoid the allergens you are allergic to, your doctor or nurse can teach you how to do that. However, some things you can do include:

  • being careful about what you eat if you have food allergies
  • avoiding exposure to pets if you have animal allergies
  • keeping your home warm and dry if you have mould allergies
  • staying indoors and avoiding grassy areas if you have allergic rhinitis or hayfever.

People who are at risk of life-threatening allergic reactions need to carry adrenaline with them at all times and be trained in the correct use of an adrenaline auto-injector, eg, EpiPen. For children with allergies, parents or caregivers should also be familiar with how to use the EpiPen. Partners of adults should also be familiar with these devices. It is also important to carry your allergy action plan at all times or put your action plan somewhere accessible easily in your homes.

Wearing a medical bracelet stating what you are allergic to can be very helpful for doctors and other health professionals when treating you.

Always remind your doctor or pharmacist of your allergies before starting any new treatment, including complementary or herbal medicines.

Allergic reaction action plan

Allergic reaction action plan is a written document that outlines what you need to do or follow if you have an allergic reaction. Allergic reactions can cause a variety of symptoms ranging from mild , moderate reactions, to severe and life-threatening reactions (anaphylaxis). Having an action plan such as those listed below filled out by your doctor gives you a symptom and treatment guide to follow. Here are two plans from the Australasian Society of Clinical Immunology and Allergy (ASCIA).

It is important that you and your family are able to recognise the signs of an allergic reaction and anaphylaxis and know what to do in an emergency. If you don’t have an action plan, ask your doctor to fill out one with you.

How can I prevent an allergic reaction?

The best way to prevent an allergic reaction is to identify the substances that trigger your allergy and try to avoid them. Here are some tips to avoid some common allergens and help minimise allergic symptoms.

Dust mites

You can never get rid of all the dust mites in your house, but these measures can help reduce their numbers:

  • If possible, replace wall-to-wall carpets with hard flooring such as floorboards.
  • Clean non-carpeted floors with a wet or electrostatic mop rather than using a vacuum cleaner.
  • Clean carpets 2-3 times each week with a vacuum cleaner that has a suitable filter.
  • Dust surfaces with a damp or electrostatic cloth 2-3 times weekly.
  • Remove fluffy, stuffed toys from your child's bedroom or wash them weekly in hot water (putting soft toys in the freezer overnight kills mites but does not remove allergen).
  • Remove soft, upholstered furniture from the bedroom.
  • Select furniture that is upholstered in vinyl or leather rather than cloth.
  • Ensure good ventilation throughout your house to avoid moist air build-up. If practical, try to sleep with windows open to reduce the amount of moisture in the bedroom from breathing.

Pollen

  • Keep the garden free of highly allergenic plants.
  • Try to stay indoors at times when the pollen count is at its highest, eg, the early evening.
  • Get someone else to mow your lawn.
  • Close your bedroom windows at night to prevent pollen entering.
  • Wear wrap-around sunglasses to avoid pollen getting into your eyes.
  • Have a shower and wash your hair at night to wash away pollen you may have 'collected' during the day.

Animal dander

Don't keep pets, or at the very least, keep them outside.

Skin allergies

Avoid strong soaps, perfumes and household cleansing products that may irritate sensitive skin.

Insect bites and stings

  • Make sure you wear footwear outdoors.
  • Cover your limbs.
  • Don't make sudden moves when bees or wasps are around.
  • Avoid strong perfume as it can attract insects.
  • Take care in the garden – wear gloves when gardening.
  • Use insect repellant.

Food allergies

If you have food allergies, know what they are and avoid those foods, however, take care to maintain a balanced diet. A consultation with a nutritionist or dietitian can be very helpful. Ask your doctor for a referral to a dietitian.

What support is available with allergies?

Allergy New Zealand provides information, education and support for people with allergy, parents of children with allergy, teachers or healthcare professionals. Find out more on their website.

Learn more

The following links provide further information about allergies. Be aware that websites from other countries may have information that differs from New Zealand recommendations.   

A-Z Allergies Allergy NZ
Allergy FAQs  Allergy NZ
Allergies Ministry of Health, NZ
Allergy KidsHealth NZ
Allergies HealthInfo Canterbury, NZ
What is allergy? The Australasian Society of Clinical Immunology & Allergy
Allergies NHS, UK
Allergies Patient Info, UK
Allergies factsheet in multiple languages Health info translations

References

  1. Allergies Auckland Regional HealthPathways, NZ, 2020
  2. Calderon MA, Alves B, Jacobson M, Hurwitz B, Sheikh A, Durham S. Allergen injection immunotherapy for seasonal allergic rhinitis. Cochrane Database of Systematic Reviews 2007, Issue 1. Art. No.: CD001936. DOI: 10.1002/14651858.CD001936.pub2.
  3. Assessing the efficacy of immunotherapy for desensitisation of peanut allergy in childrenThe Lancet, Volume 383, Issue 9925, Pages 1297 - 1304, 12 April 2014. doi:10.1016/S0140-6736(13)62301-6
  4. Personal action plans for allergies.Produced by the Australasian Society of Clinical Immunology and Allergy (ASCIA)
Credits: Health Navigator, May 2014. Reviewed By: Editorial team Last reviewed: 07 Mar 2015