What is allergen immunotherapy?

Allergen immunotherapy can help stop or reduce allergies. It changes your body's reaction to things that can cause allergies (allergens).

An allergic reaction happens when your body's immune system responds to something that is usually harmless.

How does allergen immunotherapy work?

Allergen immunotherapy works by giving your body small amounts of the allergen over a few years. Your immune system slowly 'switches off' so you don't react to the allergen anymore.

Allergen immunotherapy works differently from other allergy medicines. It helps treat your allergies directly. Other allergy medicines work by making your symptoms better.

What forms of allergen immunotherapy are available?

You can get allergen immunotherapy as injections under your skin, or as tablets, sprays or drops placed under your tongue (sublingual administration).

Injection

Your doctor will inject a tiny amount of the allergen under your skin using a small needle. These injections usually don't hurt.

• At first, you usually need an injection every week.
• They slowly increase the dose over 3 to 6 months until they reach a steady dose.
• You will need regular injections, usually once a month, for several years.

Under your tongue

Allergen immunotherapy can be taken under your tongue (sublingually) as tablets, or as sprays or drops.

• You keep the allergen under your tongue for a few minutes and then swallow it.
• You can take this type of immunotherapy at home — there is less chance of side effects.
• This is more expensive and for some types of allergies it isn't as effective as injections.

Symptoms usually start to improve after about 4 to 5 months. You must keep taking the immunotherapy medicine regularly and work closely with your doctor.

Doctors usually recommend continuing the treatment for 3 to 5 years to prevent the allergies from returning.

While you are having allergen immunotherapy, continue to take your allergy and asthma medicines as usual — your doctor will guide you.

A doctor who specialises in allergies, like a clinical immunologist or allergy specialist, should always supervise allergy immunotherapy.

Which allergies can allergen immunotherapy treat?

Allergen immunotherapy may be recommended to treat life-threatening allergies to stinging insects like:

• bees
• wasps
• jack jumper ants

It may also be recommended for:

• hay fever (allergic rhinitis) — caused by pollen or dust mite allergy, when your symptoms are serious and medicines aren't working well
• asthma — if you know your symptoms are caused by a specific allergen that's hard to avoid
• eczema — in rare cases

Researchers are studying allergen immunotherapy to switch off food allergies. People with diagnosed food allergies need to stay away from the food that causes their allergy unless they are in a research study or program.

How well does allergen immunotherapy work?

Many people with hay fever who get immunotherapy will see an improvement in their symptoms. Most people also have a better quality of life after getting allergen immunotherapy.

Allergen immunotherapy can help with asthma if you know which allergen is making your asthma worse. It might reduce your chances of developing asthma if you have hay fever.

Research shows that allergen immunotherapy is very effective in lowering the chance of serious reactions from insect stings.

What are the risks of allergen immunotherapy?

Injections

Some people notice swelling at the injection site.

The greatest risk is a severe allergic reaction (anaphylaxis), but this is very rare.

After your allergen immunotherapy treatment:

• you will have to stay in your doctor's surgery for 30 minutes
• you must not exercise for a few hours

Under the tongue (sublingual)

If you are taking sublingual immunotherapy, you might notice a little swelling or itching in your mouth, or you could have diarrhoea.

Serious side effects are rare.

Taking an antihistamine before treatment may reduce your chances of side effects.

When should I see my doctor?

Anaphylaxis needs immediate treatment with an injection of adrenaline. If you or someone with you is having an anaphylactic reaction and they have an adrenaline autoinjector (brand names include EpiPen and Anapen), give them a shot of adrenaline.

Learn about first aid for anaphylaxis and how to use an adrenaline autoinjector.

Visit your doctor if you have mild or moderate allergy symptoms. You can get treatments and do things to help.

Resources and support

For more information about allergen immunotherapy visit Australasian Society of Clinical Immunology and Allergy (ASCIA).

Visit Allergy Anaphylaxis Australia for information and support on treatment of allergy.

You can also call the healthdirect helpline on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak with you 24 hours a day, 7 days a week.