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Allergen Immunotherapy (AIT)

Frequently Asked Questions

This document has been developed by ASCIA, the peak professional body of clinical immunology/allergy specialists in Australia and New Zealand. ASCIA information is based on published literature and expert review, is not influenced by commercial organisations and is not intended to replace medical advice.

For patient or carer support contact Allergy & Anaphylaxis Australia or Allergy New Zealand.

This information should be read and understood before signing the ASCIA Allergen Immunotherapy Consent Form and starting allergen immunotherapy (AIT). This FAQ is for allergens such as pollen and dust mite. There is a separate FAQ for venom immunotherapy. This FAQ is for aeroallergens such as pollen and dust mite and there is a separate FAQ for venom immunotherapy.

pdfASCIA PC Allergen Immunotherapy FAQ 2024162.74 KB

pdfASCIA Allergen Immunotherapy Consent Form186.65 KB

Q 1: What is allergen immunotherapy?

Allergen immunotherapy (also known as AIT or desensitisation) changes the way the immune system reacts to allergens such as pollens and dust mites.

Allergen immunotherapy:

  • Involves the regular administration of gradually increasing doses of commercially available allergen preparations, usually over a period of years.
  • Can be given as regular injections (subcutaneous), or as daily oral doses of tablets, sprays or drops under the tongue (sublingual).
  • Is a long term treatment and usually takes at least three years. This can result in five to ten years of tolerance to allergens with fewer or no symptoms.
  • Only works if high doses are used and is therefore different to homeopathy. Homeopathy claims to cure a range of medical conditions using extremely weak extracts and there is no scientific evidence to support this.

Allergy medicines, such as antihistamines and intranasal corticosteroid sprays, can be used to help manage symptoms when receiving allergen immunotherapy.

Q 2: When is allergen immunotherapy recommended?

Allergen immunotherapy is:

  • Often recommended for treatment of allergic rhinitis (hay fever), due to pollen or dust mite allergy (and sometimes asthma) when symptoms are severe.
  • Recommended when the cause is difficult to avoid, such as grass pollen.
  • Recommended when medications do not help or cause adverse side effects, or when people prefer to avoid medications.
  • Usually initiated by a clinical immunology/allergy specialist.

Before starting allergen immunotherapy:

  • Asthma should be stable. If an asthma flare occurs, treatment should be delayed until it is back under control.
  • Check with your specialist and GP if you are taking any heart or blood pressure medicines or glaucoma eye drops, as some can increase the risk of side effects.

Q 3: When should allergen immunotherapy not be given?

  • Pregnancy. It is normally recommended not to start treatment if you are pregnant or planning a pregnancy. If you become pregnant while on treatment discuss this with your allergy specialist. Treatment can be started or continued whilst breastfeeding.
  • Arm lymphoedema (swelling) after breast cancer surgery. If a lymph node dissection has been done on one arm, then do not give injections on that side. If injections can’t be given in either arm, the injections can be given elsewhere, such as the leg or under the skin of the stomach.

Q 4: What aeroallergens are available for immunotherapy in Australia and New Zealand?

  • Allergen immunotherapy products available in Australia and New Zealand include:
    • Dust mites
    • Pollens from grasses, trees, and weeds
    • Animal dander
    • Moulds
  • Allergen immunotherapy products are normally standardised and labelled by concentration of protein and/or allergen as weight/volume and/or measures of allergenic reactivity.
  • The quality of the allergen is critical for both diagnosis and treatment, so only commercially available allergens should be used.
  • Different brands and preparations (such as aqueous or alum adsorbed) cannot be interchanged.
  • There is no government subsidy but there may be rebates from some private health funds for TGA registered products.
  • A current list of allergen immunotherapy suppliers is available at

Q 5: How often are allergen immunotherapy injections given?

  • Injections start with a very low dose. A small needle is used which may be uncomfortable, but not painful.
  • Doses are gradually increased on a regular (usually weekly) basis, until an effective maintenance dose is reached. It usually takes three to six months to reach an effective maintenance dose.
  • Once the maintenance dose is reached, injections are usually administered monthly under medical supervision. Patients should be observed for 30-45 minutes after an allergen immunotherapy

Q 6: How often is sublingual allergen immunotherapy taken?

Some patients may prefer sublingual immunotherapy (SLIT) or may not tolerate injections. These preparations are usually taken daily.

Q 7: What is the method for taking sublingual allergen preparations?

It is important to take your SLIT each day to get the best results. To help you remember to take your SLIT each day, you can place the tablets where you will see them and set a phone alert reminder.

When using SLIT tablets: 

  • Place one tablet under the tongue daily, before breakfast and before brushing your teeth.
  • Wait for two minutes to allow the tablet to dissolve, then dry swallow (without water).
  • Then wait for at least 5 minutes before brushing teeth, eating or drinking. Check product information, as the time can vary for different products.

If you forget to take a SLIT tablet:

  • Less than 7 days since your last tablet, continue taking one tablet a day when you remember. Do not take more than one tablet per day to try to catch up.
  • More than 7 days since the last tablet, contact your doctor for instructions.

You may need to skip one or more SLIT tablets (up to 7 days) if you have dental procedures, mouth ulcers or an asthma flare. Contact your doctor for advice.

Q 8: Are there any potential reactions to allergen immunotherapy injections?

Localised swelling at the site of the injection can be treated with non-sedating oral antihistamines or ice packs and, if painful, paracetamol. More severe reactions such as anaphylaxis are uncommon. It is important to inform your doctor about:

  • any reactions you may have experienced after your last injection such as itchy eyes, nose, throat, increased wheezing, or feeling faint or light-headed.
  • any new medications you are taking (such as eye drops, new heart/blood pressure tablets), or plan to start taking.
  • if you become pregnant.
  • If you are sick or have a fever it may be better to delay a dose.

If the patient is on maintenance doses of allergen immunotherapy and then becomes pregnant, the injections can be continued (unless the patient wishes to stop), the supervising specialist must be contacted to discuss relevant safety issues.

As it is hard to predict who will have a reaction, patients receiving allergen immunotherapy injections are usually advised to:

  • Remain in their doctor's surgery for at least 30 minutes after injection.
  • Avoid exercising for at least three hours after treatment.
  • Avoid some heart and blood pressure medications including beta blockers such as metoprolol or propranolol.
  • Taking a non-sedating oral antihistamine before the injection may reduce the risk of side effects.

Q 9: Are there any potential reactions to sublingual allergen immunotherapy?

Localised side effects such as irritation of the tongue, mouth and throat are common, because you are taking a substance you are allergic to. If required, oral antihistamines can be helpful to relieve symptoms. Side effects will usually disappear as treatment is continued, and rarely require you to stop taking your tablets. If any side effects concern you, contact your doctor.

Generalised allergic reactions are rare, but may include urticaria (hives), asthma flare-up or anaphylaxis (severe allergic reaction). Allergic effects in the digestive tract are rare and may cause difficulty swallowing or reflux symptoms. If you notice any of these symptoms, stop taking your tablets and contact your doctor immediately, or go to your local emergency department, or phone an ambulance.

Q 10: Is immunotherapy available for other conditions?

Immunotherapy for inhaled allergens is not in routine practice for the treatment of eczema.

There is no proven role for allergen immunotherapy to reduce the severity of symptoms related to food intolerance or any perceived adverse reactions to food chemicals, additives, preservatives, or artificial colours.

Oral immunotherapy (OIT) to switch off food allergy is being researched and is in some clinical programs led by clinical immunology/allergy specialists. People with diagnosed food allergy must avoid the food trigger unless they are part of a OIT research study or program.

© ASCIA 2024

Content updated April 2024

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