Allergen Immunotherapy (AIT) FAQ (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.
This information should be read and understood before signing the ASCIA Allergen Immunotherapy (AIT) Consent Form, prior to commencing allergen immunotherapy (AIT).
This FAQ is for aeroallergens such as pollen and dust mite and there is a separate FAQ for venom immunotherapy.
Q 1. What is allergen immunotherapy?
Allergen immunotherapy (also known as AIT, desensitisation or allergy ‘shots’) changes the way the immune system reacts to allergens such as pollens and dust mites, by altering the body’s allergic response.
- 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 not a quick fix form of treatment, as it usually requires a commitment of three to five years, to result in five to ten years of tolerance to allergens with fewer or no symptoms. Symptoms may return after this time.
Q 2. What conditions can allergen immunotherapy help?
- Is often recommended for treatment of allergic rhinitis (hay fever), due to pollen or dust mite allergy (and sometimes asthma) when symptoms are severe.
- Is recommended when the cause is difficult to avoid, such as grass pollen.
- Is recommended when medications don't help or cause adverse side effects, or when people prefer to avoid medications.
- Can be given by regular injection (subcutaneous), or by daily oral doses (sublingual). It generally takes at least four to six months to improve symptoms. If an improvement in symptoms is seen, recommended treatment duration is three to five years, to reduce the risk of symptoms returning.
Q 3. What should I expect?
- Allergy medicines can still be used to help manage symptoms while undergoing allergen immunotherapy.
- Allergen immunotherapy only works if high doses are used and is not like homeopathy which claims to cure a variety of medical conditions using extremely weak extracts, a claim for which there is no scientific evidence.
Q 4. What allergen extracts are available in Australia and New Zealand?
- Commercial allergens available for allergen immunotherapy in Australia and New Zealand include:
- Dust mites.
- Pollens from grasses, trees and weeds.
- Animal dander.
- Allergen preparations are normally standardised and labelled by the concentration of protein and/or allergen, expressed as one or more of weight/volume or in-house measures of allergenic reactivity.
- The quality of the allergen is critical for both diagnosis and treatment, therefore only commercially available allergens should be administered.
- Different brands are not interchangeable for treatment.
- Different preparations (such as aqueous or alum adsorbed) are NOT interchangeable for treatment.
- Choice of product after informed discussion between the doctor and person being treated about the most appropriate product for them.
- No government subsidy (possible rebate from some private health funds for TGA registered products).
- A current list of allergen immunotherapy suppliers is available at allergy.org.au/members/allergen-immunotherapy-information
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 in a medical facility under supervision. Patients should stay at the medical facility for 30-45 minutes after an allergen immunotherapy
- For some patients who are not tolerating allergen immunotherapy injections, sublingual immunotherapy (SLIT) may be an option.
Q 6. How often is sublingual allergen immunotherapy taken?
Sublingual allergen immunotherapy preparations are usually taken on a daily basis.
Common methods for taking the allergen preparations:
- Take in the morning on an empty stomach.
- Keep the drops or tablet under the tongue for at least two minutes, then swallow.
- Do not eat or drink anything for 15 minutes.
- Avoid foods that may cut the tongue and increase the likelihood of mouth irritation from the preparations.
- If you forget to take them in the morning, continue treatment the next morning at the usual dosage.
Q 7. 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 serious reactions (such as anaphylaxis) are uncommon. Predicting who might have serious reactions is difficult. Patients are normally 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. It is important to talk to your doctor if starting any new medications while on allergen immunotherapy.
- Taking a non-sedating oral antihistamine before the injection may reduce the risk of side effects and may be recommended by your doctor.
It is important to inform your doctor about any reactions you had after your last injection and any new medications you are taking (such as eye drops, new heart/blood pressure tablets), or if you become pregnant.
Patients who are pregnant (or planning to become pregnant) are not routinely commenced on allergen immunotherapy until after they have given birth.
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.
Q 8. Are there any potential reactions to sublingual allergen immunotherapy?
Common side effects include irritation, minor swelling or itching inside the mouth, and stomach upset/nausea. This can be controlled by temporarily reducing the dose or taking a non-sedating antihistamine beforehand. These side effects generally resolve after the first few weeks.
The risk of potentially dangerous side effects arising from this form of treatment, such as difficulty breathing, is extremely low.
Q 9. Is there anything you can do to reduce the side effects from allergen immunotherapy?
Simple precautions may reduce the risk:
- Asthma must be stable before treatment starts. If an asthma flare occurs during treatment, the injection should be deferred until it is back under control.
- You must tell your doctor if you develop itchy eyes, itchy nose, itchy throat or chest, increased wheezing or if you feel light-headed or faint after an injection. You should never put up with these symptoms.
- Double check with your GP or specialist if you are taking any heart or blood pressure medicines or glaucoma eye drops, as some can increase the risk of side effects.
- If you are on allergen immunotherapy and plan to start a new heart or blood pressure medicine or glaucoma eye drop, tell your specialist or GP.
- If you have ongoing side effects, let your GP and specialist know about it as soon as possible. A few minor changes to treatment may allow you to tolerate it better.
- If you are sick or have a fever, it may be better to delay a dose. Discuss this with your GP or specialist.
Q 10. Are there cases when allergen immunotherapy should not be given?
- Pregnancy: It is normally recommended not to start treatment if you are already pregnant or planning a pregnancy. If you become pregnant while on treatment discuss this with your allergy specialist.
- Breast-feeding: Treatment can be started or continued whilst breastfeeding.
- Age: Allergen immunotherapy is not normally started in children younger than five years of age.
- 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.
Q11. 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.
Immunotherapy to switch off food allergy is in the research stages, it is yet to enter routine clinical practice. People with diagnosed food allergy must avoid the food trigger unless they are participating in a research study lead by a clinical immunology/allergy specialist.
Q 12. What are the costs of allergen immunotherapy?
- There is no PBS or Pharmac rebate for aeroallergens, but Specialist and GP visits attract a rebate (Medicare or Pharmac).
- Patients with private health insurance may get a rebate, but usually only for TGA registered products. Individuals may clarify this with their insurer; the rebate may be under Prescriptions in Health Insurance Extras.
© ASCIA 2023
Content updated June 2023
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