For people whose allergy symptoms are difficult to control — or whose allergens are simply impossible to avoid — allergen immunotherapy (AIT) offers something that antihistamines and nasal sprays cannot: the chance to change the way the immune system responds to allergens in the first place.
Here’s what AIT involves, who it’s suitable for, and what to expect from treatment.
What is allergen immunotherapy?
Allergen immunotherapy — sometimes called desensitisation — works by exposing the immune system to gradually increasing doses of an allergen over time. With consistent treatment, the immune system learns to tolerate the allergen rather than overreact to it.
It is a long-term commitment. Treatment typically continues for at least three years, but the results can be lasting — many people experience five to ten years of significantly reduced symptoms, or no symptoms at all, after completing a course.
AIT is a proper medical treatment and is entirely different from homeopathy. It works because it uses high doses of standardised allergen preparations. Homeopathy uses extremely weak extracts and has no scientific evidence to support its claims.
How is it given?
There are two main ways to receive allergen immunotherapy.
Subcutaneous immunotherapy (SCIT) involves regular injections, usually given at a clinic. Treatment begins at a very low dose and increases gradually — typically over weekly appointments — until an effective maintenance dose is reached. This usually takes three to six months. After that, injections are generally given monthly and require a 30–45-minute observation period at the clinic afterward.
Sublingual immunotherapy (SLIT) involves daily doses taken at home as tablets, sprays, or drops placed under the tongue. This option suits people who prefer not to have injections or find regular clinic visits difficult to manage. SLIT tablets are taken before breakfast and before brushing teeth — you place one tablet under the tongue, allow two minutes for it to dissolve, then dry swallow and wait five minutes before eating, drinking, or brushing your teeth.
Both approaches require consistency to be effective. Missing doses regularly reduces the benefit of treatment.
What conditions does it treat?
AIT is most commonly used for:
- Allergic rhinitis (hay fever) caused by grass pollen, dust mites, or other aeroallergens — particularly when symptoms are severe, hard to manage with medication, or caused by something unavoidable like grass pollen
- Allergic asthma associated with dust mites or pollen, in some cases
- Animal dander and mould allergies where avoidance is not practical
Allergen preparations available in Australia cover dust mites, grass, tree and weed pollens, animal dander, and moulds.
AIT is not a treatment for food intolerance or reactions to food chemicals, additives, or preservatives. It is also not routinely used for eczema. Food oral immunotherapy (OIT) — which addresses food allergy — is a separate treatment; you can read more about that on our OIT page.
Who is it suitable for?
AIT is usually initiated by an Immunologist or GP Allergist after confirming the cause of your allergies through testing.
It is generally recommended when:
- Symptoms are significantly affecting quality of life
- The allergen is difficult or impossible to avoid
- Medications aren’t providing adequate relief, or are causing unwanted side effects
- You would prefer a longer-term solution over ongoing medication
There are some situations where AIT is not appropriate, or needs to be approached carefully:
- Pregnancy — it is generally recommended not to start a new course of AIT during pregnancy. If you fall pregnant while already on treatment, speak with your specialist. Treatment can be started or continued while breastfeeding.
- Unstable asthma — asthma should be well controlled before starting. If you have a flare, treatment may need to be paused until it settles.
- Certain medications — some heart and blood pressure medicines, and some glaucoma eye drops, can increase the risk of side effects. Let your specialist and GP know what you are taking before starting.
What are the risks?
As with any treatment that involves deliberate allergen exposure, reactions can occur.
With injections, localised swelling at the injection site is fairly common and can be managed with antihistamines, ice, or paracetamol if needed. More serious reactions such as anaphylaxis are uncommon, but this is why patients are observed for at least 30 minutes after each injection and advised avoiding vigorous exercise for at least three hours afterward.
With sublingual preparations, mild irritation of the mouth, tongue, or throat is common when starting treatment — this is simply the body’s response to the allergen and usually settles as treatment continues. Generalised allergic reactions are rare but possible. If you experience hives, breathing difficulty, or any digestive symptoms such as difficulty swallowing, stop taking your tablets and seek medical attention immediately.
For both forms of AIT, it is important to let your specialist know about any reactions after a dose, any new medications you have started, and if you become pregnant.
Taking the next step
Allergen immunotherapy is a meaningful investment in long-term health — not a quick fix, but for the right patient, a genuinely life-changing one. The team at Austral Allergy sees patients across our Canberra and Adelaide clinics and can assess whether AIT is appropriate for your situation.
If you would like to explore whether allergen immunotherapy is right for you, we welcome you to arrange an appointment https://canberraallergy.com.au/
Clinics will soon be coming to Melbourne and the Northern Rivers.
https://www.allergy.org.au/patients/allergy-treatments/allergen-immunotherapy