Allergen Specific Immunotherapy (ASIT)

What is allergen specific immunotherapy?

Allergen specific immunotherapy (ASIT), known colloquially as allergy shots or desensitisation shots, is a treatment option for individuals suffering from some types of allergies.

It involves the regular administration of allergens to desensitise your immune system, thereby reducing the symptoms of allergies and reducing the need for medications for those symptoms.

It is important to note that it is not a complete cure, but can significantly alleviate symptoms by correcting the underlying allergy.

Immunotherapy can be taken as an injection under the skin (subcutaneous) or as tablets, sprays or drops under the tongue (sublingual).

Who can benefit from Allergen Specific Immunotherapy (ASIT)?

ASIT is commonly used to treat allergies caused by:

  • Pollen (eg: grass, tree and weed pollens)
  • House dust mites
  • Pet dander
  • Mould spores
  • Bee and wasp venom

It is often recommended for individuals with:

  • Moderate-severe allergic rhinitis (hay fever)
  • Allergic asthma
  • Bee and wasp venom allergy

Frequently Asked Questions

ASIT works on many different parts of the immune system response over a long period of time. The typical process of commencing ASIT is as follows:

  1. Identification of allergens: Before starting ASIT, it is important to identify and confirm the specific allergens triggering your symptoms through allergy testing.  This is typically done by skin prick and/or blood testing.
  2. Customised treatment: The term “specific” in ASIT is very important. Different people are allergic to different allergens. It is important the immunotherapy administered to an individual is specifically targeting the allergic drivers for that patient. Your doctor will develop a plan including which allergens are to be targeted and the dosage schedule.
  3. Gradual de-sensitisation and immune system response: ASIT involves regular administration of the immunotherapy, typically administered under the skin, but can be done under the tongue. Through regular doses, your immune system learns to tolerate the allergen without triggering an allergic reaction. This process is known as de-sensitisation.
  4. Reduced allergic symptoms: With continued treatment, many patients experience a reduction in the severity of their allergic symptoms. Some may even achieve long-term remission from allergies.

Localised swelling at the site of the injection is very common in patients on subcutaneous immunotherapy. Oral antihistamines (e.g: Telfast) and ice packs to the area can help reduce the itch and swelling. If the swelling is significant, your doctor may need to reduce the next dose.

More severe reactions (such as anaphylaxis) are rare.  Approx 0.005% patients on subcutaneous immunotherapy will have an episode of severe anaphylaxis due to the injection.  These severe reactions can happen at any stage throughout the course of your immunotherapy.

All patients are advised to:

  • Stay under observation for at least 30-minutes after each shot.
  • Avoid exercise for at least 3-hours after your injection.
  • Avoid beta blocker medication (eg: metoprolol or propranolol)
  • Inform their doctor if they are experiencing a flare of their asthma

To help reduce side effects, you may take an antihistamine (e.g: Telfast) 30-minutes prior to your shot.

Immunotherapy products contain the allergen/s of interest that the patient is allergic to. Preservatives may be added to some products to help lengthen shelf life. Allergens within some immunotherapy products have been modified to help reduce the risk of allergic side effects of the ASIT.

ASIT is typically given for 3-to-5 years. Those who receive it for shorter periods are more likely to get a rapid recurrence of symptoms.

After 3-5 years of immunotherapy, we typically suggest ceasing your immunotherapy. 

Relapse rates after ceasing immunotherapy has not been thoroughly studied, but in asthma patients who have received at least 3-years of appropriate immunotherapy, around half will get significant asthma recurrence over a further 3-year period. 

In a study of hay fever sufferers allergic to grass pollen, those who received 3-4 years of immunotherapy had good overall control of their symptoms for at least 3-years after ceasing immunotherapy.

It is important to note that ASIT is not a cure for allergic asthma or hay fever. The goals are a reduction in the frequency and severity of symptoms, along with a reduction in medications needed to control symptoms.

For asthma, studies have shown a moderate reduction in asthma symptoms scores, and it would have been necessary to treat 3 patients with immunotherapy to avoid one deterioration in asthma symptoms.  Overall, it would have been necessary to treat 4 patients with immunotherapy to avoid one requiring increased medication.

For grass pollen related hay fever, studies have shown a moderate reduction in symptom scores, with a moderate reduction in medications required to treat the hay fever.

You can typically expect to start seeing improvement after 4-5 months of immunotherapy.  It is important to continue your immunotherapy for the recommended duration however, as people with only 1-2 years of immunotherapy are more likely to get a rapid recurrence of symptoms.

ASIT is typically not commenced in pregnant women or those actively attempting to conceive. If you are on long term maintenance immunotherapy and have been receiving the injections without reactions, then you should have a discussion with your doctor about the risks and benefits of continuing immunotherapy.

Take back control – start your journey today.

We are a leading paediatric and adult Allergy, Immunology and Immunopathology group with clinics in the Sydney CBD and Westmead.

Our specialists hold sub-specialised qualifications in allergy and immunology, and pathology, and offer significant clinical experience.

If you have a question about a condition or treatment, or would like to book an appointment, please contact us and we will be happy to assist you.