Immunotherapy (also called desensitisation) is a treatment for some allergies, which involves giving a person gradually increasing doses of the allergen to which they react, over a period of years. This gradually trains the immune system not to react to that allergen, so that a person has no symptoms or reduced symptoms.
Which conditions can immunotherapy help?
Immunotherapy is not suitable for all allergic conditions. Conditions where it is currently used include:
- Hayfever: Many people suffer very distressing symptoms of hay fever (seasonal allergic rhinitis) in springtime. This is due to allergy, usually to the pollens of particular grasses. In some cases, modern testing techniques make it possible to identify which grasses cause a person's allergy. The allergy can then be treated by immunotherapy. Because grass pollens are airborne, they are difficult to avoid and so immunotherapy can make a big difference to people with severe grass pollen allergy. The treatment is generally limited to those who have severe hay fever that is not well controlled with medicines such as nasal sprays and antihistamines. If you suffer from bad hay fever, with symptoms such as sneezing, runny nose and itchy eyes, discuss allergy testing with your doctor. You may be one of the lucky ones who can be helped.
- Dust mite allergy: Immunotherapy is a useful treatment for people with severe dust mite allergy, as dust mites are difficult to avoid.
- Insect bites and stings: Where people have life-threatening allergic reactions to insect venom, they are usually good candidates for immunotherapy and it is recommended. Immunotherapy is available for bee and wasp sting allergy and jack jumper ant allergy. People with severe bee and wasp sting allergies should still carry their EpiPen, even after immunotherapy.
- Animal allergy: Immunotherapy is usually only considered for people with allergy to animals who have occupational exposure, such as veterinary surgeons and nurses.
Which conditions can’t be treated by immunotherapy?
- Tick allergy: At present immunotherapy is not available for people who have severe allergic reactions to tick bites.
- Mosquito bites: These do not usually cause generalised allergic reactions, so there is no immunotherapy treatment available.
- Eczema and asthma: at present the evidence to support immunotherapy for eczema and asthma is limited, although some sufferers may be treated after seeing a specialist.
- Food allergy: e.g. peanut allergy: Research is still ongoing into developing preparations for food allergy desensitisation.
Is immunotherapy suitable for everyone?
Immunotherapy is a fairly time-consuming process, so you have to be committed to making it work. It is generally recommended that immunotherapy continues for 3-5 years.
If you are pregnant or planning on becoming pregnant, it is normally recommended that you wait until after the birth.
Children over the age of 5 can be suitable candidates for immunotherapy.
If you have other health conditions that you have concerns about, your specialist will be able to advise whether immunotherapy is suitable for you. Usually people with unstable asthma aren’t accepted for immunotherapy, as the risk from a severe reaction are higher.
How to access immunotherapy
Immunotherapy should always be carried out by a doctor trained in allergy, and in Australia is usually carried out in specialist allergy clinics or hospitals. You need a referral from your GP.
How much does immunotherapy cost?
At present only stinging insect immunotherapy treatments are covered on the PBS, however, this may change, so always check with your healthcare provider. Some private health fund policies cover some of the costs of allergen immunotherapy.
What’s involved in allergen immunotherapy?
First, your allergies will be assessed. This usually involves skin prick testing and /or blood tests. Your general health and fitness will also be assessed before any treatment starts. Remember to tell staff about ANY medicines or complementary therapies you take.
Immunotherapy for allergens is given by 2 methods:
- Immunotherapy injections; these are given under the skin. They are given weekly in the induction or build-up phase. After about 3 months, the time between injections is increased. In this maintenance phase, your regular GP may be able to give the injections. Normally, you will be asked to wait in the clinic for 30-45 minutes after the injection to ensure that a reaction doesn’t occur. Stinging insect allergy can only be treated by this method at present.
- Sublingual immunotherapy (SLIT). This involves tablets or drops from a spray being put under the tongue for a few minutes, then swallowed. SLIT can be done at home, so no need for doctor visits, except for the first dose.
Are there any side-effects?
Modern immunotherapy products are highly purified and so reactions are less common or less severe. However, the products used are now highly potent, compared with those of 10 years’ ago.
The chance of side-effects can be lessened by taking an oral non-sedating antihistamine before the injection, and avoiding sport, exercise, saunas and hot baths for a few hours either side of the injection. Potential side-effects, include:
- Localised itchy swelling at the site of the immunotherapy injection. This is common and can be treated with an ice pack and oral antihistamines, or if painful, with paracetamol.
- Large, local reaction. This is less common. Tell the clinic if you have a reaction, so they can adjust the next dose.
- Serious reactions, including hives, wheeze, hayfever symptoms, dizziness, drop in blood pressure, fainting/shock, flu symptoms a day or so later. These happen more commonly in the first few months of treatment, and usually happen within 30 minutes of the injection, which is why you have to remain in the clinic after each injection.
- Anaphylaxis or collapse. This is uncommon.
Side-effects can be mitigated by taking an oral antihistamine beforehand or temporarily reducing the dose. Side-effects may include:
- Salty, unpleasant taste.
- Itching or irritation inside the mouth.
- Stomach upset, pain or nausea (uncommon).
- Difficulty breathing or rashes (extremely rare).
How long does immunotherapy take to work?
Immunotherapy normally takes at least 3-6 months before symptoms improve, but doctors suggest giving it 9-12 months before judging.
2. AllergyUK. Immunotherapy. (Last updated June 2013). https://www.allergyuk.org/the-management-of-allergy/immunotherapy. (accessed Sept 2015).
3. Mayo Clinic. Allergy shots. Updated Feb 2015. http://www.mayoclinic.org/tests-procedures/allergy-shots/basics/definition/prc-20014493?p=1 (accessed Sept 2015).