Everything You Need to Know About Sublingual Immunotherapy

Sublingual immunotherapy is an allergy treatment that Dr Richard Baker has been using for over fifty years, and has been life changing for many patients. Many of our patients here at Allergy Testing Sydney, who want to improve their quality of life and reduce the impact of their allergies, ask about sublingual immunotherapy. This is a useful and convenient therapy for those who want to avoid the traditional, but more invasive, allergy injections (SCIT).

So today, let’s talk about sublingual allergy therapy—what it is, how it’s administered, and what the pros and cons can be for patients.

What is sublingual immunotherapy (SLIT)?

Sublingual immunotherapy for allergies works by exposing the patient to small, controlled doses of an allergen. Sublingual allergy treatment is a form of hyposensitisation. The idea behind sublingual immunotherapy is to introduce the allergen, which has been incorrectly identified by the body as harmful, in order to acclimatise the body. Over time, this reduces the impact of the allergens effect on generating an inflammatory or allergic type reaction.

How does sublingual immunotherapy work:

As the name suggests, the drops or tablets are placed under the tongue, or sublingually. This differs from previous treatments, which often involved injections with allergy shots.

These tablets or drops are placed under the tongue and dissolved. With the drops over time, the strength of the allergen is increased, with the aim to increase the patient’s tolerance to the allergen. The length of the treatment can depend on what you’re allergic to, and will be guided by the specific medical advice of your allergist.

As of June 2025, sublingual immunotherapy tablets and drops are not currently Medicare subsidised. 

Many allergy specialists around the world continue to offer customised SLIT drops (often referred to as “off-label”) based on the patients clinical history and test results.

Benefits of SLIT:

One of the biggest benefits of sublingual immunotherapy is that it can be done from the comfort of your home—no weekly clinic visits or invasive needles needed.

Other benefits include:

•       Safe for long-term use: SLIT has a strong safety profile, with fewer severe reactions compared to allergy shots.
•       Reduces reliance on medications: Many people find they need fewer antihistamines or puffers over time.
•       Long-term relief: When taken consistently, SLIT can lead to lasting symptom reduction—even after treatment ends.
•       High success rate: Clinical studies show SLIT can reduce allergy symptoms by 40–60% on average when taken consistently over 3+ years.
•       Suitable for children and adults: SLIT is often well-tolerated by children, making it a great option for young allergy sufferers who don’t cope well with needles.
•       May prevent the progression of allergic disease: Early treatment may reduce the risk of developing asthma or new allergies over time.

How long does sublingual immunotherapy take to work:

Most people begin to notice improvement in their symptoms within 3 to 6 months of starting treatment, especially during their usual allergy seasons. That said, for long-term changes in your immune response (and the best chance of sustained relief), SLIT is usually recommended to be taken for at least 3 years.

Comparing drops, tablets and shots:

Feature	Sublingual Drops	Sublingual Tablets	Allergy Shots (SCIT)
How it’s taken	Liquid drops under the tongue	Dissolvable tablet under the tongue	Injection into the arm
Administered At	Home	Home (after first supervised dose)	A clinic or doctor’s office
Frequency	Daily	Daily	Weekly to monthly
Customisable formula	Yes, can be tailored to individual allergens	No, standardised, usually 1–3 allergens per tablet	Yes, tailored to individual allergens
Allergens covered	Wide range (can mix pollens, dust, animal dander, moulds)	Limited, most commonly grass, dust mite, ragweed	Wide range, highly customisable
Duration of treatment	3–5 years	3–5 years	3–5 years
Effectiveness	Proven effective, especially for allergic rhinitis	Proven effective for specific allergens	Proven effective for most inhalant allergies
Onset of effect	Within months	Within months	Within months
Cost	May not be covered by insurance; varies by provider	Often covered by insurance	Often covered by insurance
Side effects	Mild (mouth itchiness, throat irritation)	Mild (similar to drops)	Local swelling, risk of systemic reactions (rare)
Safety profile	Low risk of serious reactions	Low risk of serious reactions	Requires monitoring due to risk of anaphylaxis
Convenience	Very convenient —no need for regular clinic visits	Convenient—first dose often given in clinic	Less convenient—requires regular visits
Best for	Patients wanting convenience and customisation	Patients with single/allergen-specific sensitivities	Patients with multiple severe allergies

 

Is sublingual immunotherapy safe?

Yes, the World Health Organisation has endorsed sublingual allergy immunotherapy as a safe alternative to allergy shots. Anaphylaxis is rare, and no fatalities have ever been reported from sublingual immunotherapy.

That being said, sublingual immunotherapy should be avoided if you have sores, cuts, or ulcers in your mouth, and should not be undertaken simultaneously with any dental procedures. This is because the small allergen dose may enter the bloodstream too quickly through an open wound, causing an adverse reaction.

Sublingual immunotherapy side effects:

Side effects are moderate, but some patients report feeling a localised reaction to the allergen. This might include mild swelling of the lips or cheeks. If this happens, tell your doctor, but your symptoms will likely improve over the coming weeks as you build up a resistance to the allergen.

About one in 10,000 doses of sublingual immunotherapy have reported:

•       Nausea and vomiting
•       Itching or redness of the eyes
•       Sneezing or congestion
•       Increased severity of asthma symptoms
•       Hives or swelling

While rare, you may also experience a reaction in the oesophagus, which can feel like heartburn, or as if it is difficult to swallow.

Sublingual immunotherapy cost:

The cost of SLIT therapy varies depending on your allergy, whether you are taking drops or tablets, and how long treatment will take. On average, SLIT tablets cost between $95 per month, and are taken daily for 3 to 5 years. SLIT drops at allergy testing cost only $30 per month.

On the other hand, SLIT drops, which are compounded by a compounding pharmacy under specialist direction, may have similar or slightly lower monthly costs, but are not listed on the Depending on your level of extras cover, rebates may be available through private health insurance.

Does Medicare cover sublingual immunotherapy?

Unfortunately, Medicare does not currently cover SLIT in Australia. This means the cost of sublingual immunotherapy allergy drops or tablets is generally an out-of-pocket expense.

SLIT tablets aren’t listed on the Pharmaceutical Benefits Scheme (PBS), and compounded allergy drops aren’t subsidised either. However, some private health insurance plans with extras cover may offer a partial rebate—so it’s worth checking with your provider.

Learn more from the allergy experts:

If you’re experiencing the impact of allergies and want to find out more, you might benefit from contacting us here at Allergy Testing Sydney. We can help you discover what’s causing your discomfort and direct you where to go next to find some relief.

Our clinic is led by medical director Dr Richard Stephen Baker. After graduating from the University of New South Wales Medical School in 1972, Dr Baker was trained in the United States by leading allergists. Today, Dr Baker is passionate about helping Sydney locals discover and better treat their allergies and has been at the forefront of treating sublingually during all his time as an allergist..  

 

Frequently asked questions:

What is the disadvantage of sublingual immunotherapy:

The lack of needles is a big draw for many, but there are a few downsides to sublingual immunotherapy to consider. This kind of treatment needs to be taken daily, often for several years, which can be a bit of a commitment. It’s also less effective for certain types of allergies compared to traditional allergy shots. And while side effects are usually mild, some people experience mouth or throat irritation, especially in the beginning.

 

Do allergy shots have long term side effects?

For most people, allergy shots are safe with minimal long-term side effects. The main risks are usually short-term, like redness or swelling at the injection site, or mild allergy-like symptoms after a shot. Serious reactions are rare, especially when the treatment is supervised.

What is sublingual immunotherapy food?

This refers to SLIT treatment designed for food allergies—for example, drops that help desensitise your immune system to common allergens like peanut, egg, or milk. This is still a developing area and not yet as widely available or proven as SLIT for things like pollen, dust mites or pet dander. If you or your child has a food allergy, it’s best to speak to an allergy specialist to see what options are available and safe.