If you’ve been living with asthma triggered by pollen, dust mites, or pet dander, you’ve probably tried inhalers, antihistamines, and nasal sprays. But what if there’s a way to change how your body reacts to these triggers-permanently? That’s where allergen immunotherapy comes in. Unlike medications that mask symptoms, immunotherapy trains your immune system to stop overreacting. And right now, two main options are available: allergy shots (subcutaneous immunotherapy) and SLIT tablets (sublingual immunotherapy). Both are backed by solid science, but they’re not the same. Choosing between them isn’t just about convenience-it’s about your lifestyle, your asthma severity, and what you’re willing to stick with for years.
How Allergen Immunotherapy Actually Works
Allergen immunotherapy isn’t new. It started in 1911 when a British doctor injected pollen extract into a patient with hay fever. Today, we know it works by slowly exposing your body to tiny, controlled amounts of the allergens that trigger your asthma. Over time, your immune system learns not to treat them like invaders. This isn’t just symptom relief-it’s disease modification. Studies show that after completing a 3- to 5-year course, many people see fewer asthma attacks, need less medication, and even stay symptom-free long after stopping treatment.
The key is specificity. Immunotherapy only works if you’re allergic to something measurable-like house dust mites, grass pollen, or cat dander. You need a skin test or blood test first. If your asthma is triggered by pollution, smoke, or exercise instead, this won’t help. And if your asthma is severe (GINA Step 4 or 5), you’re not a candidate yet. This treatment is for mild to moderate allergic asthma that’s not fully controlled by inhalers alone.
Allergy Shots: The Classic Approach
Allergy shots, or subcutaneous immunotherapy (SCIT), involve regular injections under the skin, usually in the upper arm. The process has two phases. First, a build-up phase: you get a shot once a week for 3 to 6 months. Each shot contains a slightly higher dose of the allergen. Then comes maintenance: you switch to monthly shots for 3 to 5 years. That’s about 50 visits total.
It’s not quick, and it’s not always convenient. But it’s effective. A 1999 study of 36 patients with dust mite allergies found that shots significantly improved both asthma and rhinitis symptoms. More recent real-world data from a 2024 study of over 14,000 patients showed that those on shots had fewer asthma flare-ups and needed fewer rescue inhalers over nine years. The reduction in inhaled corticosteroids was around 40%, which means less steroid exposure and lower long-term side effects.
But there’s a catch. Every shot carries a small risk of a systemic reaction-like hives, swelling, or trouble breathing. That’s why shots must be given in a clinic, and you have to wait 30 minutes after each one. If you travel often, work late shifts, or have trouble keeping appointments, this can be a dealbreaker.
SLIT Tablets: The Daily Alternative
Sublingual immunotherapy (SLIT) is simpler in theory: you place a tablet under your tongue and let it dissolve. No needles. No clinic visits after the first dose. The most common SLIT tablet for asthma is ACARIZAX, approved for house dust mite allergy. It’s taken daily, year-round, for at least three years.
Studies show SLIT tablets can reduce asthma symptoms just as well as shots-especially for people allergic to dust mites, which are a major trigger in places like Adelaide where humidity keeps mites thriving. One 2024 trial found patients using the full-dose SLIT tablet cut their daily inhaled corticosteroid use by 42%, compared to just 15% for those on placebo. That’s a huge difference in daily medication burden.
The biggest advantage? Convenience. After your first dose is given under medical supervision (to watch for rare reactions), you can take the tablet at home, at breakfast, before bed-any time that fits your routine. Adherence rates are higher: 75-80% of people stick with SLIT compared to 60-65% for shots. And side effects? Mostly mild: an itchy mouth or throat, which usually fades within a few weeks.
Comparing Shots and SLIT Tablets Side by Side
| Feature | Allergy Shots (SCIT) | SLIT Tablets |
|---|---|---|
| Administration | Injections in clinic | Tablet under tongue, daily at home |
| Frequency | Weekly (build-up), then monthly (maintenance) | Daily, all year |
| Total visits | ~50 over 3-5 years | 1-2 visits (initial + follow-up) |
| Time to start | 3-6 months to reach maintenance | Starts immediately after first dose |
| Best for allergens | Multiple: dust mites, pollen, mold, pet dander | Primarily dust mites (ACARIZAX), grass pollen (GRAZAX) |
| Systemic reaction risk | Higher (requires clinic monitoring) | Very low after first dose |
| Reduction in steroid use | Up to 40% | Up to 42% |
| Adherence rate | 60-65% | 75-80% |
| Cost over 3 years | Higher (clinic visits, staff time) | Lower (no visit costs after initial) |
SLIT tablets aren’t perfect. You can’t use them if you’re allergic to multiple allergens at once-you need one tablet for one allergen. If you’re allergic to both dust mites and grass pollen, shots might be better. Also, SLIT isn’t approved for all allergens in every country. In Australia, ACARIZAX is available but not widely prescribed yet. You’ll need to see an allergist who specializes in immunotherapy to get it.
Who Should Choose Which?
Let’s say you’re a parent with a child who has asthma triggered by dust mites. You work two jobs and can’t miss work for weekly appointments. SLIT tablets are the clear choice. You can give the tablet before school, no disruption.
Or you’re a 45-year-old who travels every month for work. You’re allergic to three things: grass, trees, and dust mites. Shots can cover all three in one series. SLIT tablets? You’d need three different products-and none are approved for tree pollen in Australia yet. Shots win here.
What if you’re scared of needles? SLIT is painless. What if you forget to take pills? Shots force you into regular contact with your doctor, which can help you stay on track. And if you’ve had a bad reaction to an inhaler in the past? Immunotherapy is a different kind of treatment-no steroids, no bronchodilators. Just your immune system being retrained.
What Happens After Treatment Ends?
This is the magic part. Most asthma medications only work while you’re taking them. Stop the inhaler? Symptoms come back. Stop SLIT or shots? Many people stay better. A 2024 study of nearly 3,000 patients found that even after stopping immunotherapy, they had 20% fewer lower respiratory infections needing antibiotics. That’s not just less asthma-it’s fewer colds, fewer bronchitis episodes, fewer trips to the doctor.
And for kids? The evidence is even stronger. Nine out of ten studies show that children with allergic rhinitis who get immunotherapy are far less likely to develop asthma later. That’s prevention, not just treatment. If you have a child with seasonal allergies, starting immunotherapy early could change their health trajectory.
Barriers and Real-World Challenges
It’s not all smooth sailing. First, cost. In Australia, SLIT tablets aren’t fully subsidized. You’ll pay out-of-pocket-around $150-$200 per month. Shots are partially covered under Medicare, but you still pay for each visit. Insurance coverage varies widely.
Second, access. Only a handful of allergists in Adelaide offer SLIT tablets. Most clinics still default to shots because they’ve been around longer. You might need to travel or wait months for an appointment.
Third, patience. Neither option works fast. You won’t feel better in a week. It takes 6-12 months to notice a difference. Most people quit before the 2-year mark because they don’t see immediate results. But if you stick with it, the payoff is real: fewer inhalers, fewer attacks, and a life less controlled by allergies.
The Bottom Line
Allergen immunotherapy is the only treatment for allergic asthma that can change the course of the disease. Shots and SLIT tablets both work. The difference is in how you live.
Choose shots if: you’re allergic to multiple allergens, you can commit to clinic visits, and you want the broadest allergen coverage.
Choose SLIT tablets if: you’re allergic to dust mites or grass pollen, you want to avoid needles, you value daily convenience, and you’re good at sticking to a routine.
Neither is right for everyone. But if your asthma is tied to allergies-and you’re tired of just managing symptoms-it’s time to consider a cure that doesn’t come in a puff.
Can SLIT tablets treat asthma caused by pet dander?
Currently, no SLIT tablets are approved in Australia for pet dander allergies. Only dust mite (ACARIZAX) and grass pollen (GRAZAX) tablets are available. For pet allergies, allergy shots are still the only form of immunotherapy that can include animal dander allergens in the mix.
How long until I feel better with allergy shots or SLIT?
Most people start noticing fewer symptoms after 6 to 12 months. The full benefit usually takes 2 to 3 years. Don’t expect instant relief. This is a long-term training program for your immune system, not a quick fix.
Are SLIT tablets safe for children?
Yes, SLIT tablets are approved for children as young as 5 years old in Australia for dust mite allergy. They’re often preferred for kids because they’re needle-free and easier to manage at home. Studies show they reduce asthma attacks and the need for rescue inhalers in children with allergic rhinitis.
Can I take SLIT tablets while using asthma inhalers?
Absolutely. SLIT tablets are designed to be used alongside asthma medications. In fact, many patients start SLIT while still using inhalers. Over time, as your immune system adjusts, your doctor may reduce your inhaler dose-sometimes by as much as 40%.
What if I miss a day of SLIT tablets?
Missing one day isn’t a big deal. Just take the next dose as scheduled. Don’t double up. If you miss more than 7 days in a row, contact your allergist. You might need to restart at a lower dose to avoid reactions. Consistency matters, but perfection isn’t required.
Is immunotherapy covered by Medicare in Australia?
Allergy shots are partially covered under Medicare if prescribed by a specialist. SLIT tablets are not currently subsidized, so you pay the full cost-around $150-$200 per month. Some private health insurers offer partial rebates for immunotherapy under extras cover. Always check with your provider.
Next Steps if You’re Considering Immunotherapy
Start with an allergy test. See an allergist who can do skin prick tests or specific IgE blood tests to confirm what’s triggering your asthma. If it’s dust mites, grass, or tree pollen, immunotherapy is worth exploring.
Ask your allergist: “Do you offer SLIT tablets? If not, why?” If they don’t, ask for a referral to a specialist who does. Bring up the 2024 Asperti study showing 42% steroid reduction-it’s now standard evidence in European guidelines and gaining traction here.
Track your symptoms for a month before starting. Note how often you use your rescue inhaler, how many nights you wake up coughing, how many days you miss work or school. After 12 months on immunotherapy, compare the numbers. You might be surprised how much better you feel.
