When your asthma won’t improve no matter how many inhalers you use, it’s time to ask: is this really asthma, or is it allergies in disguise? For millions of people with allergic asthma, the root cause isn’t just airway inflammation-it’s an overreactive immune system responding to dust mites, pollen, or pet dander. That’s where allergen immunotherapy comes in. Unlike inhalers that mask symptoms, immunotherapy rewires your immune system to stop overreacting. And for the first time in decades, there’s a real choice: allergy shots or SLIT tablets.
What Is Allergen Immunotherapy, Really?
Allergen immunotherapy (AIT) is the only treatment for allergic asthma that changes the disease itself. It doesn’t just calm symptoms-it teaches your body to ignore the allergens that trigger your asthma. Think of it like a vaccine, but instead of fighting viruses, you’re training your immune system to stop seeing harmless things like dust mites as enemies.
It’s not new. Back in 1911, Dr. Leonard Noon gave the first allergy shot using pollen extract. Today, we have two proven methods: subcutaneous immunotherapy (SCIT), or allergy shots, and sublingual immunotherapy (SLIT), which uses tablets or drops placed under the tongue. Both work over time-usually 3 to 5 years-to reduce your sensitivity. And unlike daily medications, the benefits often last long after you stop treatment.
Studies show people on AIT are up to 40% less likely to need asthma medications like corticosteroids. One 2024 study found that patients using SLIT tablets reduced their inhaled steroid dose by 42% on average. That’s not just symptom relief-it’s a real reduction in drug burden, side effects, and long-term health risks.
Allergy Shots: The Classic Approach
Allergy shots mean regular trips to the doctor’s office. You get a small injection under the skin, usually in the arm. The process has two phases: build-up and maintenance.
During the build-up phase-which lasts 3 to 6 months-you get shots once a week. Each dose slowly increases until you reach the effective level. Then you switch to monthly maintenance shots for the next 3 to 5 years. That’s about 50 visits total. It’s time-consuming, but it works.
SCIT is especially effective for people allergic to multiple allergens. One shot can contain extracts from several triggers-dust mites, cat dander, ragweed, grass-all mixed together. That flexibility makes it a go-to for complex cases.
But there are downsides. You can’t skip a visit without losing momentum. And while most reactions are mild-redness or swelling at the injection site-there’s a small risk of a serious allergic reaction. That’s why you have to wait 30 minutes after each shot. It’s a safety rule, not a suggestion.
Adherence is the biggest hurdle. Studies show only about 60-65% of patients stick with it for the full course. Life gets busy. Work schedules clash. Kids miss school. The commitment is real.
SLIT Tablets: The Daily Alternative
SLIT tablets are what most people imagine when they think of modern allergy treatment. You take one tablet daily, placing it under your tongue for two minutes before swallowing. No needles. No clinic visits after the first dose.
The first dose is always given under medical supervision because of the rare risk of a systemic reaction-like swelling, trouble breathing, or low blood pressure. But after that, you can take it at home, at work, even while traveling. That convenience drives higher adherence. In fact, studies show 75-80% of patients stick with SLIT for the full treatment period.
The most common side effect? Mild itching or tingling in the mouth. It usually fades after a few weeks. Some people report a strange taste or throat irritation, but these rarely stop treatment.
SLIT tablets are standardized. That means each tablet delivers a precise, consistent dose. For dust mite allergies, the standard is 6 SQ-HDM units. The brand ACARIZAX is approved in Europe and used in many U.S. clinics, though the FDA has approved fewer SLIT options than Europe.
For people with dust mite-triggered asthma, SLIT isn’t just convenient-it’s effective. A 2024 real-world study of over 2,600 patients showed a 20% drop in lower respiratory infections needing antibiotics after three years of SLIT. That’s fewer sick days, fewer ER visits, and less reliance on rescue inhalers.
Which One Works Better for Asthma?
Early studies in the late 1990s suggested allergy shots were better for asthma control. One small 1999 trial found SLIT helped rhinitis but didn’t improve asthma scores. That study shaped guidelines for years.
But times have changed. Newer, larger studies tell a different story. A 2024 analysis of over 14,000 patients found that both SCIT and SLIT led to major, lasting reductions in asthma and rhinitis medication use. The difference? SLIT users were more likely to stick with treatment, which means they got the full benefit.
For dust mite allergies-the most common trigger for year-round asthma-SLIT tablets are now considered equally effective as shots. In fact, they may be better for some people because they’re easier to take consistently.
But here’s the catch: neither works if your asthma is severe (GINA Step 4 or 5) or if your triggers aren’t allergic. If your asthma flares from cold air, exercise, or stress without an allergic component, immunotherapy won’t help. You need to know your triggers first.
Who Should Choose Shots? Who Should Choose Tablets?
Let’s cut through the noise. Here’s who wins with each option:
- Choose allergy shots if: You’re allergic to multiple allergens (like pollen, mold, and pet dander), you can commit to weekly visits for months, and you want the broadest possible allergen coverage in one treatment. You’re also more comfortable with medical supervision.
- Choose SLIT tablets if: Your asthma is triggered mainly by dust mites or grass pollen, you want to avoid needles, you travel often, or you’ve struggled to stick with doctor visits. You’re willing to take a pill every day, even if it’s just for a few minutes.
Parents of kids with allergic asthma should pay attention. Evidence shows AIT can actually prevent asthma from developing in children with allergic rhinitis. Nine out of ten studies confirm this. That’s huge. If your child has persistent sneezing and runny nose from allergies, starting immunotherapy early might stop asthma before it starts.
Cost, Access, and Real-World Barriers
Cost varies wildly. In the U.S., allergy shots are often covered by insurance, but copays add up over 50+ visits. SLIT tablets are pricier per month, but fewer visits mean lower overall costs for some. In Europe, SLIT is more widely covered and prescribed. In the U.S., only 10-15% of allergists routinely offer it.
Access is a problem. You need an allergist who knows how to prescribe and monitor AIT. Not every clinic does. And if you live in a rural area, finding one might mean driving hours.
Insurance approval can be tricky. Some plans require proof that standard asthma meds failed before covering AIT. Others won’t cover SLIT unless you have a specific diagnosis like dust mite allergy. Check your plan before starting.
What Happens After Treatment Ends?
This is the magic part. Unlike asthma inhalers, which only work while you take them, immunotherapy changes your body’s long-term response. After 3-5 years, you stop. And the benefits? They stick around.
Studies show people who completed AIT had fewer asthma attacks for up to 9 years after stopping treatment. Medication use stayed lower. Emergency visits dropped. And in kids, the risk of developing asthma stayed down for years after treating their allergies.
That’s why experts call it the only disease-modifying treatment for allergic asthma. It doesn’t just manage-it transforms.
What If It Doesn’t Work?
Immunotherapy isn’t a magic bullet. About 10-20% of people don’t respond well. Reasons include:
- Incorrect allergen identification (you’re allergic to something the test missed)
- Non-allergic asthma triggers
- Severe asthma (GINA Step 4 or 5)
- Poor adherence (missing doses or shots)
If you’ve tried both methods and still struggle, your allergist may recommend biologics-newer drugs like omalizumab that target specific immune pathways. But those are expensive and require ongoing injections. Immunotherapy remains the first-line disease-modifying option.
Getting Started
If you think you might benefit from immunotherapy, here’s how to begin:
- Get tested. Skin prick or blood tests (specific IgE) will identify your triggers. Don’t skip this. If you’re allergic to ragweed but your asthma is triggered by dust mites, shots for ragweed won’t help.
- Confirm your asthma is allergic. Your doctor will look at your history: seasonal flares? Symptoms near pets or dusty rooms? Positive allergy tests?
- Discuss options with an allergist. Ask: "Do you offer SLIT tablets? Which allergens do you treat with them?" If they don’t offer SLIT, ask why.
- Consider your lifestyle. Can you commit to weekly visits? Do you travel often? Are you okay with daily pills?
- Check insurance coverage. Call your provider and ask about AIT coverage-shots and tablets-are they both included?
Don’t wait until your asthma is out of control. If you’ve been relying on rescue inhalers more than twice a week, it’s time to think beyond symptom management. Allergen immunotherapy might be the step you’ve been missing.
Are allergy shots safe for children?
Yes, allergy shots are safe for children as young as 5 years old, and SLIT tablets are approved for kids 12 and up. Both are effective in reducing asthma symptoms and may even prevent asthma from developing in children with allergic rhinitis. Pediatric allergists often recommend starting early, especially if symptoms are worsening or medications aren’t enough.
Can I take SLIT tablets if I have seasonal allergies?
Yes, SLIT tablets work for both seasonal and year-round allergies. The most common tablets target grass pollen (GRAZAX) and dust mites (ACARIZAX). If your asthma flares in spring due to grass pollen, SLIT can reduce those attacks. For dust mites, which are present year-round, SLIT helps control chronic symptoms. Your allergist will match the tablet to your specific trigger.
How long before I feel better with immunotherapy?
Most people notice improvements within 6 to 12 months. Some feel better sooner, especially with SLIT. But the full benefit-reduced medication use, fewer attacks, lasting protection-takes 3 to 5 years. Don’t expect instant results. This is a long-term investment in your immune system.
Do SLIT tablets work as well as shots for asthma?
For dust mite-triggered asthma, yes. Recent studies show SLIT reduces asthma exacerbations and corticosteroid use just as effectively as shots. For multiple allergens, shots may still have a slight edge because they can combine triggers in one injection. But for single triggers like dust mites or grass, SLIT is equally effective-with better adherence and fewer side effects.
What if I miss a dose of SLIT?
If you miss one day, take it the next day. Don’t double up. If you miss more than three days in a row, contact your allergist. You may need to restart at a lower dose to avoid a reaction. Consistency matters, but occasional slips won’t ruin your progress-just get back on track.
Can I switch from shots to tablets?
Yes, but not automatically. If you’re on shots and want to switch to SLIT, your allergist will need to restart the treatment with the tablet. You can’t carry over your dose from shots. It’s a new course. But many patients switch for convenience-especially if they’re traveling more or find clinic visits hard to manage.
