Allergy immunotherapy is a long-term solution for people dealing with persistent allergies. However, unlike over-the-counter medications that provide quick and temporary relief, immunotherapy takes time to work. It aims to reduce the body’s allergic reaction over time, often requiring several years to deliver significant results.

But how long, exactly, does it take to see real, noticeable improvements with allergy immunotherapy? It all depends on you, and how your body responds to treatment, but for most, it takes two to three years to notice significant improvements. Here’s what you need to know about the timeline.

Understanding Allergy Immunotherapy

Allergy immunotherapy is a treatment that focuses on the underlying cause of allergies to provide long-term relief from symptoms. It works by gradually introducing the immune system to allergens and small, controlled doses. Over time, this exposure helps the immune system build tolerance, making it less reactive to these allergens.

There are two primary types of allergy immunotherapy: subcutaneous and sublingual. Subcutaneous immunotherapy, often shortened to SCIT, is typically administered in a clinical setting via an injection.

Sublingual allergy immunotherapy, often shortened to SLIT, involves allergen tablets or drops placed underneath the tongue, which can be taken at home. Both types are highly effective, with the bulk of patients experiencing reduced symptoms after completing treatment, which usually takes 3 to 5 years.

Phase 1: Initial Treatment and Building Tolerance (Weeks 1-6)

During the initial phase, also called the “build-up phase,” you’ll receive increasing doses of the allergen, either via an injection, tablets, or drops. This phase typically lasts from 3 to 6 months and is integral to building tolerance.

With subcutaneous immunotherapy, the first few weeks involve weekly shots at a clinic. The amount of the allergen in the dose will slowly increase, but the frequency of doses will decrease over time. For this type of immunotherapy, building up to a maintenance dose is vital, as this is the point at which the body starts to tolerate the allergen without severe reactions.

With sublingual immunotherapy, you’ll start by taking daily doses of the allergen underneath your tongue. The dose comes in the form of tablets or drops, so it’s easy to administer each dose at home without any help.

Expected Results: In this phase, most people don’t notice a significant improvement in symptoms. However, you may experience smile side effects like itching, redness, or slight swelling up the injection site or under the tongue. These reactions usually subside as your body adjusts.

Phase 2: Symptom Relief Begins (6-12 Months)

As your immune system begins to adjust and build a tolerance to the allergen, you may start experiencing noticeable relief from allergy symptoms. By this point, most people have reached a “maintenance dose”, where allergen exposure is high enough to impact the immune system without triggering a significant allergic reaction.

With subcutaneous immunotherapy, this happens at around the six-month mark. People often shift from weekly injections to monthly shots. Many patients report reduced symptoms such as less sneezing, congestion, and eye irritation, but complete relief might not be immediate.

With sublingual immunotherapy, daily doses continue at home as normal, but as with subcutaneous immunotherapy, patients should begin seeing symptom relief after about six months.

Expected Results: During this period, you should notice that your symptoms start to subside gradually, particularly for environmental allergies like pollen. You may find yourself relying less on over-the-counter medicine as immunotherapy starts to take effect. However, full relief may still be months to years away.

Phase 3: Significant Improvement (12-24 Months)

As you close in on the 2-year mark in your immunotherapy journey, you’ll probably begin to notice a significant reduction in your allergy symptoms. If you have severe allergies, this period may mark a dramatic change in your quality of life.

At this point, your immune system has built a significant tolerance, which helps prevent severe allergic reactions. For most people, that translates to fewer allergy symptoms and, in many cases, reduced or eliminated dependence on allergy medications

Expected Results: For many, this stage marks the beginning of lasting relief. Symptoms might not vanish entirely, but they often reduce significantly, allowing a marked improvement in lifestyle and overall well-being.

Phase 4: Maintenance and Long-Term Tolerance (3-5 Years)

The Final Phase of your immunotherapy journey introduces the long-term results you’ve been waiting for. After about three years of consistent treatment, the long-term benefits of allergy immunotherapy become clear. In this maintenance phase, your immune system has developed a lasting tolerance to allergens, making it less likely to react over time.

After reaching the three-year mark, many people using subcutaneous therapy can discontinue treatment while maintaining symptom relief for years. However, some allergists recommend continuing monthly shots for five years to increase the likelihood of long-term tolerance.

With sublingual immunotherapy, daily doses over three to five years generally foster long-term tolerance. It can take longer to achieve an allergen-specific tolerance with allergy drops, but it is just as effective as allergy shots.

Expected Results: At this point, many patients reach near-total symptom relief and can discontinue immunotherapy with lasting benefits. Of course, every person is different, so some may need to continue treatment to maintain their results, especially if new allergies develop or environmental exposure increases.

The Timeline of Allergy Immunotherapy: Closing Thoughts

Allergy immunotherapy is more of a journey than a quick fix. But with time and consistency, you can achieve significant, long-term benefits. While you may begin to notice slight improvements within the first year, it usually takes two or three years for the best results to appear. By the end of a full treatment course, most people enjoy a lasting tolerance to allergens, which often translates to a dramatically increased quality of life.

If you’re considering allergy immunotherapy, remember to chat with your doctor or allergist first. They can help you select the best treatment plan based on your needs and medical history.