Stop Immunotherapy Early? What Happens Next | Curex

Quick Answer

Stopping immunotherapy before 3 years means losing most or all long-term benefit. The GRASS trial (Scadding 2017, JAMA) definitively showed that 2 years of treatment produces no sustained improvement after stopping. Three years of SLIT produced benefits lasting 7 years (Marogna 2010, n=78). Only 7% of SLIT patients complete the recommended 3-year minimum (Kiel 2013).

Quick Facts

Detail	Info
2-year course outcome	No lasting benefit — GRASS trial (Scadding 2017, JAMA; Renand 2018)
3-year course outcome	Benefits persisted 7 years (Marogna 2010, n=78)
4-year course outcome	Similar long-term benefit as 5 years — 8 years duration
SLIT completion rate	Only 7% finish 3 years (Kiel 2013)
Immune markers at 2yr post	67% maintained Treg, 83% persistent IgG4, 60% IgG4 above baseline (Suárez-Fueyo 2014/2018)
Cost of stopping at 1 year	~$1,200–2,400 with no lasting benefit; completing 3 years = $4,200–5,940 with 7+ year benefit (2026)

"I've Been Doing Allergy Drops for 8 Months — Can I Just Stop?"

You've been placing drops under your tongue every morning since last summer. Your symptoms improved — maybe 40%, maybe 60%, hard to quantify. Enough that you stopped reaching for Zyrtec every morning. Now you're looking at another 2+ years of monthly charges, daily doses, and the vague sense that you might already be "fixed."

The bottle sits on your bathroom counter next to your toothbrush. Some mornings you forget. Some weeks you forget several times. The subscription auto-renews and you wonder if the money would be better spent elsewhere.

Why Duration Determines Everything

Step 1 — Early improvement is temporary without immune consolidation. Symptom relief in the first 6–12 months comes from initial IgG4 blocking antibody production and early regulatory T cell (Treg) activity. But these immune changes haven't been "locked in" yet. At 2 years post-treatment, 67% maintained Tregs and 83% had persistent IgG4 — but only if they completed sufficient treatment duration first (Suárez-Fueyo 2014/2018).

Step 2 — Two years is not enough. The GRASS trial (Scadding 2017, JAMA) is the definitive study here. Patients who completed 2 years of sublingual immunotherapy showed no sustained benefit after stopping — their symptoms returned to pre-treatment levels. Renand 2018 confirmed this with immunological data. Two years feels like a long time, but biologically it isn't enough to produce lasting tolerance.

Step 3 — Three years crosses the durability threshold. The Marogna 15-year follow-up (n=78) showed that 3 years of SLIT produced benefits lasting 7 years after treatment ended. Four years produced 8 years. Five years also produced 8 years — nearly identical to 4. The 3-year mark appears to be where the immune system completes the remodeling needed for lasting change.

What To Do Next

Step 1 — Calculate where you actually are. Count your actual treatment months, not the months since you first ordered. Missed weeks add up. If you've been subscribed for 14 months but missed doses frequently, your effective treatment duration may be closer to 10 months.

Step 2 — If you're past 6 months with no improvement, reassess. About 20–30% of patients are non-responders regardless of treatment duration (Gotoh 2017). Continuing to year 3 when you've seen zero change by month 12 is unlikely to produce a different outcome. Talk to your provider about whether your formula needs adjustment or whether immunotherapy isn't the right approach for you.

Step 3 — If treatment is working, commit to the 3-year minimum. The financial math is stark: stopping at 1 year costs $1,200–2,400 with no lasting benefit. Completing 3 years costs $4,200–5,940 total but produces 7+ years of sustained relief. That's $600–850 per year of benefit vs money spent with nothing to show for it.

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When Stopping Early IS the Right Call

Not every early stop is a mistake. Pregnancy planning is a legitimate reason — conservative medical practice advises stopping immunotherapy during pregnancy. Starting immunosuppressive medications or managing severe acute illness may also require pausing or stopping. If you're experiencing persistent side effects that significantly impact quality of life despite dose adjustment, continued treatment may not be appropriate.

The uncomfortable truth: only 7% of SLIT patients complete 3 years (Kiel 2013). That means 93% of people who start allergy drops stop before reaching the minimum threshold for lasting benefit. The reasons range from cost to forgetfulness to feeling better and assuming they're done. Understanding this statistic doesn't change it, but knowing the stakes might help you decide which group you'll be in.

For children, the picture has an additional nuance: monosensitized children maintained benefits for approximately 7 years post-treatment, but polysensitized children saw benefit begin to wane from year 5 (Cui 2019).

Related Issues to Check

After immunotherapy: do allergies stay gone? — The long-term durability data that explains why 3 years is the minimum: 7 years of benefit vs zero from 2 years.
Allergy drops cost per month — If cost is driving your decision to stop early, comparing per-year cost of benefit ($600–850/year for 3-year completion) vs sunk cost of early dropout reframes the math.
Allergy drops not working — what to do — If you're considering stopping because drops aren't working, the issue might be formula adjustment, not treatment failure. Non-response assessment should happen at 6–12 months.

Frequently Asked Questions

Can I restart if I stopped early? One study (Marogna) reported that a "second course induced benefit more rapidly" — but this comes from a single study with no quantified data on how much faster. Restarting is possible, but you'll essentially be beginning the 3-year clock again.

What if I stopped at 2 years — did I waste my money? Partially. The GRASS trial showed 2 years doesn't produce lasting benefit after stopping. You likely experienced symptomatic relief during treatment, but those benefits will fade. The immune consolidation that happens in year 3 is what makes the difference.

Is stopping at month 6 worse than stopping at month 18? In terms of lasting benefit, both are insufficient. The GRASS trial showed even 2 full years didn't produce durable results. However, stopping at 18 months means you're closer to the 3-year threshold — continuing may be worth the remaining investment.

Why is the completion rate so low? Only 7% of SLIT patients complete 3 years (Kiel 2013). Contributors include cost, daily adherence burden, feeling better and assuming treatment is complete, and side effects. The drops-at-home model reduces office visit burden but doesn't eliminate the daily-dose challenge.

Does the 20–30% non-responder rate mean I might be wasting time? About 20–30% of patients do not respond to immunotherapy regardless of duration (Gotoh 2017). This is why the 6–12 month assessment matters — if you've seen meaningful improvement, you're likely a responder. If you've seen nothing, more time may not help.

Last reviewed: March 2026 · Sources verified against current data

Medically reviewed by Dr. Chet Tharpe, MD · March 2026

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