How Long Do You Need to Take Allergy Shots? Medical Recommendations

The minimum time recommended for meaningful disease modification from allergy shots is 3 years, per AAAAI and ACAAI practice parameters (Cox et al., JACI 2011). This includes the 3-6 month build-up phase plus a minimum of approximately 2.5 years of consistent monthly maintenance. The 3-year threshold is supported by Durham et al. (NEJM 1999), which showed lasting benefit post-discontinuation for patients completing at least 3 years. Stopping before this threshold — particularly before 2 years — typically results in symptom return within 12-18 months, suggesting that the disease modification achieved in under 2 years is insufficient to sustain lasting benefit after treatment stops.

Stopping allergy shots after only 1 year provides little lasting disease modification. Eng et al. (Clin Exp Allergy 2006) found that patients completing fewer than 2 years of SCIT showed significantly less disease modification at follow-up compared to 3-year completers. In practice, most patients who stop before 18-24 months experience symptom return within 12-18 months of discontinuation — similar to having received minimal treatment. The immune changes established in year one — rising IgG4, partial regulatory T-cell expansion — are real but not consolidated enough to sustain themselves long-term. If you need to stop before the 3-year mark, discuss with your allergist whether a restart plan is feasible once your schedule stabilizes.

Allergists use several clinical markers to determine when a patient can safely discontinue allergy shots. The primary criteria per Cox et al. (JACI 2011): at least 3 years of maintenance immunotherapy completed, a minimum of 12 consecutive months with well-controlled symptoms on maintenance, ideally 2 consecutive allergy seasons with minimal symptoms, and demonstrable improvement in skin test reactivity or specific IgE levels over the treatment course. Some allergists also assess whether the patient has been able to tolerate allergen exposures — like cat visits or high pollen days — that previously triggered significant symptoms. If all these criteria are met and the patient is not in a high-risk group (severe polysensitization, asthma), discontinuation is a reasonable decision.

Allergy shots are not permanently curative, but they produce long-lasting disease modification that outlasts the treatment itself. Durham et al. (NEJM 1999) showed benefits persisting at least 3 years after a 3-year course. Some patients maintain benefit for 10-12 years. The relapse rate after a complete 3-year course is approximately 15-25% within 3 years of stopping; after a 5-year course, the relapse rate falls to approximately 10-15% within 5 years. Patients who do relapse typically have milder symptoms than before treatment started, and many can successfully restart SCIT for a second course with an abbreviated build-up timeline, since partial immune tolerance is retained.

Five years of allergy shots produces more durable disease modification than 3 years. Multiple studies support this, including the landmark Durham et al. (NEJM 1999) study showing superior long-term outcomes for 3-year vs. 2-year completers, and extrapolation from the PAT study (Jacobsen et al., Allergy 2007) showing 7-year post-treatment benefit in children. Naclerio et al. (JACI 1997) reported approximately 15-25% relapse within 3 years of stopping a 3-year course, compared to 10-15% within 5 years of stopping a 5-year course. The additional 2 years of maintenance also improve cost-effectiveness — Hankin et al. (Ann Allergy 2013) found SCIT becomes cost-saving vs. ongoing medication at 5+ years — making 5-year treatment both clinically and economically superior for patients who can maintain the schedule.

Yes, patients who experience symptom relapse after stopping allergy shots can restart SCIT. The good news is that prior treatment is not wasted: patients who previously completed a significant portion of immunotherapy retain partial immune tolerance, which allows for an abbreviated build-up timeline compared to starting from zero. Your allergist will reassess your current skin test reactivity and specific IgE levels before designing a restart protocol. Patients who completed 3+ years often restart at an intermediate concentration rather than the lowest build-up dose. Re-treatment tends to be effective — retained partial tolerance means faster re-establishment of the maintenance dose and often a faster symptomatic response than the original course.

Some patients may benefit from treatment extending beyond 5 years. AAAAI guidelines recommend indefinite venom immunotherapy for patients who previously experienced anaphylaxis from stinging insects — Golden et al. (JACI 2017) found that stopping venom SCIT after 5 years in this population carries a higher relapse risk than in aeroallergen patients. For aeroallergen SCIT, patients with severe polysensitization, ongoing occupational allergen exposure (veterinarians, bakers), or poorly controlled asthma may benefit from extended treatment beyond 5 years on a case-by-case basis. For these patients, the ongoing benefit of continued monthly maintenance outweighs the inconvenience of continued treatment when symptom control would otherwise decline after discontinuation.