How Long Do I Have to Take Allergy Shots? Your Personal Timeline Factors

Stopping at 2 years is possible but carries a higher relapse risk than completing 3 or more years. Naclerio et al. (JACI 1997) found that patients who discontinued at 2 years showed measurably higher rates of symptom return compared to those who completed 3 years. The EAACI guidelines (Roberts et al., Allergy 2018) explicitly state that a minimum of 3 years is required to achieve long-term efficacy that persists after stopping treatment, and that 2-year courses have insufficient durability data. If you need to stop at 2 years due to circumstances outside your control, your allergist may recommend a gradual tapering approach rather than immediate discontinuation, and you should discuss the likelihood of needing to restart in the future. A frank conversation with your allergist about your symptom status and IgG4 response at 24 months is the best guide to this decision.

Comorbid asthma typically extends the recommended allergy shot course toward the 4-5 year end of the standard range. Abramson et al. (Cochrane 2010) found that while SCIT meaningfully reduces asthma symptom scores, some asthma benefits require a full 5-year course to fully materialize. Additionally, patients with asthma require pre-injection pulmonary assessment — your allergist will check that your FEV1 remains above 70% of predicted before each injection. Asthma is also the dominant risk factor for severe systemic reactions during SCIT, making careful progression through build-up especially important. The practical implication: if asthma is part of your picture, plan for the full 5-year commitment when beginning immunotherapy, and work with both your allergist and pulmonologist to maintain good asthma control throughout.

Several factors are associated with a longer course or slower response. Being polysensitized — treated for three or more allergen groups — can extend the build-up phase and may require a longer maintenance period for full benefit, because cumulative allergen exposure across multiple targets takes more time to produce clinically meaningful tolerance. Severe baseline symptoms (classified as severe allergic rhinitis) predicted lower remission rates in a 304-patient HDM study (Lee et al., JACI 2018). Older age at treatment start is associated with slower IgG4 responses, though modern trials have shown meaningful benefit even in patients aged 60-75. Patients who miss injections frequently due to scheduling issues also extend their effective treatment duration because dose stepbacks add weeks to build-up. Finally, non-responders — patients showing no IgG4 rise by 12 months — may need dose adjustment or modality reevaluation rather than simply extending the course.

Most allergists use a combination of objective and subjective markers to decide when to stop. The AAAAI Practice Parameter (Cox et al., JACI 2011) defines the typical stopping criterion as 2 or more consecutive allergy seasons with minimal symptoms off rescue medications, after at least 3 years of maintenance. At the 12-month maintenance mark, your allergist may check your symptom-medication score trends, ask about rescue antihistamine use, and in some cases measure IgG4 blocking antibody levels, which peak at 12-18 months and serve as the best available biomarker of sustained immune tolerance. If your symptoms have significantly improved and you've reduced or eliminated rescue medication use, the discussion about stopping timing can begin. If you're still experiencing significant symptoms at 12 months of maintenance, your allergist may recommend adjusting your dose, allergen mix, or extending treatment rather than stopping.

Benefits after completing allergy shots can last anywhere from 3 to 12 years, depending on the allergen treated, the duration of your course, and individual immune factors. The landmark Durham et al. study (NEJM 1999) showed that symptom and medication scores remained low for at least 3 years after stopping a 3-4 year grass pollen SCIT course. The longest follow-up data comes from Eng et al. (Allergy 2006), who reported meaningful clinical benefit still present 12 years post-treatment in a grass pollen cohort. It's important to note that skin test reactivity may return toward baseline within several years of stopping, even while clinical benefits persist — suggesting that the immunologic and clinical durability mechanisms are partially independent. Patients who completed shorter courses (under 3 years) tend to have faster relapse than those who completed 3-5 years.

Children generally follow the same 3-5 year course recommendation as adults, but there are unique pediatric considerations. Research shows that SCIT started in childhood may provide additional benefits beyond symptom control: the PAT study (Jacobsen et al., Allergy 2007) found that 3 years of allergy shots in children with grass and birch pollen rhinitis reduced the likelihood of developing asthma by approximately half, with that protective effect persisting 7-10 years after stopping treatment. EAACI and AAAAI guidelines set the minimum age for SCIT at 5 years for practical rather than safety reasons — children must be able to communicate early reaction symptoms. Adolescents and young adults have the worst real-world adherence rates of any age group, so building a completion plan early in a child's treatment is especially important. Duration recommendations for children are not shorter than for adults, but the disease-prevention benefits of early treatment make the commitment particularly valuable.