Allergy Immunotherapy Schedule: Every Modality's Timeline Compared

A complete allergy shot course typically involves 60 to 100 or more injections over 3 to 5 years. During the conventional buildup phase, you receive approximately 25–30 injections at weekly or twice-weekly intervals — that is about 6 months of regular visits. Once you reach maintenance, injection frequency drops to every 2–4 weeks for the remainder of the 3–5-year course. Year 1 maintenance adds roughly 10–15 injections, and each subsequent year adds about 12 more. Over a 3-year conventional course, most patients make approximately 57–60 total clinic visits. Cluster and rush protocols can reduce the total buildup injection count but do not change the maintenance phase duration or frequency.

During the maintenance phase of allergy shots, most patients receive injections every 2 to 4 weeks. According to a 2012 AAAAI member survey (Larenas-Linnemann et al.), 73% of US allergists schedule maintenance at every 4 weeks, with 12% using every 3 weeks. Some practices extend intervals to every 6 weeks for venom immunotherapy or very tolerant inhalant patients after the first year of stable maintenance. In the first year of maintenance, visits are typically closer together (every 3–4 weeks) and may space out as tolerance is established. Each visit still requires the full 30-minute post-injection observation period, so patients should budget approximately 45 minutes at the clinic plus travel time per visit.

The conventional allergy shot buildup phase takes approximately 3 to 6 months, or 8 to 28 weeks, per the AAAAI/ACAAI Practice Parameter (Cox et al., JACI 2011). At a standard weekly schedule, this means roughly 25–30 injections before reaching the maintenance dose. Cluster immunotherapy can compress the buildup into 4–8 weeks by giving 2–3 injections per visit on non-consecutive days — reaching maintenance with about 50% fewer visits than conventional, per Calabria (Ann Allergy Asthma Immunol, 2023). Rush immunotherapy compresses buildup even further, into just 1–3 days, but requires hospital or closely supervised clinic monitoring and premedication due to significantly higher systemic reaction risk.

SLIT and SCIT schedules differ fundamentally in clinic burden. Allergy shots require approximately 57–60 clinic visits over 3 years — each requiring travel, check-in, injection, and a mandatory 30-minute observation period. SLIT tablets and drops require only one or two supervised clinic visits for the entire course: the first dose must be taken under medical observation, then all subsequent daily doses are self-administered at home. This translates to roughly 27 hours of patient time over 3 years for SLIT versus an estimated 100+ hours for SCIT including travel. Both modalities require at least 3 years for durable post-treatment benefit, per EAACI 2018 guidelines. The scheduling gap is a major driver of patient preference — surveys consistently show 73% of patients prefer SLIT when given the choice.

Missing an allergy shot appointment requires a dose adjustment based on how long ago your last injection was. For buildup-phase gaps of 2–3 weeks, most protocols call for repeating the last dose; gaps of 3–4 weeks typically require stepping back by one dose; and gaps of 4–5 weeks typically require stepping back by two doses. A gap of 90 or more days during buildup typically requires restarting from the first diluted vial entirely. In the maintenance phase, a gap under 5 weeks usually means continuing at the same dose; 5–7 weeks prompts a 25% dose reduction; 7–11 weeks a 45% reduction; and a gap of 3 or more months generally requires restarting the full course. These schedules are based on expert consensus, not randomized trials (Larenas-Linnemann et al., 2020).

Yes, two accelerated schedules exist: cluster and rush immunotherapy. Cluster immunotherapy administers 2–3 progressively higher doses on a single visit day, with visits typically 1–2 times per week, reaching the maintenance dose in 4–8 weeks instead of 3–6 months. Rush immunotherapy compresses the entire buildup into 1–3 days, with injections given every 15–60 minutes under continuous medical supervision. Rush requires premedication with antihistamines, a leukotriene antagonist, and often a short oral corticosteroid course; it also carries a significantly higher systemic reaction rate. Both accelerated protocols are reserved for patients with stable, well-controlled asthma and no prior history of severe systemic reactions. Omalizumab pretreatment can further reduce reaction risk during rush protocols, per Casale et al. (JACI 2006).

This depends on the modality and allergen. Conventional SCIT (allergy shots) is administered year-round regardless of pollen season — the buildup and maintenance schedule continues throughout the year, though some allergists temporarily reduce doses during peak pollen season as a precaution. SLIT tablets for grass pollen (such as Grastek or Oralair) can be taken either year-round or pre-seasonally — FDA labeling recommends starting at least 4 months before pollen season and continuing through the season; some protocols extend to year-round for maximum disease modification. SLIT drops, including compounded multi-allergen preparations, are typically administered year-round for perennial allergens like dust mites and year-round or pre-/co-seasonally for pollens, depending on the prescribing allergist's protocol. EAACI 2018 guidelines require at least 3 years of total therapy for durable benefit, regardless of administration pattern.