Allergy Shot Immunotherapy: A Step-by-Step Walkthrough of One Visit

A typical allergy shot session follows a consistent sequence. First comes a review of any reactions since the last injection and whether a dose adjustment is needed — patients with asthma may have their peak flow checked. The prescribed dose is drawn from your personal vial, given as a subcutaneous injection into the posterior upper arm with a 26-27 gauge needle, and the site is checked briefly. Then comes a 30-minute observation window. With at-home SCIT through Curex, you self-inject at home with your first dose and every dose change supervised live over Zoom by the prescribing allergist, then self-observe for 30 minutes; in a clinic, a nurse performs these steps. Either way the session runs roughly 40-50 minutes.

Most patients describe allergy shots as a brief, mild pinch — less uncomfortable than a typical blood draw or vaccine. The needle used is a 26-27 gauge, half-inch length, which is one of the finest-gauge needles used in clinical medicine. The subcutaneous fat layer targeted by the injection is also less pain-sensitive than muscle (where vaccines go) or the dermis (where skin tests go). Some patients feel mild stinging or itching at the injection site in the minutes after injection — this is a normal local mast cell response, not damage. If a particular injection feels significantly more painful than usual, inform the nurse — it may indicate the angle placed the needle closer to the dermis.

Approximately 85% of systemic allergic reactions to allergy shots begin within 30 minutes of injection (Epstein et al., Ann Allergy Asthma Immunol 2011). The post-injection observation period exists specifically to catch and treat these reactions while trained staff and epinephrine are immediately available. Leaving before 30 minutes is complete means that if a reaction develops on the drive home, you would be without clinical support. This is not a precaution that can be safely skipped based on prior good tolerability — some reactions occur after a string of uneventful injections, particularly if the dose was recently increased or if the patient is in their peak allergy season.

Exercise should be avoided for at least 2 hours after receiving an allergy shot. Physical activity increases blood flow throughout the body, which accelerates allergen absorption from the subcutaneous injection site into systemic circulation — potentially triggering a reaction that would not have occurred with rest. The AAAAI/ACAAI Practice Parameter (Cox et al., JACI 2011) specifically cites post-injection vigorous exercise as a risk factor for systemic reactions. Light activity and normal daily tasks are generally fine after the 30-minute observation period is complete, but running, gym workouts, and competitive sports should wait at least 2 hours.

If symptoms develop in the hours after leaving the clinic — hives, widespread itching, runny nose, wheezing, or any systemic symptoms — contact your allergist's office immediately. For mild symptoms, an oral antihistamine is often the first step while you call for guidance. For any signs of throat tightening, difficulty breathing, dizziness, or severe wheezing, use an epinephrine auto-injector if prescribed and call 911 immediately. A phenomenon called biphasic anaphylaxis affects 5-20% of patients who have an initial anaphylactic reaction — a second reaction can occur 1-72 hours after the first. This is why any systemic reaction warrants medical evaluation even after initial recovery.

Both build-up and maintenance visits follow the same protocol — check-in, dose preparation, injection, and 30-minute observation — so the total time is similar: approximately 40-50 minutes. The practical difference is frequency: build-up visits occur 1-2 times per week (requiring roughly 25-30 visits over 3-6 months), while maintenance visits occur every 2-4 weeks. Over a 3-year course, the AAAAI/ACAAI protocol estimates approximately 57-65 total visits. At about 45 minutes per visit including travel, a typical 3-year SCIT course consumes an estimated 85-110 hours of patient time, most of which occurs during the intensive build-up phase.

Your allergy shot vial contains a liquid suspension of allergen extracts — proteins derived from the specific allergens your allergy testing identified as triggers. The extract is diluted in a saline solution, often with glycerin added as a stabilizer (preserving potency for 3-5 years). Your personal vials are prepared by your allergist's office from commercially manufactured allergen extract concentrates. The build-up series uses progressively less dilute vials, starting typically at 1:10,000 dilution of the maintenance concentrate and advancing through 1:1,000, 1:100, and 1:10 concentrations before reaching the full maintenance dose. Each vial is labeled with your name and the specific allergen concentrations.