What Is an Allergy Shot? Your First Appointment Step by Step

Most patients describe allergy shots as less painful than a blood draw. The 25–27 gauge needle is thinner than standard venipuncture needles, and the injection enters the subcutaneous fat layer of the upper arm rather than a vein or muscle. The actual injection takes under 5 seconds and produces a brief pinch sensation. Some patients feel mild stinging from the extract solution, which passes within seconds. Local reactions — redness, swelling, and mild itching at the injection site — are common (up to 80% of patients experience them at some point) and are normal immune responses, not signs of a problem. Applying ice to the site immediately after injection helps minimize swelling and discomfort.

The mandatory 30-minute observation period exists because approximately 98% of systemic allergic reactions to allergy shots occur within this window. Systemic reactions — hives, sneezing, nasal congestion, asthma symptoms, or in rare cases anaphylaxis — can occur even in patients who have tolerated previous injections without issue. Having trained medical staff immediately available during this period ensures that any reaction can be identified and treated promptly, typically with epinephrine and antihistamines. AAAAI and ACAAI practice parameters require this observation period to be conducted in the medical office with resuscitation equipment available — not in your car or the building lobby.

Allergy shots are given subcutaneously — into the fat layer under the skin — of the posterior upper arm, typically near the deltoid region. Arms are alternated between visits to allow the injection site to recover. The needle enters the subcutaneous adipose tissue at an approximately 45-degree angle using a skin-pinch technique to ensure the needle does not inadvertently enter the underlying muscle. Intramuscular injection would cause faster allergen absorption and increase systemic reaction risk, which is why proper injection technique is critical. The site is cleaned with alcohol before injection. Most patients experience minimal discomfort at the correctly targeted subcutaneous site.

Act immediately if you experience any of the following during the observation period: generalized hives, itching away from the injection site, runny nose or sneezing that started after the injection, throat tightness, wheezing, dizziness, or nausea. Do not wait to see if symptoms resolve on their own. With Curex at home, use your prescribed epinephrine auto-injector if a systemic reaction develops, call 911, and notify your care team — and on a Zoom-supervised first or changed dose your allergist directs treatment live. Local redness and swelling at the injection site are normal and do not require emergency intervention, but any symptom affecting areas away from the injection site warrants immediate attention. Epinephrine is the first-line treatment for a systemic reaction; antihistamines help milder symptoms. Most reactions are mild and resolve quickly with appropriate treatment.

Avoid vigorous exercise for at least 2 hours after your allergy shot injection. Physical activity increases blood flow and heart rate, which accelerates allergen absorption from the injection site into the systemic circulation. Faster absorption means higher peak allergen levels in the blood, increasing the risk of a delayed systemic reaction that occurs after you have left the office. Walking and light daily activity are generally fine. AAAAI practice parameters also advise avoiding hot showers or baths for 1 hour after injection, for the same reason — heat also increases local blood flow. Some allergists recommend avoiding exercise on injection days entirely rather than just for 2 hours, particularly during the build-up phase when doses are escalating.

Your first allergy shot appointment starts with the most dilute vial in your treatment series — typically labeled as the most concentrated dilution, such as 1:10,000 or 1:1,000 v/v concentration. This ultra-low dose is a safety precaution; even patients who have had extensive allergy testing can occasionally react to the first injection. Expect the full 30-minute observation period plus additional paperwork and orientation time — first appointments typically run 60–90 minutes. Your nurse will explain what reactions to watch for, provide your injection schedule, and give you post-visit instructions. Some practices also administer a small test dose and observe before giving the full initial dose on the first visit. Bring a book or phone for the wait, and wear a short-sleeve or loose-sleeve shirt for easy access to your upper arm.