What Are Allergy Shots Made Of? Every Ingredient Explained

No — allergy shots do not contain live biological organisms. They contain purified allergen proteins that have been extracted, filtered, and processed from source materials such as pollen, dust mite cultures, or animal dander. The mite bodies used in dust mite extract are cultivated in controlled laboratory conditions, but the extraction process produces a protein solution, not live mites. Pollen extract contains pollen proteins but not viable pollen grains capable of germination. The allergen proteins are the immunologically relevant component — the specific structures that your immune system has been overreacting to — and they are present in pharmaceutical concentrations designed for safe gradual exposure.

Yes, in one important way: US allergen extracts are aqueous formulations with no adjuvants, while European depot preparations commonly include aluminum hydroxide or tyrosine as adjuvants. Adjuvants amplify the immune response, potentially allowing lower allergen doses to achieve similar efficacy or enabling faster build-up schedules. European depot preparations may require fewer total injections during build-up. However, adjuvanted preparations are not FDA-approved for use in the United States, where the clinical tradition and regulatory framework centers on aqueous allergen extracts. Both approaches share the same core principle of graduated allergen exposure to induce immune tolerance.

Human serum albumin (HSA) used in allergy shot formulations is derived from human blood plasma, not from eggs or egg whites. It is therefore not relevant to egg allergy. If you have concerns about blood-derived products for religious or other reasons, discuss with your allergist — some formulations may use alternative protein stabilizers. Egg allergy is not a contraindication to allergen immunotherapy. The relevant safety consideration for allergy shots is your current allergy sensitization profile and asthma control status. Always inform your allergist of all known allergies so they can formulate your extract appropriately and take appropriate precautions during your first injection visits.

Aqueous extracts use sterile saline as the primary diluent with phenol as the preservative, while glycerinated extracts use 50% glycerin as both the diluent base and preservative. Glycerinated extracts have a significantly longer shelf life — approximately one year at 4°C — compared to aqueous extracts, which degrade more rapidly, particularly at dilute concentrations. Most allergists use glycerinated extracts for the concentrated maintenance vials and aqueous extracts for the more dilute build-up vials. One trade-off is that glycerinated extracts can sting slightly more on injection due to the viscous glycerin solution. Both formulation types meet FDA standards and are widely used in clinical practice across the United States.

The 25–27 gauge needle used for allergy injections is deliberately thin — thinner than the needles used for most blood draws or intramuscular vaccinations. Most patients describe the sensation as a brief pinch lasting less than five seconds, comparable to a standard blood glucose finger stick. The injection goes into the subcutaneous fat layer of the posterior upper arm rather than into a vein or muscle, which also reduces discomfort. Injection site reactions — localized redness, swelling, and mild itching at the puncture site — occur in 30–80% of patients at some point during treatment but are considered a normal immune response rather than a sign of a problem. Applying ice to the injection site immediately after can reduce local swelling.

The allergen proteins in the shot are designed to trigger a controlled, low-level immune response — that is the mechanism of immunotherapy. Most patients experience minor local reactions at the injection site. Systemic reactions involving the whole body — hives, sneezing, nasal congestion, or in rare cases anaphylaxis — occur in approximately 0.1–0.2% of injections, which is why a 30-minute observation after each injection has long been standard. With Curex this is handled at home for eligible patients: a prescribed epinephrine auto-injector is confirmed on hand before the first dose, the first injection and every dose change are supervised live over Zoom by the prescribing allergist, and doses escalate gradually week by week — so if symptoms ever appear you use your epinephrine, call 911, and notify your care team. The non-allergen components (phenol, glycerin, human serum albumin, saline) are not allergenic at the concentrations used and are not responsible for allergic reactions to the shot.