Allergy shots, formally known as subcutaneous immunotherapy (SCIT), are a long-term treatment designed to decrease sensitivity to specific allergens like pollen, dust mites, or insect venom. This therapy involves injecting small, gradually increasing doses of the substances a person is allergic to, prompting the immune system to build tolerance. When administered under the guidance of a trained specialist following established medical protocols, allergy shots are considered a safe and effective treatment option for modifying the underlying allergic disease.
Expected Local and Systemic Reactions
Patients undergoing subcutaneous immunotherapy should anticipate certain mild reactions, which are common signs that the body is responding to the injected allergen. The most frequent occurrences are local reactions, manifesting solely at the injection site, typically within a few hours of the shot. These often include temporary redness, swelling, and itching in the upper arm. Local reactions are short-lived and manageable, sometimes with a cold compress or an over-the-counter antihistamine.
Less frequently, patients may experience mild systemic reactions, which involve symptoms beyond the injection site. These can include a runny nose, sneezing, mild generalized itching, or a small patch of hives. These minor reactions usually resolve quickly. Clinical data suggests that local reactions occur frequently, while mild systemic reactions are much rarer, sometimes occurring in about one per every one thousand injection visits. If these reactions are persistent or grow larger, the supervising clinician will adjust the dose to ensure the treatment remains tolerable.
Protocols for Anaphylaxis and Emergency Response
The most significant safety concern with allergy shots is the risk of anaphylaxis, a severe, life-threatening allergic reaction. To mitigate this low but serious risk, stringent safety protocols are mandatory for every injection. Shots must be administered in a healthcare setting equipped with trained personnel and emergency supplies. After receiving the injection, every patient is required to remain under observation for 30 minutes, as most severe reactions occur within this timeframe.
Trained medical staff are on-site and prepared to recognize and immediately treat anaphylaxis. The primary treatment for a severe systemic reaction is an injection of epinephrine (adrenaline). Epinephrine is administered intramuscularly, typically into the thigh, to quickly reverse the effects of the reaction, such as airway constriction and plummeting blood pressure. While life-threatening anaphylaxis is statistically rare—estimated to occur in about one per every 160,000 injections—the presence of trained responders and readily available epinephrine creates a robust safety net.
Who Should Not Receive Allergy Shots
The safety of immunotherapy depends on a patient’s underlying health status, and certain conditions are considered contraindications. Individuals with uncontrolled or severe asthma are generally not candidates for allergy shots. Their risk of experiencing a severe systemic reaction, particularly a life-threatening bronchospasm, is significantly higher because their airways are already compromised.
Certain cardiovascular conditions, such as heart disease or uncontrolled hypertension, may also preclude treatment. These conditions can make a severe allergic reaction more dangerous and the body less responsive to emergency treatment. Furthermore, patients taking certain medications, notably beta-blockers, are advised against immunotherapy. Beta-blockers interfere with the effectiveness of epinephrine, the necessary rescue medication for anaphylaxis. While treatment during pregnancy is often a relative contraindication, it is generally not initiated due to safety concerns.
Ensuring Safety During the Treatment Phase
Maintaining safety throughout the multi-year treatment phase relies on strict adherence to procedural safeguards. All allergy shots must be administered in a controlled clinical environment where medical staff can monitor the patient and intervene immediately if a reaction occurs. The treatment follows a gradual dose escalation schedule, known as the buildup phase, where the amount of allergen is slowly increased over time. This slow progression allows the immune system to adapt safely.
Patients must report any changes in their health, such as a fever, acute illness, or the start of a new medication, before every injection. An illness, particularly one affecting the respiratory system, can lower the reaction threshold, making a systemic reaction more likely. If a shot is missed or delayed, the dose may need to be lowered to prevent a reaction when the patient returns. These ongoing checks and adjustments ensure the continued safety of the treatment as the patient’s health and tolerance level evolve.