Allergen Immunotherapy (AIT), or allergy shots, is a long-term treatment designed to address the underlying cause of allergic disease. AIT involves administering gradually increasing doses of specific allergens to induce immunological tolerance. This process shifts the immune response away from IgE antibodies, which trigger symptoms, toward protective IgG4 antibodies. Successful AIT modifies the disease, providing sustained relief that continues after treatment stops. Discontinuing this therapy requires careful consideration of the patient’s clinical progress and immune system modifications.
The Typical Treatment Timeline
Allergen immunotherapy is divided into two distinct phases, requiring a significant time commitment.
The initial period is the build-up phase, where the allergen extract concentration is gradually increased with each injection. This phase typically requires frequent visits, often once or twice per week, and generally lasts between three and six months. This slow escalation conditions the immune system to tolerate increasingly higher doses.
Once the maximum tolerated dose, known as the maintenance dose, is achieved, the patient transitions into the second phase. The maintenance phase involves administering a stable, high concentration of the allergen at less frequent intervals, usually every two to four weeks. This sustained exposure is necessary to lock in immune changes, particularly the induction of T regulatory cells that suppress allergic inflammation.
Medical guidelines suggest a minimum treatment length of three to five years once the full maintenance dose is reached. Stopping treatment before completing this minimum duration risks incomplete immune reprogramming, which can diminish the chances of permanent relief.
Criteria for Successful Cessation
The decision to end AIT is based on meeting specific clinical and immunological benchmarks, not solely on the passage of time. The most compelling evidence for successful treatment is sustained, significant symptom relief. An allergist typically looks for a period of one to two years during which the patient reports minimal or no allergy symptoms while on the maintenance dose.
A primary metric for success is the substantial reduction or complete elimination of the need for daily or seasonal allergy medications. Navigating peak allergy seasons with little to no pharmacological assistance indicates the immune system has been effectively retrained. The final decision to stop treatment is always a joint one, made after consultation with a board-certified allergist.
In some cases, the allergist may recommend repeat allergy testing, such as skin prick tests or specific IgE blood tests, to confirm the immune system’s shift. Retesting can provide objective evidence of reduced sensitivity to the target allergens. The collective achievement of sustained clinical improvement, minimal reliance on medications, and potentially favorable retesting results indicates that long-term tolerance has likely been met.
Risks of Stopping Treatment Prematurely
Stopping allergen immunotherapy before meeting the full clinical criteria risks incomplete immune tolerance. The immune system requires a specific period of exposure at the maintenance dose to establish lasting changes, such as blocking antibodies and regulatory T cells. Halting the shots too early interrupts this reprogramming process, leading to the loss of efficacy over time.
The most common consequence of premature cessation is symptom rebound, where allergic symptoms return with the same severity as before treatment began. This recurrence happens because the immune memory established during the shorter treatment window was not robust enough to withstand natural allergen exposure.
If symptoms return severely, the patient must restart the entire AIT process, beginning with the low-dose build-up phase. Restarting is necessary because the body’s level of tolerance is unknown after a prolonged break, and administering the previous high maintenance dose could trigger a severe systemic reaction. The commitment to the full, recommended course is a safeguard against having to repeat the multi-month, high-frequency build-up phase.
Monitoring After Treatment Ends
Once a patient and their allergist agree to stop AIT, the long-term prognosis is positive, but vigilance is necessary. Immune tolerance can persist for many years, but symptom recurrence, known as relapse, is possible. Relapse usually manifests as a gradual return of allergic symptoms, most likely within the first few years after stopping injections.
Patients should maintain annual follow-up appointments with their allergist to monitor for any subtle return of symptoms. Monitoring focuses on tracking symptom frequency, severity, and any increased need for allergy medications. The timeline for relapse varies widely among individuals, and some may maintain full relief indefinitely.
If a significant return of symptoms occurs, the allergist may recommend a short course of booster injections. If the initial treatment was successful for several years, a brief re-initiation of therapy may be sufficient to re-establish tolerance without requiring a full restart. Continuous communication with the healthcare provider is the most effective strategy for managing long-term health after AIT.