Allergen immunotherapy (AIT) is an etiological treatment for IgE-mediated allergic diseases caused by sensitization to common allergens, such as dust mites and pollens. It involves the administration of gradually increasing dosages of allergen extract through repeated subcutaneous injections or sublingual routes, followed by a maintenance phase lasting at least 3 years. This therapeutic approach effectively alleviates patients’ allergic symptoms, improves their quality of life, and sustains its long-lasting efficacy even after discontinuation. The clinical trials and researches conducted in the past decades have unequivocally demonstrated that AIT possesses a distinctive mechanism for inducing tolerance, making it currently the sole targeted approach capable of altering the natural progression of allergic diseases. Therefore, its further promotion and reinforcement in clinical application is imperative.