We often encounter patients with “allergies” asking for “desensitization”, as if “desensitization” can cure allergies. Today we’ll find out what “desensitization” is all about. What is “desensitization”? “Desensitization” is a common term among the general public, but from a professional point of view it is called “allergen-specific immunotherapy”. This treatment has been around for over 100 years, and the early idea of desensitization came from vaccination against infectious diseases, mainly to relieve the symptoms of hay fever (allergic rhinitis) patients. Over the past 100 years, the route of desensitization has also gone through different stages such as transnasal mucosal desensitization, transbronchial desensitization, oral desensitization and subcutaneous desensitization. Due to the higher risk of inducing systemic allergic reactions with subcutaneous desensitization, sublingual desensitization has been accepted by more doctors and patients in the last 20 years or so. The purpose of desensitization is to expose the allergic patient to the appropriate allergen in small doses and then gradually increase the dose and maintain it for a longer period of time (usually more than 2 years), eventually allowing the body to develop tolerance to the allergen or to induce the body to produce protective antibodies and immune cells that can counteract the allergic reaction. At this point, the patient will not experience significant allergic symptoms when exposed to the environmental allergen again. Can any allergen be desensitized? The main allergens that can be desensitized at this time are pollen and dust mites. Many substances that we are exposed to in the environment can cause allergic reactions, such as food, food additives, medications, metals, fragrances and preservatives in skin care products, etc., but none of these allergens can be desensitized. Can all allergic diseases be desensitized? The causes of allergic diseases are diverse, and the mechanisms of allergic reactions induced by different allergens are not identical. Only diseases whose pathogenesis is related to IgE can be treated with allergen-specific immunotherapy. The current approved indications for desensitization therapy are: allergic rhinitis, allergic asthma and bee venom allergy. These diseases are characterized by allergic symptoms within a short period of time after exposure to allergens, such as dust mite allergy patients will soon develop itchy nose, runny nose, sneezing or aggravated asthma after exposure to large amounts of dust mite allergens; bee venom allergy patients will develop shortness of breath, panic and even acute anaphylaxis after being stung by a bee within a short period of time. Some common “allergic” skin diseases, such as contact dermatitis, most dermatitis eczema, food and drug allergies and urticaria, are not completely related to IgE and cannot be treated by desensitization. When allergens are identified, avoiding exposure is the most important prevention method. For example, for hair dye allergy or facial cosmetic allergy, after the substance causing the allergy is identified through patch test, avoiding further contact with the hair dye or the cosmetic causing the allergy can prevent re-allergy. Some food and drug-induced skin allergies can also be prevented from recurring by avoiding the food and drug that caused the allergy, without the need for desensitization treatment. Can people with atopic dermatitis undergo desensitization? Some patients with atopic dermatitis have allergic reactions to substances in the environment, and dust mite allergy is the most common allergen detected during allergen testing. Can these patients undergo dust mite desensitization? Desensitization is evaluated in the 2014 US and 2015 European guidelines for the treatment of atopic dermatitis/eczema: 1. Desensitization is not recommended as routine treatment for patients with atopic dermatitis with dust mite allergy; 2. Based on the results of the limited clinical studies available, some patients with atopic dermatitis with dust mite allergy may respond well to desensitization and may attempt desensitization; 3. 3. how to screen patients who may be effective for dust mite desensitization therapy: if the patient has a more persistent rash, poor efficacy of conventional topical medications and skin care, very high blood dust mite IgE levels, positive skin prick test, aggravation of eczema when exposed to more dust mites through daily observation or positive dust mite allergen patch test. These patients may try dust mite desensitization. Therefore, patients with atopic dermatitis/eczema who are found to be allergic to dust mites should not be blindly treated with dust mite desensitization, but should be judged in the context of their clinical presentation and medical history. Even if there is a high suspicion that exacerbation of eczema is related to dust mite allergy, desensitization may be attempted, but it should not be misunderstood that desensitization is the only way to eradicate eczema. Anti-inflammatory drug therapy and moisturizing skin care for the skin are currently the most effective ways to control eczema.