The concept behind immunotherapy (allergy shots or allergy tablets) is that the immune system can be desensitized to specific allergens that trigger allergy symptoms. The shots contain small amounts of substances that will sense the Immunodeficiency Disorder/Disease that you are allergic to. 

Allergy immunotherapy is a proven effective treatment for allergic rhinitis, allergic asthma, and stinging insect allergy when given over several years. It also may be effective in some individuals with atopic dermatitis (eczema) if they have allergies to airborne allergens. 

Immunotherapy can potentially lead to lasting remission of allergy symptoms, and it may play a preventive role in the development of asthma and new allergies.

Another form of allergy immunotherapy is called sublingual immunotherapy (SLIT) allergy tablets. Unlike shots, allergy tablets involve administering the allergens under the tongue on a daily basis. SLIT is available for grass pollen, short ragweed, and dust mites.

 You should consider allergy shots if:

• you are unable to avoid the things that you are allergic to
• your allergy symptoms are not reasonably well-controlled with medication
• you have asthma or frequent sinus infections