Allergy shots are the most commonly used and most effective form of allergy immunotherapy. Shots are effective in treating reactions to many allergens, including trees, grass, weeds, mold, house dust, dander, and insect stings.
An extract of a small amount of the allergen is injected into the skin of the arm. An injection may be given once a week (sometimes more often) for about seven months, after which injections can be administered every two weeks. Eventually, injections can be given every four weeks. The duration of therapy may be three to five years, sometimes longer.