Causes
Typically, an allergic response is not triggered the first time the body encounters the semen allergen (protein in the semen that causes an allergic reaction). In fact, some people can be repeatedly exposed to the allergen before an allergy develops. The first time or several times after the body is exposed to the allergen, the immune system becomes sensitized. During this process, the body's white blood cells develop immunoglobulin E (IgE) antibodies to the semen allergens.