Once sensitized, the antibodies quickly detect and bind to the semen allergens the next time they enter the body. These antibodies also trigger the release of chemicals, including histamine, which cause allergic symptoms such as hives, inflammation, and itchy skin, as well as anaphylaxis. Anaphylaxis is a severe allergic reaction that affects many body parts. Symptoms of anaphylaxis include low blood pressure, difficultly breathing, shock, and loss of consciousness. Symptoms can vary from mild to severe and may be life threatening without immediate treatment.