In a very small number of cases, people have experienced allergic reactions when they touched semen. This is called human seminal plasma hypersensitivity. The symptoms (signs of the medical problem) can either be near the part of the body which touched the semen, or all over the body. They may include itching of the vagina, redness, swelling or blisters within 30 minutes of contact. They may also include itching and hives (large, red, itchy patches) all over the body, and even difficulty breathing.