Sperm allergy, or semen allergy, known in medical terms as seminal plasma hypersensitivity, is fairly rare, affecting between 20,000 and 40,000 Americans. The allergy is actually to proteins in the semen and not the sperm itself. It is unclear whether women who are allergic to semen are allergic to all semen or just to the semen of their particular partners at the time of diagnosis. It is less common, though possible, for men to be allergic to semen. Some men are even allergic to their own semen.
Symptoms of semen allergy include redness, swelling, itching and burning wherever the semen contacted your skin. Some people may suffer from hives, difficulty breathing or even anaphylaxis in reaction to semen they are allergic to. Symptoms usually start within the first 20 to 30 minutes of contact and may last for hours or days. The symptoms are sometimes mistaken for STDs or other conditions because semen allergy is so rare.
The best ways to treat a semen allergy are to minimize contact with semen (by using a condom, for example), or by being desensitized to the semen, which is something doctors can do by exposing you to tiny amounts of semen and slowly working their way up.
If you suspect that you may be allergic to your partner's semen, see a doctor, preferably an allergist, to be properly tested, diagnosed and treated. Don't worry about your semen allergy preventing you from the ability to get pregnant. If you have a severe sensitivity to semen, you may be able to use artificial insemination or in vitro fertilization to get pregnant. The sperm is washed before insemination, cleansing it of the semen proteins, which means you shouldn't have a reaction to it.