Sperm allergy, sometimes called semen allergy or seminal plasma hypersensitivity, is a rare allergic reaction to proteins found in a man’s semen. It mostly affects women.

Some common symptoms of sperm allergy are redness, swelling, pain, itching, and a burning sensation in the vaginal area. Symptoms usually start about 10-30 minutes after contact with semen. They may not be confined to the vaginal area; they can occur in any area that has contact with semen, including the skin and the mouth. Symptoms can last for a few hours or a few days.

For some women, the symptoms are localized – they stay in one main area. But for others, the symptoms can affect their whole body. They may have hives, swelling, trouble breathing, or anaphylaxis, a life-threatening allergic reaction.

Sperm allergy may be discovered the first time a woman has sex, but sometimes it happens after a woman has had other sexual partners with no allergic reaction. Sperm allergy may also occur with one partner but not another. Or, it may happen suddenly with a longtime partner.

The condition is often misdiagnosed as vaginitis (inflammation of the vagina), a yeast infection, or a sexually-transmitted disease (STD) like herpes. One clue for diagnosis is condom use. If sperm allergy is present, the woman should not have any symptoms when she and her partner use a condom. The allergic reaction should only happen during unprotected sex.

Sperm allergy is frustrating for many couples and can be a strain on relationships. It can also complicate matters for couples who wish to conceive, since this usually can’t happen through unprotected intercourse. However, there are ways for a woman to become pregnant even with sperm allergy. The allergy does not affect her fertility and pregnancy can be achieved through artificial insemination or in vitro fertilization, after sperm is washed.

Women who suspect they are allergic to sperm should see their gynecologist or an allergist. Intradermal testing, in which a small amount of the partner’s semen is injected under the skin, can confirm whether there is an allergy or not.