Could You Be Allergic to Sex?

Not tonight, dear, I'm allergic. This excuse sounds even less plausible than a headache but it can actually be a valid one: a small number of women actually are allergic to their partner's seminal fluid.

In fact, between 20,000 and 40,000 women in the United States may have this allergy, Dr. Jonathan Bernstein of the University of Cincinnati told Msnbc.com.  The causes for the allergy are still being studied, and so far it's unclear whether affected women will be allergic to all men or whether something has changed in her partner's semen to create the allergy.

Typically, the allergy starts in a patient who's been having sex with the same man over time. Following a period of abstinence, such as after pregnancy and childbirth, the allergy symptoms kick in, explains Dr. David Resnick, director of allergy at New York-Presbyterian Hospital, who treats about 15 women in New York City. The symptoms, which typically start within 30 minutes after unprotected intercourse, can range from hives, swollen eyes and diarrhea to trouble breathing and localized swelling in the vaginal area. Sometimes, according to Msnbc.com, the allergy, known as seminal plasma hypersensitivity, is mistaken for other vaginal conditions and even STDs.

Can You Self Diagnose?

It's actually fairly simple to make a diagnosis, according to Resnick. "If you have symptoms with unprotected intercourse, such as burning and swelling, and it does not happen with condoms, then the chances are that you may be allergic to your husband's semen," he says.

How It's Treated

There are actually two different treatments, Resnick explains. In one, the partner's semen is diluted and injected into the woman's vagina. Gradually, the dose is increased until the woman becomes desensitized and allergic symptoms vanish. In the other form of treatment, the woman receives these injections into the arm of her partner's semen.

"This second treatment is very costly so most people get the intervaginal treatment," Resnick explains. "It's faster and much less expensive."

How long does it last? For two or three days, Resnick explains, which means that after treatment the woman must have unprotected sex within 72 hours or else lose the sensitivity. The treatment must then be repeated.

Women who don't wish to undergo such treatment have another option: to use condoms during sex. "But there are many reasons why people don't want to use a condom," Resnick explains. "And the desire to get pregnant is one of them."