It is not uncommon for girlfriends and wives to make up excuses to not have sex with the men in their lives, but scientists say if she complains about being allergic to sperm, she may be telling the truth.

Medical experts say that some women suffer from a condition known as seminal plasma hypersensitivity, in which they have a bad reaction every time a man’s sperm enters their body.

“The body recognizes semen as a foreign protein just as it would recognize a peanut allergy or pollen,” said Dr. Andrew Goldstein, director of the Centers for Vulvovaginal Disorders in Washington D.C. and New York City. “So you have swelling, you have itching, you have inflammation of the nerve endings.”

Physicians say this condition affects 20,000 to 40,000 women in United States and is often misdiagnosed as a sexually transmitted disease. “If you have burning and swelling with unprotected intercourse, but not with condoms, you may be allergic to your husband’s semen,” say Dr. Jonathan Bernstein, an immunologist at the University of Cincinnati Medical Center.

Bernstein says that women experiencing allergic reactions to sperm may be doomed to a life of sex with condoms. He says that although there are some treatment options available, they are temporary.

Wow, now that's what we call a nut allergy.