Anonymous on August 15, 2011

My girlfriend gets a rash after sex. Is she allergic to my ejaculate?

On a few occasions when I get some ejaculate on my girlfriend’s thighs or after intercourse, she gets a red rash like poison ivy. It doesn’t happen right away, but overnight and it goes away after a couple of days. Is it something in my diet? Medications? Or is she simply allergic to my ejaculate? The only allergy she knows she has is to sulfites...does my ejaculate contain them? We are both 24 years old, healthy, STD-free students, and we’ve been together four years.

answered by Ruthann M. Cunningham, MD on August 15, 2011

Thanks so much for asking these smart questions. They show that you care about the health of you and your partner.

Your girlfriend should visit her doctor to find out the cause of her rash. Ideally, she would make an appointment to see a health care provider when she still has the rash. In the meantime, I can offer you a few general answers to your questions...

Semen intolerance is rare, but it can happen. Semen is composed of proteins that can cause an allergic response in a small number of people. People who have this allergy are generally allergic to semen from all partners... not just one. Has your girlfriend experienced this rash with a previous partner? I would also expect vaginal symptoms (like itching or irritation) in addition to the rash on her thighs if she is allergic to semen. This is also something she can discuss with her doctor.

You may be able to test if your girlfriend is allergic to your semen by wearing a condom the next time you have sex. If she still develops a rash, she’s probably reacting to something other than your semen. Many people have allergies to other products commonly used during intercourse such as spermicide, lubricants or other creams and lotions.

A rash could also be a symptom of an STD. Just because you’ve been monogamous for the last four years doesn’t mean you’re both STD-free. And many STDs don’t show symptoms for a long time. When they do, a genital rash like the one you described is common. I encourage both of you to consider testing for STDs including HIV, herpes, chlamydia, gonorrhea, syphilis, and hepatitis B and C. Getting tested is the only way you can be sure that you are both STD-free.

After all, young people in your age group (15-24) are more likely to contract many common STDs than people in other age groups. Not to mention, complications from untreated STDs can include everything from infertility to heart disease, certain cancers and other abnormalities.

I would also encourage your girlfriend to see her doctor for a definite diagnosis of her symptoms.

Thanks again for getting in touch.

Related info:

Ruthann M. Cunningham, MD

Dr. Cunningham is a member of the Analyte Physicans Group. She's also a member of the American College of Emergency Physicians, practicing at both Northwestern Lake Forest Hospital in Illinois and at Wheaton Franciscan All Saints Medical Center in Wisconsin. An ER physician since 2000, she regularly treats patients with STDs. Dr. Cunningham was educated at Wayne State University School of Medicine and completed her Emergency Medicine residency at Cook County Hospital in Chicago, IL.

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