Can I be allergic to sperm?

Q: I met a guy on AMM about 11 months ago, we've been exclusive for 7 months and haven't been using condoms for the last 4-5 months. But for the last 5wks every time we have sex I'm left with this awful burning sensation which can last for days. It's not cystitis, it's different and it's definitely not some random sti, it's almost like an allergic reaction. I've been active sexually since I was 17 and never experienced this before. Any ideas?

You poor thing! Sex is supposed to burn you up in a good way, so it sucks to tell you that what you're experiencing isn't totally unheard of.

Semen allergies, or seminal plasma hypersensitivity, are pretty rare - but they can crop up seemingly at random at any given point in your life (and especially during times when your immune system is suppressed).

When you have a semen allergy, it's the proteins in the man's sperm that you're reacting to. This can lead to anything as mild as some redness, itching, and burning, or as severe as hives, trouble breathing, and even anaphylaxis. Most people notice symptoms in the areas that come in contact with the semen (the vagina, mouth, or hands), but in some cases, the whole body can feel affected. The symptoms can last for a couple of hours or a couple of days.

Even more baffling, it's possible to be allergic to all sperm, or just to some men's sperm in particular. And unfortunately, as you're experiencing, you can develop symptoms with a partner where previously no allergic reaction was occurring.

First things first, you need to visit your doctor about this issue. Fortunately, the medical community understands a little more about semen allergies these days. While you should always follow your doctor’s lead, you may want to ask about an allergy test.

There’s also something you can do at home to further investigate this issue. Try using a condom and see what happens. If your symptoms magically disappear when your partner is wearing a condom, there’s a good chance you're dealing with an allergic reaction. While this may not be the ideal solution, it can at least help you get frisky until your doctor helps you with treatment.

UPDATE: Surprisingly enough, just shortly after I answered this question I came across an interesting article that might shed some more light on this issue. A doctor in the UK says his research, which has yet to be published, indicates that up to 12 per cent of women may have a semen allergy - way more than previously thought. This higher figure may be due to the fact that some women are not reporting their symptoms or too embarrassed to seek treatment, or doctors misdiagnosing the issue. On top of that, the Daily Mail reports that  scientists at the University of Adelaide have found a connection between semen allergy and endometriosis. Yet another study suggests that previous allergies to dogs could be a factor in causing semen allergies in men. The article is definitely worth a read!