Semen allergy - also known as seminal plasma hypersensitivity - generally affects women more than men (but men can also be allergic to their own semen) and is caused by antibodies in women's bodies recognizing semen as harmful, and going into an overdrive response.
Women may experience inflammation, an itchy sensation and swelling of the genitals shortly after contact with semen. Luckily, reactions tend be localized, and I'm not aware of any cases where women have gone into anaphylactic shock, although theoretically, this could happen.
Generally, it's considered quite unusual, although one study has suggested the incidence could be as high as 12 percent.
For women who experience semen allergy, I usually recommend they should use condoms and or dont swallow. For men who love bareback action well you will just have to pull out and empty into a copy of the Radio Times left open on a double page spread of Nick Knowles.
However, it can be tricky when women want to get pregnant. They may experience discomfort until conception. In severe cases, assisted reproductive technology has to be used.
If you google it you can see the nasty rash it can cause
https://www.dailymail.co.uk/health/a...eeds-know.html
who knew?