Prostate-specific antigen, the protein measured in the familiar PSA blood test for prostate cancer, has a second identity in allergy clinics. Researchers have identified it as an allergen behind semen allergy, and a similar protein made by male dogs may help explain why some women react to semen the very first time they are exposed.
The rare allergy drew fresh attention this summer. A July 29, 2026, case report in the Journal of Allergy and Clinical Immunology: Global described a 35-year-old woman in Japan whose repeated nighttime anaphylaxis was first blamed on a fish parasite before doctors traced it to her partner's semen. She went on to deliver a healthy baby after IVF.
