Semen allergy, medically known as seminal plasma hypersensitivity (SPH), is a rare condition characterized by an allergic reaction to the proteins found in a man’s semen. Research has primarily focused on women, revealing that semen allergies are more prevalent among females, affecting as many as 40,000 in the United States. The reasons for this gender difference remain under investigation, emphasizing the need for further research to understand the impact of this condition on sexual relationships involving males.
Remarkably rare, it is even possible for a man to develop an allergy to his own semen, leading to a condition newly termed post-orgasmic illness syndrome. In some cases, women may experience symptoms with one partner but not with another, primarily due to the distinctive combination of proteins, fluids, and other components present in a man’s semen. Semen allergies can trigger local reactions within minutes or hours of exposure, often manifesting as contact dermatitis characterized by a red, itchy rash. These symptoms typically occur inside the vaginal canal, externally on the labia, or around the anus, and may include a rash, itching, hives, angioedema (swelling of the face, arms, or legs), and redness.