A rare medical case from Lithuania has shocked doctors around the world: a 29-year-old woman has been diagnosed with a semen allergy, which is preventing her from becoming pregnant.
The woman had been trying to conceive naturally for a long time without success. After multiple failed attempts, she opted for in vitro fertilization (IVF) twice—but both attempts failed. Initial medical evaluations revealed no clear cause, prompting specialists to conduct an allergy test. The result was surprising: she was allergic to a specific protein found in semen.
What Is Human Seminal Plasma Allergy?
The condition is medically known as Human Seminal Plasma Allergy (HSPA). It’s an extremely rare immune response, with only around 80 documented cases worldwide to date. Women with this allergy react negatively to proteins in seminal fluid, often mistaking them as harmful substances.
In this case, the woman already had a history of allergies to dust, mold, cats, and dogs. She visited an allergy specialist after repeatedly failing to conceive. Blood tests revealed elevated levels of eosinophils—a type of white blood cell associated with allergic reactions.
Further testing showed an intense reaction to Can f 5, a protein found in dog dander. Interestingly, this protein is structurally similar to a protein in seminal fluid. This similarity led doctors to test her for a semen allergy—confirming the rare diagnosis.
Symptoms and Impact on Fertility
The woman reported symptoms such as nasal congestion, sneezing, and a burning sensation in her genitals after unprotected intercourse. However, she was unaware these reactions were linked to a semen allergy.
Doctors explain that in cases of HSPA, the female body treats semen proteins as foreign invaders, triggering an immune response. This immune activity can interfere with sperm function, making natural conception nearly impossible.
Experts Warn the Condition May Be Underreported
Though rare, health experts believe the actual number of cases may be higher. Due to social stigma, embarrassment, or lack of awareness, many women may not report such symptoms or seek medical help.
Doctors advise that couples facing unexplained infertility should consider consulting allergy specialists, especially if the woman experiences discomfort after intercourse.
