It’s a story so strange that at first read it sounds like it could be an urban legend rather than a development in sexual health and allergy research. Several years ago, a 20 year old woman from the United Kingdom with a severe allergy to Brazil nuts reportedly had an allergic reaction after having sex with her partner who had consumed the nut just hours before their encounter. This was the first documented case of a woman having a sexually transmitted allergic reaction. In a world where more and more people are suffering from dangerous allergies, is this something the rest of us need to be concerned about?


You’re probably thinking, “there is no way the Brazil nut was transmitted through her partner’s semen, there had to have been some remains in his mouth, skin, or hair.” Fair enough, but the couple reports having taken every possible precaution before having sex. The man, having known that his partner was allergic, showered, washed his face, skin, teeth, and thoroughly rinsed his mouth before engaging in sex. The scientists who later studied the case stated that if the reaction were in fact from residue in his saliva or skin, she would have had the allergic reaction much faster than she did. She only started showing symptoms after they finished having sex.


The couple agreed to allow researchers to run a few tests on them. They took a sample of sperm from the man before he consumed Brazil nuts and another sample after. They then pricked the woman’s skin with both samples. The after sample caused an allergic reaction, while the before caused no reaction at all. The woman was advised to warn partners about her allergy and always keep her allergy medication handy after sexual encounters.


In order to understand this better a lot more research needs to be done on the subject. One case on it’s own isn’t enough evidence that allergens can be transmitted through semen. This particular case also doesn’t help us to understand if residue from all types of allergens could remain in the seminal fluid or only certain kinds. We need to know a lot more before suggesting any serious lifestyle changes, although for those with severe allergies it’s probably enough to make you ask your partner to take special precautions, just to be on the safe side.






Bansal, A.S., Chee, R., Nagendran, V., Warner, A. & Hayman, G. (2007). Dangerous Liaison: Sexually Transmitted Allergic Reaction to Brazil Nuts. J Investig Allergol Clin Immunol, 17, 189-191.

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Sexually transmitted allergic reaction: not your typical allergy by UrbanSculpt Staff Writer Meghan Stone, MSW, MEd is licensed under a Creative Commons Attribution 4.0 International License.
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