Woman suffers deadly nut allergy after having sex with partner in shocking first of its kind case

A man went to every length not to pass traces of nuts to his girlfriend before having sex, but as it so happened he was just one nut from doing so.

Having seemingly taken every precaution, with the boyfriend having washed himself, his mouth and even his fingernails, a 20-year-old woman - with a deadly allergy to a specific type of nut - thought no harm would come with them sleeping together.

The 20-year-old woman couldn't figure out why she was in pain (Getty Stock Image)

Unfortunately, she was wrong but a study was launched on the back of their misfortunes.

"The patient's partner was aware of the patient's very significant nut allergy and had bathed, brushed his teeth and cleaned his nails immediately before intercourse as he had consumed mixed nuts roughly two to three hours earlier. These had included between 4 to 5 Brazil nuts," researchers in their 2007 study, published in the Journal of Investigational Allergology and Clinical Immunology, said.

"The patient had been diagnosed with Brazil nut allergy 2 years earlier as a result of several episodes of urticaria and angioedema after consuming foods containing nuts," doctors stated.

Urticaria, also known as hives, is a skin condition that causes red, itchy bumps to appear while angioedema refers to the swelling of the skin.

The researchers continued: "The cause of the patient's post-coital reaction was initially unclear. However, the history suggested a possible Brazil nut reaction with the Brazil nut proteins being secreted into her partner's semen."

The woman had a deadly allergy to nuts (Getty Stock Image)

Yes, I'm sure you saw where this was going... if you're reading this I'm sure you've already had the birds and the bees conversation so you don't need me to spell it out.

"A 20-year-old woman in a stable relationship developed widespread urticaria and angioedema shortly after vaginal intercourse with her partner. Condoms were not used as the patient was taking the contraceptive pill," explained authors AS Bansal, R Chee, V Nagendran, A Warner, G Hayman, of the Department of Immunology at St Helier Hospital, in Surrey, England.

After having sex the young woman 'suffered significant itching and swelling of her vagina and vulva and felt faint even when sitting', although there was no obvious sign that she was going into anaphylactic shock so she took an antihistamine and started to improve within 45 minutes.

"Throughout the following day she noticed a marked fatigue but no skin rash, dyspnea or faintness," researchers noted.

After visiting doctors they then ran a test.

Skin prick testing with partner’s semen before and after he had consumed four Brazil nuts (AS Bansal, R Chee, V Nagendran, A Warner, G Hayman)

The researchers explained: "With the patient's consent, skin prick testing (SPT) was arranged to the partner's semen before and roughly two and a half-hours after he had been asked to consume 4 Brazil nuts.

"The results showed an unequivocal 7mm weal to the semen sample after, but not before, he had consumed Brazil nuts (figure). The patient was asked to avoid sexual intimacy if her partner had consumed nuts and to keep antihistamines and her adrenaline pen at hand.

"Unfortunately the couple separated soon afterwards and it was impossible to formally confirm the secretion of Brazil nut proteins into seminal fluid by Western blotting and other techniques."

They concluded: "To our knowledge, this is the first case of a severe food allergic reaction transferred by normal vaginal intercourse."