Eventually she broke up with that man, and started seeing one who was dedicated to using condoms. “It wasn’t an issue until one night when we were lying in bed after sex and my tongue suddenly began to swell,” Maura recounts. “My partner saw what was happening, screamed, ‘You’re asphyxiating!’ and grabbed my inhaler…he was able to cram my inhaler into the corner of my mouth, and he just started firing it. Luckily, I was still breathing enough to draw the medicine into my lungs.”
Maura, who also has asthma and a number of allergies, believes that the condom had leaked. She and her long-term partner are now even more careful about condom usage. Until it happened to her, she didn’t know it was possible to be allergic to semen, she says.
Though they’re extremely rare, some people suffer severe immune reactions to other people’s bodies. These often-misunderstood conditions can affect not just health, but also work, relationships and generally how someone moves through the world. But how exactly these reactions unfold, and what causes them, remains largely mysterious. Are they true allergies, or something else? As scientists begin to glean some hints, these strange responses are uncovering insights into the chemistry of our bodies and the quirks of the human immune system.
From the skin
Often, sensitivity to another person’s body relates to the external products turning up in that body. For instance, the skin can carry synthetic fragrances, including in deodorants and aftershaves. Over 150 fragrances are linked to contact allergies.
The trigger is not always clear. One American woman with a severe version of mast cell activation syndrome, in which infection-fighting cells start malfunctioning, developed debilitating allergic reactions to her husband’s scent. Sabine Altrichter, a doctor at Kepler University Hospital in Austria, says that while the link isn’t proven, some patients with mast cell disorders suspect that they’re sensitive to natural body odours or chemicals emitted by other people’s skin.