You probably know plenty of people who are allergic to ragweed, and maybe a few who break out in hives when they eat peanuts or shellfish. But have you ever met someone who’s allergic to glitter or semen? Odd allergies like these really do exist, though they’re pretty rare—which makes them harder to diagnose, says Clifford W. Bassett, MD, an assistant clinical professor of medicine at NYU School of Medicine.
Check out nine of the most bizarre allergies that Bassett and other allergists occasionally come across. (Want to pick up some healthier habits? Sign up to get healthy living tips delivered straight to your inbox!)
Crafters beware: Glitter can do worse things than get stuck to your clothes. The chemical compounds used to coat mica flakes to make them shiny may cause hives and rashes, though this allergy is rare and Bassett has never seen it in his practice. If glitter bothers you, the mica found in mineral makeup might, too.
This one beats the “I have a headache” excuse. A protein found in semen can cause symptoms ranging from burning and itching to shortness of breath. “You can even have a life-threatening reaction,” says Bassett. Women who have this problem and are trying to get pregnant can work with a specialist to become desensitized.
Some people have a legit excuse to skip the gym. “It’s not common, but I do have several dozen patients with it,” Bassett says. About 65% of people with an exercise allergy find that sweating because of exercise is a sufficient trigger, while 35% react only when they combine certain foods (such as wheat) with exercise. “Some people can exercise in the morning before breakfast and be good to go, but if they exercise after eating that brings on an attack,” he explains. Symptoms may include hives, swelling, nausea, diarrhea, low blood pressure, and trouble breathing. “If you have it, you never want to exercise alone,” says Bassett.
Aquagenic pruritus. That mouthful is the official term for an H2O allergy. “It’s extremely rare,” says Bassett. Contact with water of any temperature can cause a sufferer to develop red and/or itchy skin on the arms, chest, legs, or back. Experts haven’t been able to get to the bottom of what causes it; if you have it, you’ll have to work closely with an allergist to figure out how to keep clean and minimize your discomfort.
OK, so you can’t be allergic to all footwear, but some people are allergic to one or more of the components, such as leather, glue, varnish, resins, and rubber. “It can be an immune-based reaction or irritant,” Bassett says. “We test people every day to find out what it is.”
No, it’s not the electromagnetic waves that can cause a rash, but rather what your phone is made of. “I do a lot of testing for metal allergies,” Bassett explains. “When people come into my office with a facial rash, I check their phones.” Often patients have a nickel allergy, which is very common.
Yes, you can be allergic to your purse. People who have this allergy will get contact dermatitis (a catchall term for a skin condition resulting from contact with irritants or allergens) when they touch leather goods. “Any type of skin allergy can present itself the same way: itching, burning, and redness,” says Bassett.
Some people are so sensitive to pressure that if they trace a word on their skin with their fingernail, you’ll be able to read it. (This condition is called dermatographism, which means “writing on the skin.”) Bassett estimates that this condition, which causes the skin to get itchy and red, affects about 4% of the population. OTC or prescription antihistamines usually help.
Jumping into a cold swimming pool or stepping out into frigid weather (without properly bundling up) can cause some people to break out in hives. Others may get dizzy and pass out, thanks to their blood pressure plummeting.