Everybody knows somebody with an allergy to pollen, dust, pet dander, or peanuts (maybe you even have one of these common ailments yourself). But you may be surprised about some of the lesser known materials, foods, or environments that an cause allergic reactions in certain people.
An allergic reaction occurs when the body misreads something that’s typically harmless as being dangerous, explains Kevin McGrath, MD, spokesperson for the American College of Allergy, Asthma, and Immunology. “The immune system creates special white blood cells, called antibodies, to defend against this apparent threat similarly to how it would fight an infection or illness,” he says. (That’s where symptoms like swelling, itching, runny nose, and wheezing come in.)
People must be born with a genetic predisposition to allergies, but scientists don’t know exactly why or how they become allergic to specific things. And while many allergens are quite common, others are much rarer. Here are some of the more interesting cases allergists have seen in their practice, and what you can do if you’re affected.
Inexpensive silver-colored jewelry is often made with nickelone of the most common causes of an itchy rash known as allergic contact dermatitis. About 17% of women and 3% of men have a nickel allergy, says Dr. McGrath; the gender difference is largely due to the fact that women have more exposure to nickel through jewelry (especially piercings), which raises their risk of becoming sensitized.
Switching to high-quality sterling silver or 14-karat gold jewelry usually solves this problem, says Dr. McGrath, although he has heard of very rare allergic reactions to gold, as well. “When people wear a lot of gold jewelry and a lot of makeup, the chemicals in the makeup can actually break down the gold and cause reactions with the skin.” For these people, he says, platinum is the best bet.
Cell phones and tablets
People with metal allergies may have trouble using cellular phones, PDAs, and tablet devices, (including iPhones and iPads), as these products often contain potential allergens nickel and cobalt. “People can get rashes on their face, ears, and hands, and irritation in the eyes if they touch their phone and then touch their eyes,” says Dr. McGrath.
“People think that it must be a chemical or something used in the growing process, but it’s actually part of the foodnot something you can wash off,” says Dr. McGrath. The good news? People can almost always eat these items cooked without experiencing symptoms.
People who are allergic to latex can experience an irritating rash when exposed to productslike condomsmade with the plant-based rubber. Some people can even have an immediate, life-threatening reaction called anaphylaxis, which can include difficulty breathing and swallowing.
Fortunately, many items that used to be made with latex (including gloves, hospital equipment, and balloons) are now made with safer materials, says Dr. Hummell. Most condoms still contain latex, but those with an allergy can use synthetic rubber or lambskin alternatives (here’s everything you should know about the nine most common types of condoms on the market).
Cosmetics and skin-care products
Chemicals in makeup, lotions, and sunscreens can sometimes cause a rash known as contact dermatitis, which may show up hours or days after exposure. An allergist or a dermatologist may be able to diagnose these types of sensitivities with a procedure called a patch test.
If you know that you’re sensitive to certain products, you can also test yourself before using a new formula. “Take a tiny bit and apply it to the same area of skin three days in a row at night before you go to bed,” says Dr. Hummell. “If you don’t have a rash by the end of the third or fourth day, you’re probably going to tolerate it well.”
This article originally appeared on Health.com.