Today, allergies affect about 50 million Americans each year. Penicillin, peanuts and cats are all very common allergens. But strange substances causing allergic reactions is more of a modern phenomenon. "If you lived 120 years ago, any allergy would have been considered unusual because they were virtually unknown before the late 19th century," says "The Allergy Solution" author Leo Galland, M.D.
"Initially, it was just pollen or bee stings. But now it's becoming substances that hide within other substances." Here are 10 oddball allergies that doctors have actually treated. And you probably haven't heard of them — unless you're one of the few people who suffer from them!