You could blame weeds, trees, and grasses if you start itching, sneezing, coughing, and wheezing. But the usual suspects aren't the only triggers. A host of household items—candles, chemicals, stuffed animals, and spices—may be the real culprits. "Many homes are filled with irritants, and if there's a high enough count of an irritant, you'll react," says Christopher Randolph, MD, an allergy expert at Yale University. Here, a rundown of 11 sneaky suspects—and how to stop them from bothering you.