If you're dealing with asthma, you know how scary it can be to suddenly find yourself short of breath. (Breathing: So many people take it for granted.) To deal, you tote your inhaler with you everywhere you go, just in case. But you might want to make an appointment with your doctor to make sure you've really got asthma. According to a new study published in JAMA, "Reevaluation of Diagnosis in Adults With Physician-Diagnosed Asthma," doctors misdiagnose asthma a third of the time. The study looked at 613 Canadian men and women who were recently diagnosed with asthma. Over the course of four visits, researchers "gave them a series of drug challenges and spirometry, a physical test of breathing capacity, to confirm or rule out the disorder." In 203 of the cases, doctors determined that the patients didn't actually have asthma. Because they were diagnosed solely on symptoms, as opposed to undergoing actual spirometry tests, they were misdiagnosed. "If you have shortness of breath, wheeze or cough, you should suggest that the doctor order a spirometry test," lead author Shawn D. Aaron, MD, said. "It’s a quick test with no risks or side effects that can predict asthma or other respiratory conditions." Before you reach for your inhaler again, consider giving your doctor a ring to see if you're experiencing something other than an asthma attack.