The character's primary health concern is his lactose intolerance – his consuming dairy products results in flatulence. Leonard wears eyeglasses because of myopia and cannot see clearly without them. In one episode, when his glasses were broken at the movie theater, he had to surreptitiously return to his apartment and retrieve his backup glasses. In order to avoid detection by a sick Sheldon and Penny, who was nursing him, Howard and Raj helped him to navigate through the living room by using a helmet camera. Leonard also states in one episode that he suffers from sleep apnea. He also suffers from asthma, as it is apparent in multiple episodes that he needs his inhaler in order to perform a variety of activities including sports and sex. During his relationship with Leslie Winkle, he tells her that many members of his family have died from heart disease and thus he has a genetic disposition to the condition.