Many things can cause bad breath: a garlic-heavy meal, smoking, or slacking on your dental health routine. But if you have persistent bad breath with no obvious cause, it could be a sign of something more serious. When your gallbladder isn’t functioning normally or if gallstones are causing bile duct blockage, you may experience extremely foul-smelling that doesn’t improve with time or changing habits. Bad breath related to gallbladder issues is usually described as smelling like sulfur or rotten eggs. In addition to the odor, you may also have a sour taste in your mouth that you can’t get rid of. The bad breath may be accompanied by a yellow-colored tongue. Generally, tongues covered in a light yellow film are harmless, but they can be indicative of gallbladder or liver issues caused by an accumulation of bile.