Bad breath, also known as halitosis, is often caused by the breakdown of food particles in the mouth. Bacteria in the mouth feed on these food particles and produce gases that have an unpleasant odor. The most common culprit is poor dental hygiene, as food debris and bacteria can accumulate between teeth, on the tongue, and around the gums. Certain foods like onions, garlic, coffee, and dairy products can also contribute to bad breath. Medical conditions like sinus infections and acid reflux can also cause this problem. Maintaining good oral hygiene, using mouthwashes and toothpaste that target bad breath, and addressing any underlying medical conditions can help improve bad breath.