Bad breath affects people,its coined halitosis.The most common cause of halitosis is bad oral hygiene,foods with strong aroma .If particles of food are left in the mouth, their breakdown by bacteria produces sulfur compounds.Keeping the mouth hydrated can reduce mouth odor..

Halitosis or Bad breath from mouth is one of the most common reason that people seek dental care after tooth decay & gum disease. The most common cause of bad breath is poor dental hygiene. As bacteria break down particles of food, sulfur compounds are produced that cause odor. One of the main reasons for halitosis & gum diseases is calculus or tartar that is a form of hardened dental plaque. Calculus formation can result in bad breath, receding gums and inflamed gingiva. Brushing and flossing can remove plaque from which calculus forms; however, once formed, it is too hard and firmly attached to be removed with a toothbrush. # You may need to visit the Dentist for Calculus buildup to be removed with ultrasonic tools or dental hand instruments such as a periodontal scaler. # Cause of bad breath from the stomach can be due to poor digestion  or gastroesophageal reflux disease, or GERD. This condition is caused by acid coming back up the esophagus, causing a burning sensation in the chest or throat. It can also cause tooth erosion due to the acid in your stomach carrying into the mouth and weakening your teeth.