All About Halitosis Halitosis is chronic bad breath and affects as many as 80 million people. In most cases, the odor originates from the tongue and gums. Specifically, the odor comes from wastes generated by the 600 types of naturally-occurring bacteria found in the average human mouth, decaying food particles, other debris in the mouth, and poor oral hygiene. Other sources include: gum disease, Xerostomia (dry mouth), tobacco, infected post nasal drip, a medical infection,