What is the medical term for bad breath?

The medical term for bad breath is halitosis. It describes noticeably unpleasant breath odor and is also called oral malodor or fetor oris.

In most genuine cases, the source is inside the mouth rather than the stomach. Bacteria on the back of the tongue, between teeth, around the gums, or on dental appliances break down proteins and release volatile sulfur compounds. Gum disease, tooth decay, dry mouth, smoking, and some foods can all contribute. Odor is often stronger in the morning because the mouth is less active and produces less saliva during sleep.

The word halitosis combines the Latin halitus, meaning “breath,” with the Greek suffix -osis, meaning a condition or process. Physician Joseph William Howe used the term in an 1874 book, years before it became widely associated with mouthwash advertising in the 1920s.

Halitosis is not the same as anosmia, which means loss of smell; xerostomia, which means dry mouth; or dysgeusia, which means altered taste. Persistent bad breath can sometimes signal oral disease or, less commonly, a systemic condition, so treating the underlying cause matters more than masking the odor.