Bad breath, or halitosis, is an unpleasant odor emitted when speaking or exhaling. Most cases originate in the mouth; a minority reflect nose, throat, lung, stomach or systemic problems. Because the nose quickly adapts to surrounding smells, many sufferers are unaware of their own odor, while nearby people notice it immediately. Recognising the origin guides targeted removal.

1. Oral causes
   • Bacterial coating on the tongue: protein-rich debris trapped between filiform papillae is broken down into volatile sulphur compounds.
   • Gingivitis and periodontitis: pockets around teeth harbour anaerobic species that release malodorous gases.
   • Untreated caries, leaking crowns or impacted food: stagnant niches feed putrefaction.
   • Dry mouth (xerostomia): reduced saliva during sleep, mouth-breathing, stress, or medication allows bacterial overgrowth; typical “morning breath” is an example.
   • Smoking and alcohol: dry the mucosa, leave tar residues, and alter microflora.
2. Nose and throat sources
   • Chronic rhinosinusitis: post-nasal drip of infected mucus produces a stale smell.
   • Tonsilloliths: yellowish concretions in tonsillar crypts emit a sulphur-like whiff when crushed.
   • Foreign body in the nose (common in children): constant purulent discharge.
3. Systemic or gastric factors
   • Untreated diabetes with ketosis: sweet acetone smell.
   • Kidney failure: ammonia-like or fishy odor.
   • Reflux esophagitis: acid and partially digested food may carry an sour scent up to the oral cavity; true stomach-origin halitosis is rare.
4. Immediate removal strategies
   • Brush teeth twice daily plus floss or inter-dental cleaning to reduce plaque debris.
   • Clean the tongue: gentle brushing or a tongue-scraper from back to front reduces coating by up to 50 %.
   • Increase saliva: drink water frequently, chew sugar-free gum with xylitol, limit continuous coffee or alcohol.
   • Mouth-rinse: alcohol-free chlorhexidine or essential-oil formulations for 30 s after brushing; use only 1–2 weeks continuously to avoid staining.
   • Treat oral disease: visit a dentist for caries, pocket debridement, or extraction of hopeless teeth.
   • Quit tobacco and moderate alcohol: benefits noticeable within days.
   • Manage dry mouth from medicines: discuss dose adjustment or saliva substitutes with a physician.
5. Professional interventions
   Dental scaling and root-planing for periodontitis, endodontic treatment of infected teeth, tonsil stone removal, and management of sinus infection or reflux by appropriate specialists.

Summary table

Origin	Typical odor	First-line removal
Tongue coating	Sulphur, rotten	Tongue scraper + water intake
Gingivitis	Putrid, metallic	Dental scaling, floss daily
Dry mouth	Stale morning breath	Sugar-free gum, limit caffeine
Post-nasal drip	Stale, musty	Saline rinse, treat sinusitis
Smoking	Tar, dry	Quit tobacco, hydrate mucosa