Causes of Bad Breath

Problem	Possible cause or source of malodor
Odor after fasting, dieting, sleeping, taking medications, prolonged speaking, exercise	dryness in the mouth, insufficient saliva flow
Gums bleed and/or smell	gum problems, poor cleaning between teeth
Odor upon talking	postnasal drip on back of tongue
Odor at onset of menstrual cycle	swelling of gums
Small whitish stones with foul odor appear on tongue	tonsilloliths from crypts in tonsils
Odor appears suddenly from mouth of young children	onset of throat infection
Odor appears suddenly from nose of young children	foreign body placed in nose
Odor appears suddenly from entire body of young children	foreign body placed in nose
Taste or smell of rotten fish	trimethylaminuria (rare)
Odor in denture wearers	dentures kept in mouth at night or not cleaned properly
Odor from nose	sinusitis, polyps, dryness, foreign body, hindered air or mucus flow
Bad taste all day long	poor oral hygiene, gum disease, excessive bacterial activity on tongue

What Really Causes Bad Breath ?