8 Surprising Causes of Bad Breath

Halitosis can't always be brushed or flossed away—but having breakfast might help defeat it.

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Has a friend or significant other gently hinted that your breath is, um, pungent? (Many halitosis sufferers can't tell.) Brushing and flossing more diligently may do the trick, and U.S. News's Sarah Baldauf offered other suggestions earlier this year. But a few more minutes at the sink won't always help, say experts. Here are eight causes of bad breath that may surprise you: 

Medications. Saliva rinses away bacteria that foul the breath, and many drugs, among them antidepressants, diuretics, and even aspirin, can dry the mouth.

Bacteria. The stink-creating kind mostly hang out on the tongue, happily churning out gases as they munch on food particles and substances broken down from saliva, and multiply at night, when the salivary glands slow down (hence morning breath). Some people harbor more species of malodorous bacteria than others do, which may be why certain individuals are especially halitosis-prone. This month, a study in the Journal of Medical Microbiology suggests that H. pylori, the same bug that is often responsible for stomach ulcers, can cause bad breath and gum disease if it finds a home in the mouth.

Respiratory tract infections. Tooth and gum infections are recognized sources of bad breath. But so are bronchitis, sinusitis, and even a cold. RTIs break down tissue, starting a flow of cells and mucus that feed bacteria that create foul odors. 

Skipping breakfast. Besides the well-established advantages to body and mind of having a good breakfast, it helps quell morning breath by stimulating saliva production and scrubbing bacteria from the tongue. (But lay off the sardine-onion sandwich.)

Diet. Foods high in protein or dairy products generate large amounts of amino acids, which are fodder for bacteria. A diet low in carbs burns stored fat, creating toxic-smelling ketones. And last year, researchers linked bad breath with obesity, although the basis is unclear.

Mouth breathing. Any condition that dries the tissues of the mouth, preventing saliva from washing away bacteria, encourages bad breath. Candidates include sleep apnea, snoring, and asthma.

Ongoing illnesses. A potent breath can signal particular diseases. Kidney failure produces a fishy smell and uncontrolled diabetes generates fruity fumes, for instance.

Alcohol. Heavy alcohol consumption also can dry out the mouth.