What causes bad breath?

Bad breath...halitosis, whatever you call it, it's something almost all of us suffer from at some point in our lives. So what causes this timeless turnoff, and what can be done about it?

Causes of bad breath

The odor is caused by wastes from bacteria in the mouth, the decay of food particles, other debris in your mouth and poor oral hygiene. The decay and debris produce a sulfur compound that causes the unpleasant odor.

Bad breath also may occur in people who have a medical infection, diabetes, kidney failure or a liver malfunction. Xerostomia (dry mouth) and tobacco also contribute to this problem. Even stress, dieting, snoring, age and hormonal changes can have an effect on your breath. An odor that comes from the back of your tongue may indicate postnasal drip.

To eliminate bad breath, you need to eliminate some of the most common causes of it:

Infected Gums

This can be one of the most obvious causes of bad breath. To get gums back into shape, brush thoroughly and often with a soft-bristle brush, and get into the habit of regular flossing. Your dentist can advise you of the appropriate treatment for all dental problems.

Dirty teeth

"There are more animals living in the scum on a man's teeth," claimed a 17th-century scientist, "than there are men in a whole kingdom." Whether or not there is any truth in this, teeth can certainly collect their fair share of odor-producing debris. Best for keeping oral bacteria to a minimum is frequent brushing (with or without toothpaste) or even just swishing the mouth with water.

A foul tongue

Many dentists believe that keeping a clean tongue may be even more effective at arresting offensive breath than keeping teeth clean. Tongue-brushing is something the ancient Romans did regularly; Mohammed also encouraged his followers to practice the custom. Brush very gently, with a soft-bristle brush and keep away from the very back of your tongue as this may cause a gagging reaction.

An empty stomach

Yes, skipping meals can cause foul breath as it reduces the production of saliva needed to flush away bacteria from teeth, tongue and gums. Stress can also lead to a dry mouth, which can cause double trouble when coupled with the increase in stomach acid that stress can cause. Chewing gum and lozenges can step up saliva flow, as can between-meal snacks such as fresh fruits and vegetables.


Because it sours the mouth and disrupts digestion, smoking has been linked to bad breath for centuries. Chewing tobacco can also foul the breath.

Overuse of mouthwashes

Ironic as it may sound, mouthwashes may actually worsen a bad breath problem by irritating oral tissue, although it does mask bad odors temporarily. For an emergency pick-up, try a quick rinse with a mix of water and a few drops of peppermint oil.

Some information courtesy of the Academy of General Dentistry.
Last updated: February 2012

The oral health information on this website is intended for educational purposes only. You should always consult a licensed dentist or other qualified health care professional for any questions concerning your oral health.

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