Bad breath (halitosis) is very common and people often do not notice it themselves. The good news: most of the causes are in the mouth and can be treated.
Where does bad breath come from?
In the great majority of cases of persistent bad breath, the source is the mouth itself. Bacteria in the mouth produce sulphur gases as they break down food debris, shed cells and proteins in saliva. These gases are responsible for the smell.
Causes in the mouth
- Bacterial coating on the tongue: The rough back of the tongue is an ideal home for bacteria; it is the most common source of bad breath.
- Gum disease: Bacteria collecting in gum pockets produce a strong smell. If bleeding gums and persistent odour occur together, gum treatment may be needed.
- Decay and faulty fillings: Food collects in cavities and under fillings and crowns with open edges.
- Partly erupted wisdom teeth: Debris trapped under the gum causes infection and odour.
- Dry mouth: Saliva washes the mouth and keeps bacteria in balance. When there is less of it, odour increases. Morning breath is also caused by reduced saliva flow at night.
- Dentures that are not cleaned: Removable dentures and the undersides of bridges become a source of odour if not cleaned regularly.
Causes outside the mouth
Less often the smell comes from elsewhere: tonsil stones, sinusitis and postnasal drip, acid reflux, uncontrolled diabetes, and kidney and liver disease are among the causes. If no cause is found at the dental examination, your dentist refers you to the relevant specialty.
Garlic, onion, smoking and alcohol cause temporary odour. Long periods without eating and very low-carbohydrate diets can also give the breath a characteristic smell.
What you can do at home
- Clean your tongueOnce a day, scrape gently from back to front with a tongue cleaner or your brush. It is the single most effective step.
- Clean between your teethUse floss or an interdental brush every day. Smell the floss afterwards; if it smells bad, that is where the source is.
- Brush twice a dayEspecially do not skip brushing before bed.
- Drink plenty of waterIt reduces dry mouth. Sugar-free gum increases saliva flow.
- Clean your dentureBrush a removable denture every day and take it out at night.
Mouthwash, gum and mints only mask the smell for a short time. They do not remove the cause; alcohol-based mouthwashes can make things worse by drying the mouth.
When should you see a dentist?
If the odour lasts more than two weeks despite good oral care, have an examination. The gums, decay, old fillings and the tongue are assessed. Most of the time the problem is solved with scaling, treatment of decay and good care habits.
How can you tell if your own breath smells?
People get used to their own smell and find it hard to notice. Breathing into your palm is not reliable. Scraping the back of your tongue with a clean spoon and smelling it a few seconds later, or smelling your floss, gives a better idea. The most reliable way is to ask someone close to you.
Frequently asked questions
Does bad breath come from the stomach?
Rarely. Contrary to popular belief, most persistent bad breath starts in the mouth. Stomach problems such as reflux are a less common cause.
Is morning breath normal?
Yes. Saliva flow falls during sleep and bacteria multiply. Morning breath that goes after brushing and breakfast is not a sign of disease.
I think I have bad breath but nobody says so. What should I do?
Some people worry about odour when there is none. A dental examination both shows whether there is a real cause and puts your mind at rest.
This article is for general information and is not a substitute for diagnosis or treatment. If you have a complaint, please see your dentist.