Halitosis (Bad Breath): Causes and How to Get Rid of It

What causes bad breath

In the mouth (most cases)

• Tongue coating: the rough back of the tongue traps bacteria, dead cells and food debris. These bacteria produce volatile sulfur compounds, the main cause of the "rotten egg" smell. A white or yellow coating at the back of the tongue is the most common single source.
• Gum disease: bacteria in pockets between gums and teeth produce strong odors. Look for bleeding when brushing, red or swollen gums, and gum recession. See periodontal disease.
• Tooth decay, broken fillings, and food trapped around crowns, bridges or braces.
• Dentures that are not cleaned properly or worn overnight.
• Dry mouth: saliva washes the mouth and controls bacteria. A dry mouth, from mouth breathing, many medicines, Sjögren's syndrome or dehydration, makes breath worse. See dry mouth.
• Morning breath: saliva flow drops during sleep, so almost everyone has some bad breath on waking.

Throat, nose and sinuses

• Tonsil stones: small, white or yellow, foul-smelling lumps that form in pockets of the tonsils.
• Sinusitis and post-nasal drip: mucus dripping down the back of the throat feeds bacteria.
• Tonsillitis and throat infections.
• A foreign body in the nose, a classic cause of one-sided smelly discharge and bad breath in young children.

Food, drink and habits

• Garlic, onions and spices: their odor compounds are absorbed into the blood and breathed out from the lungs, so brushing does not fully remove them.
• Coffee and alcohol, which also dry the mouth.
• Smoking and chewing tobacco.
• Very low-carbohydrate or fasting diets, which cause a fruity or acetone smell (ketosis).

Medical conditions (uncommon)

Reflux (GERD) is often blamed, but it is a less common cause than mouth problems. The stomach bacterium H. pylori has been linked to bad breath, but the evidence is limited.

How to tell if you have bad breath

It is hard to smell your own breath because your nose gets used to it. Ways to check:

• Lick the back of your wrist, let it dry for 10 seconds, then smell it.
• Gently scrape the back of your tongue with a spoon and smell the residue.
• Ask someone you trust.

Some people are convinced they have bad breath when others cannot detect it. This is called pseudo-halitosis, and when the worry is severe and persistent, halitophobia. A dentist can measure breath odor objectively.

How dentists and doctors find the cause

A dentist will look at your teeth, gums, tongue, fillings and dentures and check for gum pockets. They may rate the smell directly (organoleptic test) or with a device that measures sulfur gases. If the mouth looks healthy, a doctor will check your nose, sinuses and tonsils and ask about reflux, diabetes and other conditions. Blood tests for blood sugar, kidney and liver function, or a referral to an ear, nose and throat specialist may follow. The halitosis condition page covers diagnosis and specialist treatment in more detail.

How to get rid of bad breath

1. Clean your tongue every day. Use a tongue scraper or your toothbrush, working from back to front. This removes the main source of odor.
2. Brush twice a day for 2 minutes with a fluoride toothpaste, paying attention to the gumline.
3. Clean between your teeth daily with floss or interdental brushes.
4. Stay hydrated. Sip water through the day. Sugar-free gum or lozenges stimulate saliva.
5. Use a mouthwash containing chlorhexidine, cetylpyridinium chloride or zinc for short-term control. Alcohol-based mouthwashes can dry the mouth. Mouthwash masks odor briefly, but it does not replace cleaning.
6. Clean dentures every day and take them out at night.
7. Stop smoking and cut back on alcohol and coffee.
8. Eat regular meals, including breakfast. Crunchy fruit and vegetables help clean the teeth.
9. See a dentist for a checkup and professional cleaning, at least once or twice a year.

Treatment of other causes includes gum disease therapy, filling cavities, saline rinses or steroid sprays for sinus problems, treating reflux, and, if tonsil stones keep recurring, gargling or sometimes tonsil removal.

Frequently asked questions

What is halitosis?

Halitosis is the medical term for bad breath. It means a persistent unpleasant odor from the mouth. In most cases it is caused by bacteria on the tongue and in the gums releasing sulfur gases. Good oral hygiene, especially tongue cleaning, and dental treatment fix most cases.

Why do I have bad breath even after brushing?

Brushing teeth alone often misses the back of the tongue, where most odor-causing bacteria live. Gum pockets, tonsil stones, dry mouth, and foods like garlic that are breathed out from the lungs can also cause persistent breath odor. Add tongue cleaning and flossing, and see a dentist if it continues.

Can bad breath be a sign of a serious illness?

Occasionally. Fruity breath can signal diabetic ketoacidosis, an ammonia smell can mean kidney failure, and a musty smell can mean severe liver disease. These come with other obvious symptoms. Most bad breath, however, comes from the mouth and is easily treated.

Does mouthwash cure bad breath?

Not on its own. Mouthwash reduces bacteria and masks odor for a few hours, and antibacterial types such as chlorhexidine or cetylpyridinium chloride help more than plain freshening rinses. Lasting results need tongue cleaning, brushing, flossing and treatment of gum disease or decay.

How do I know if I have bad breath?

Lick your wrist, let it dry and smell it, or scrape the back of your tongue with a spoon and smell that. Asking a trusted person is often the most reliable test. A dentist can also measure breath odor if you are unsure.