Southern Cross Medical Library

Southern Cross Medical Library

Bad breath is experienced by most people from time to time but for some it can be more persistent and noticeable. It can have negative effects on a person’s social or professional life and may affect their self-esteem.

Bad breath (also known as halitosis) can usually be improved with better daily oral hygiene and lifestyle changes. If bad breath does not go away with self-care, a dentist or GP should be seen in case bad breath is a sign of a more serious health condition.


Most cases of bad breath are due to poor oral hygiene and dental issues.

Not brushing and flossing each day leaves bits of food between and around the teeth. Those bits get broken down by bacteria in the mouth, producing bad-smelling gases. Dentures that are not cleaned regularly or are poorly fitted will also cause similar problems.

Dental issues, such as tooth decay, gum disease, and dental abscesses also contribute to bad breath.

Other things that can cause or contribute to bad breath, include:

  • Smoking: As well as leaving an unpleasant mouth odour, smoking and chewing tobacco dries out the mouth, reducing natural cleansing and an increase in odour-producing bacteria. Tobacco users are at increased risk of having gum disease, which is another cause of bad breath, and can lead to other health problems
  • Alcohol consumption: Drinking alcohol also causes a decrease in saliva production, which means less natural cleansing and more bacteria.
  • Some foods: Bacteria that cause bad breath use sugars as super fuel. Sugary foods, drink, lollies and gum may increase odour-producing bacteria (sugar-free mints and chewing gum are better alternatives for your breath). Strong smelling food like garlic, onion, and spicy foods, can also cause bad breath.
  • Dry mouth, which can be caused by: Sleeping (saliva production reduces while we sleep, which explains 'morning breath'); dehydration, various medical conditions including, stroke, Alzheimer’s and Parkinson’s disease, Sjögren's Syndrome, and mumps; radiotherapy for head and neck cancer; some medicines; and recreational drug use, e.g. methamphetamine, marijuana.
  • Certain medical conditions: medical causes of bad breath include diabetes, heartburnsinusitis, and tonsillitis
  • Dieting: Crash dieting or fasting can produce a sickly-sweet smell on the breath. This is due to chemicals called ketones produced by the breakdown of body fat.

Symptoms and diagnosis

One way to determine if you have bad breath is to ask someone who you trust to be honest and tell you if you have bad breath. You can also ask your dentist next time you have a check-up. A more private method to determine if you have bad breath is to lick your wrist, wait for the saliva to dry, and then smell the area. Scraping the back of your tongue with a spoon and then smelling the spoon is another method of self-testing for bad breath. You should see a dentist if you have the following signs or symptoms:

  • Bad breath that does not go away after treating it yourself for a few weeks
  • Gums that are painful, bleeding, or swollen
  • Toothache or adult teeth that are loose
  • Problems with your dentures.

A dentist will be able to say whether you have bad breath and might rate its intensity on a scale after smelling the breath from your mouth and from your nose. They may also rate the intensity of odour from a tongue scraping or length of dental floss. Some dentists have detectors that can identify specific chemicals responsible for bad breath.

Because problems inside the mouth are the most common causes of bad breath, a dentist will check your teeth, tongue, and gums and may also take X-rays. If a dentist is unable to find the cause of bad breath inside your mouth, they will suggest that you see your GP.

To look for other causes of bad breath, a GP will ask about other symptoms and do a physical examination. They might also do blood tests and examine the inside of your nose, throat, oesophagus, and stomach.


Most bad breath is due to problems in the mouth and will improve with better oral health routines (see the list below). Because bad breath can be due to a build-up of a bacterial film (plaque) on your teeth, the first steps are likely to include more regular brushing and flossing and use of an antibacterial mouth rinse and toothpaste to kill the bacteria.

A dentist might also recommend filling cavities and replacing faulty tooth restorations, both of which provide homes for odour-producing bacteria.

If you have gum disease, your dentist may refer you to a gum specialist (periodontist). Gum disease can cause gums to fall away from the teeth, which leaves deep pockets in which plaque builds up. These pockets are not easily reached with normal tooth brushing. Only specialised cleaning by a periodontist or hygienist is able to reach these pockets to remove the plaque. They can also educate you about improvements to your daily oral hygiene.

Treatment for bad breath that is not due to poor oral hygiene or dental issues will vary depending on the underlying medical condition. Your GP will determine the appropriate treatment for the specific cause of bad breath that is not related to problems inside the mouth.

Self-care and lifestyle changes

Things that you can do to treat bad breath by keeping your mouth and teeth healthy include:

  • Brush your teeth (gently) at least twice a day or after meals, for at least 2 minutes, with a soft-bristled toothbrush and using a fluoride toothpaste
  • Floss or use interdental brushes at least once a day to clean between your teeth
  • Use a tongue scrapper once a day to clean your tongue
  • Visit a dentist regularly, at least once per year
  • Chang your toothbrush every 3–4 months
  • Keep dentures clean and removing them at night before sleeping
  • Keep dental retainers, night guards, and mouth guards clean
  • Use antibacterial mouth rinse or toothpaste. Consider alcohol-free mouth rinse if mouth dryness is an issue for you.
  • Drink plenty of water to avoid dehydration and reduced flow of saliva
  • Quit smoking and don't use chewing tobacco products
  • Avoid sugary drinks and foods and other foods that cause bad breath
  • Decrease alcohol intake.


Mayo Clinic (2018). Bad breath (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. [Accessed: 13/01/23]

Mayo Clinic (2018). Dry mouth (Web Page). Rochester, MN: Mayo Foundation for Medical Education and Research. [Accessed: 13/01/23]

NHS (2021). Bad breath (Web Page). Redditch: National Health Service (NHS)

England. [Accessed: 13/01/23]

Hazell, T. (2022). Bad breath: Halitosis (Web Page). Leeds: Patient Platform Limited. [Accessed: 13/01/23]

Willacy, H. (2022). Common causes of bad breath (Web Page). Leeds: Patient Platform Limited. [Accessed: 13/01/23]

O’Toole, M.T. (Ed.) (2017). Halitosis. Mosby’s Dictionary of Medicine, Nursing & Health Professions (10th ed.). St Louis, MI: Elsevier.

Updated: January 2023

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The purpose of the Southern Cross Medical Library is to provide information of a general nature to help you better understand certain medical conditions. Always seek specific medical advice for treatment appropriate to you. This information is not intended to relate specifically to insurance or healthcare services provided by Southern Cross.