Bad breath happens to everyone at some point, and research suggests that between 25% and 50% of people are regularly affected. Known medically as halitosis, bad breath is best tackled by addressing the cause rather than simply disguising the problem with breath fresheners.

By Wallace Health I Medically reviewed by Adrian Roberts.
Page last reviewed: October 2018 I Next review due: October 2021

Causes of bad breath

Most bad breath is due to poor oral hygiene, food or drink, or dehydration, but sometimes it can be a sign of an underlying health problem. The possible causes are wide-ranging and include:

  • Poor oral hygiene – food remaining on or between your teeth is broken down by bacteria, which release unpleasant smells; this can lead to tooth decay and gum disease, worsening the problem
  • Diet – some foods such as raw onions, garlic and spices can produce odours after digestion, when they enter your bloodstream and reach your lungs
  • Dry mouth – saliva helps keep bacteria under control, so if you don’t produce enough, bacteria will build up
  • Smoking – the chemicals in cigarettes directly cause bad breath as well as damaging gums, increasing the risk of gum disease
  • Alcohol – it’s dehydrating, increases the bacteria linked to gum disease and raises the risk of acid reflux, another cause of bad breath
  • Crash dieting and low-carbohydrate diets – your body rapidly breaks down fat stores, releasing chemicals called ketones that give off a sweet, sickly smell
  • Underlying medical conditions – these can range from short-term infections to long-term or serious problems such as diabetes

Talk to your doctor if you’re concerned about symptoms

You can book an appointment with a Spire private GP today.

Conditions related to bad breath

Sometimes, bad breath has an underlying medical cause such as:


This includes infections of the mouth, nose, throat and lungs, such as dental abscesses, sinusitis, tonsillitis and bronchitis.

Gastrointestinal conditions

  • Acid reflux, when stomach acid leaks back up into your oesophagus (gullet), causing a burning sensation
  • Infection with the bacterium Helicobacter pylori, which increases risk of stomach ulcers


If diabetes is undiagnosed or poorly controlled, your body isn’t able to break down glucose for energy, so it breaks down fat instead. It’s this that causes the production of chemicals called ketones, which have a sweet, fruity odour.

Other causes are:

  • Sjögren’s syndrome
  • Liver or kidney problems
  • Some cancers

Getting a diagnosis for bad breath

If you think you have bad breath, see your dentist. They can check for signs of tooth decay, gum disease and infections and can spot signs of some serious conditions such as mouth cancer. They may recommend:

  • A visit to the hygienist who can give your mouth and gums a thorough clean and advise you on dealing with gum disease
  • A visit to your GP who can assess any possible medical cause


To determine possible causes, your GP may:

  • Ask about other symptoms you may have
  • Get you to breathe out from your nose and your mouth separately and smell your breath to help determine the cause
  • Refer you for blood tests to rule out or diagnose other conditions

Treatments for bad breath

Treatments vary widely, depending on the cause. Here are some of the most common solutions for getting rid of bad breath:

Good oral hygiene routine

This will involve:

  • Brushing twice a day for two minutes at a time
  • Flossing or using an interdental brush once a day
  • Brushing your tongue to remove bacteria daily
  • Using a mouthwash that doesn’t contain alcohol – your dentist can advise
  • Changing your toothbrush at least every three months
  • Going for regular dental hygiene appointments and check-ups

Lifestyle changes may include:

  • Quitting smoking
  • Drinking plenty of water
  • Avoiding too much pungent food and drink such as onions, garlic, spices and coffee
  • Limiting alcohol intake

Other treatments may include:

  • Management or treatment for whatever medical condition is causing your bad breath
  • Changing any medication if your doctor thinks it's causing your bad breath

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