What Causes Bad Breath (And How to Treat It)

why do i have bad breathBad breath is fairly common, but in most cases it's temporary and goes away after you brush your teeth.

More severe bad breath (halitosis) is thought to affect around 2.4 percent of adults. As well as being a source of embarrassment and lost confidence, it could also be a symptom of an underlying health problem that needs urgent attention.

If you're concerned about your breath, the best thing to do is make an appointment with your dentist. By examining your mouth and asking questions about your diet and lifestyle, your dentist will aim to work out what's causing your breath to smell so they can recommend the best treatment to fix it.

How do I know if I have bad breath?

It can be hard to tell if you have bad breath, because the brain quickly filters out stimuli that it gets used to. You might be familiar with this experience if you've ever visited a farm and been overwhelmed by the smell of manure, wondering how anyone could bear to be around it all day... only to stop noticing it yourself before long.

Even if you can't smell your own breath, other people may be able to when you talk or breathe close to them, which is where the embarrassment lies. If you're worried that people might be flinching or even avoiding you, ask someone you trust to tell you the truth.

While bad breath is usually the most obvious symptom of halitosis, other signs can include:

  • persistent dry mouth
  • thickened saliva
  • a white coating or burning sensation on the tongue
  • a sour, bitter or metallic taste in your mouth
  • needing to clear your throat

If your bad breath is accompanied by any of these or other symptoms, it's possible it's related to an underlying oral health problem, so home remedies alone might not be enough to freshen your breath.

What is bad breath a sign of?

Bad breath is a common symptom of oral health problems, and it can sometimes have more than one cause. Knowing what's causing your halitosis can be the key to effective long-term treatment. The most common reasons for bad breath are outlined here.


Most cases of halitosis are caused by bacteria. The average mouth is host to hundreds of different types of bacteria, even when you follow good oral hygiene. Some of these feed on particles of food left on your teeth and release unpleasant smelling by-products. That's one of the reasons why regular tooth brushing is important, as well as flossing to reach places a toothbrush can't.

The bacteria that produce the sulphurous odour associated with bad breath live at the back of the tongue and in the throat. If you have a high level of these bacteria, they'll break down proteins in the food you eat and produce volatile sulphur compounds (VSC), which are carried on your breath. This can usually be remedied by using an antibacterial mouthwash prescribed by your dentist, which kills bacteria as well as freshening breath.

Food and drink odours

Temporary bad breath is usually a result of consuming food and drink with strong odours. Their distinctive smells can linger in the mouth until you brush and floss, and even afterwards if you don't remove all traces.

Foods that contain sulphur compounds, such as garlic and onions, can release these into the bloodstream, causing bad breath to linger even longer. Coffee and alcoholic drinks can cause breath to smell and have the added effect of reducing saliva, which is important for rinsing the mouth of bacteria.

If you think your bad breath might be linked to your diet, you could consider giving up certain foods and drinks or reducing their effect by rinsing your mouth with water and chewing sugar-free gum. You shouldn't brush your teeth straight after eating or drinking though, as acids left on the teeth can weaken the enamel and cause it to be damaged when rubbed.


Smoking can reduce the sense of smell (as well as taste), so you might not know how your habit's affecting the people around you. Unlike food and drink odours that typically only linger in the mouth, the smell of cigarette smoke lingers in the lungs and the throat, so it may still be smelled for hours afterwards.

As well as being a direct cause of bad breath, smoking also increases oral health risks that can make halitosis worse, including gum disease and dry mouth. With all the other health risks associated with tobacco use, improving your breath probably isn't the main motivation to quit smoking, but it's another one to add to the pile.

Poor oral hygiene

Warm and wet mouths are the perfect environment for bacteria to thrive, especially if you leave food for them on your teeth by not cleaning your mouth properly after you eat. Consuming too much sugar or starch in snacks and soft drinks also feeds the bacteria in plaque that are responsible for tooth decay and gum disease.

You can keep bacteria under control by practising good oral hygiene every day. As well as brushing your teeth at least twice a day and daily flossing, brushing your tongue from back to front could make a big difference to reducing bacteria. You can gently scrape your tongue using the back of your toothbrush head or using a specialised tongue scraper.

If your dentist thinks you need to improve your oral hygiene, they may recommend brushing more often or adding a mouthwash to your routine. If you have braces, dentures or other dental work, these need to be cleaned just as thoroughly as teeth to remove trapped food and bacteria.

Gum disease

If your bad breath is accompanied by swollen, painful or bleeding gums, these can be symptoms of gum disease (also called periodontal disease). This is caused when bacteria in plaque build up along the gum line, causing irritation and triggering your body's inflammation response.

Around one in five Australians is thought to have gingivitis, which is the early stage of gum disease. This can often be treated by improving your oral hygiene at home or visiting your dentist for a cleaning and scaling treatment.

If gingivitis develops into periodontitis, this can cause permanent damage such as receding gums and eventually tooth loss. Severe gum disease needs to be treated by a dentist.

Dry mouth syndrome

If you have bad breath, a bad taste in your mouth, thick saliva and your mouth always feels dry, you may have a condition called dry mouth syndrome (or xerostomia). This affects the function of the salivary glands, meaning there's less saliva to moisten your mouth and clean away leftover food and bacteria, contributing to bad breath and oral health problems.

Dry mouth syndrome is a side-effect of many medications and some medical treatments. It can also be linked to various health conditions, nerve damage, feelings of stress and anxiety, snoring and alcohol, tobacco or drug use.

Dry mouth may be treated by changing medications or treating other likely causes, but it's sometimes a permanent problem. Your dentist may recommend products to hydrate your mouth and other ways to reduce discomfort, such as drinking plenty of water, avoiding foods that irritate your mouth and chewing sugar-free gum to help stimulate saliva.

Health conditions

Halitosis can be a symptom of infections of the mouth and sinuses, such as oral thrush or chronic sinusitis (if you also have nasal discharge). Acid and bile reflux from the stomach may also leave odours on the breath.

If you and your dentist rule out the common causes of bad breath, it could be a symptom of another underlying health condition, although this is relatively rare. Some of these conditions include diabetes and diseases of the kidney and liver.

If this may be a possibility, your dentist will recommend that you make an appointment with a doctor. They may be able to give you a diagnosis or will refer you to a suitably qualified specialist who can diagnose any problem and discuss treatments.

How do I get rid of bad breath?

There's no single treatment for bad breath or halitosis. Breath sprays, mints and sugar-free gum may provide temporary relief, but if the problem persists, you should aim to treat the cause rather than just the symptom.

Depending on what's causing it, bad breath can sometimes be relieved by:

  • improving your oral hygiene – brushing your teeth, flossing and gently scraping your tongue
  • avoiding pungent food and drink, tobacco and alcohol
  • drinking plenty of water, especially tap water containing fluoride that helps to strengthen teeth
  • eating crunchy or chewy foods and sugar-free gum to stimulate saliva
  • gargling with an antibacterial mouthwash
  • visiting your dentist for regular check-ups and teeth cleaning

Bad breath treatments in Sydney CBD

If you want to know more about what causes bad breath and ways to treat it at home or at the dental clinic, our dentists at Sydney CBD Dental are always happy to help.

Call us today on (02) 9232 3900 or make an appointment at our clinic at 300 George Street.


Better Health Channel. Halitosis or bad breath [Online] 2012 [Accessed May 2020] Available from: https://www.betterhealth.vic.gov.au/health/ConditionsAndTreatments/halitosis-or-bad-breath

Healthdirect. Dental care tips [Online] 2017 [Accessed May 2020] Available from: https://www.healthdirect.gov.au/dental-care-tips

Healthdirect. Gingivitis and halitosis [Online] 2017 [Accessed May 2020] Available from: https://www.healthdirect.gov.au/gingivitis-and-halitosis

Healthdirect. Dry mouth syndrome [Online] 2018 [Accessed May 2020] Available from: https://www.healthdirect.gov.au/dry-mouth-syndrome