Everything you’ve ever wanted to know about dreaded bad breath…

Halitosis is the medical term for an unpleasant odour on the breath. It may be harmless, or a sign of a dental issue, but sometimes it signals a worrying medical problem. Either way, if it happens to you, you’ll want to work out what’s causing it and do something about it. You may be blissfully unaware that you have bad breath and just wondering why other people keep their distance. Or you may have been told about it by a concerned friend or family member. It may be too embarrassing to talk about it to a friend, but don’t be too embarrassed to ask your doctor. We help people to deal with this problem all the time.

Causes of bad breath

The odour of your breath can vary depending on your diet, the time of day, your state of hunger, your stress levels and, for women, the time of your menstrual cycle. The first and most obvious place to start looking for causes of halitosis is in the mouth.

1 Poor dental hygiene
Halitosis is most commonly caused by the action of microorgan-isms or debris left around the teeth and gums. When microorganisms break this debris down in the alkaline environment of the mouth, the rotting process causes the release of chemicals, particularly sulfide compounds. A poor dental routine that allows build-up of food particles around the teeth, gums and tongue promotes bacterial overgrowth. That creates an odour, as well as plaque on the teeth, irritation of the gums (gingivitis) and dental caries (tooth decay).

2 Dry mouth
Saliva keeps your mouth hydrated and has a natural anti- bacterial component. This means that conditions that cause salivary gland problems, some autoimmune diseases (such as Sjögren’s syndrome), medication side effects (particularly some antihistamines and antidepressant medications) or persistent mouth breathing related to a congested nose or sinuses will all affect the smell of your breath. Excessive alcohol intake can also contribute to mouth dryness.

3 Mouth, nose and throat infections
Infections or inflammation in the throat or oral cavity, such as bacterial or viral tonsillitis; the fungal infections that can occur with certain medications, such as steroids inhaled to treat asthma; or sinusitis with a post-nasal drip can all create an unpleasant odour in the mouth.

4 Medical problems beyond the mouth and throat
Gut infections, such as the ulcer-causing bacterium Helicobacter pylori or giardiasis, can cause bad breath. Some medical problems are associated with distinct breath odours, including diabetes (sweet), gastro-oesophageal reflux (acidic), liver disease (ammonia), kidney disease (fishy) and intestinal blockage (faecal). Cancer in the mouth, nose, throat, sinuses, oesophagus, stomach or airways can also generate an unpleasant odour in the breath.

5 Medications
Some medications are notorious for causing bad breath. These include some antihistamines, some antidepressants, anticholinergics (used to treat a variety of conditions), diet pills that reduce appetite, some blood pressure medications, antipsychotics, anti-Parkinson’s agents, diuretics, decongestants and sedatives. Check with your doctor or pharmacist whether any of your medications is likely to cause halitosis.

6 Smoking
As we all know, smoking tobacco gives the breath a distinctly foul odour. The stale smell of the inhaled tobacco can linger in the lungs and airways for hours after smoking a cigarette. Many of the inhaled toxic chemicals in tobacco smoke can linger in saliva, and inhaling hot smoke also dries out the tissues in the mouth and throat and causes gum inflammation.

7 Foods
Certain foods can cause halitosis, either because of the effect those foods have on the environment in your mouth directly (like meat stuck between your teeth), or as a result of a chemical reaction created by the digestive process. You are probably aware that the foods most likely to cause halitosis include garlic, onion, curry, broccoli, cabbage, leek, salami and other processed meats, and strong cheeses. Coffee is another common cause because of its high sulfur content, and can also cause mouth dryness because caffeine slows down saliva production.

Eliminating bad breath

  • Speak to your doctor about possible underlying causes.
  • Arrange a dental appointment. Have dental checks every six months and any oral hygiene treatments you need.
  • Drink plenty of water.
  • Swish a solution of water and probiotics around your mouth after flossing and brushing daily for a week. (Over- the-counter temporary rinses often contain alcohol, which reduces production of saliva and dries out the mouth in the long run. If you like to use home remedies, eating citrus fruits and chewing fresh herbs such as mint, parsley and rosemary, and fennel or anise seeds have been used to neutralise bad breath).
  • If you have a medical condition causing dry mouth (such as Sjögren’s syndrome), you may need to use a special saliva substitute.
  • Eat regularly, including plenty of fruit and vegetables, and reduce your intake of foods that make your breath smell worse.
  • Give up smoking.
  • Reduce your alcohol and coffee intake or avoid them completely.
  • Brush your teeth after every meal, and floss between your teeth daily.
  • Replace your toothbrush every season or more often – especially if you’ve been sick.


This is an extract from The Mystery Gut by Prof Kerryn Phelps AM, Dr Claudia Lee & Jaime Rose Chambers, published by Pan Macmillan, available now.