Bad breath is a common problem that can affect anyone at any age.

About one in four people are thought to have bad breath (halitosis) on a regular basis.

What causes bad breath?

There are a number of things that can cause bad breath. It's usually the result of poor oral hygiene. If bacteria build up in your mouth, the toxins produced can cause your breath to smell. 

Bacteria break down pieces of food in the mouth, and may release an unpleasant-smelling gas. Any food trapped on your teeth – particularly between them – is broken down by bacteria, which may cause bad breath.

Persistent bad breath can sometimes be a sign of gum disease. Eating strongly flavoured foods, such as onions and garlic, can also cause your breath to smell, as can smoking and drinking alcohol.

Occasionally, bad breath can occur after an infection or illness, or as a result of taking certain types of medication.

Read more about the causes of bad breath.

Treating and preventing bad breath

Improving your oral hygiene is usually enough to cure bad breath and stop it happening again.

To improve your oral health, make sure you:

• floss between your teeth daily
• brush your teeth and gums regularly
• clean your tongue regularly

Read more about treating and preventing bad breath.

When to seek medical advice

See your dentist, dental hygienist or dental therapist first if you still have bad breath after making changes to improve your dental hygiene.

You may also need to visit your GP as there may be a medical cause that needs to be investigated.

Don't try to hide the smell of your breath when seeking medical advice as it may make it more difficult to find out what's causing the problem.

There are a number of possible causes of bad breath (halitosis).

Poor oral hygiene

The most common cause of bad breath is poor oral hygiene. Bacteria that build up on your teeth – particularly between them – as well as your tongue and gums, can produce unpleasant-smelling gases. These bacteria are also responsible for gum disease and tooth decay.

If you don't floss and brush your teeth regularly, any food trapped between your teeth will be broken down by the bacteria and may be responsible for bad breath.

Bacteria can also live on the rough surface of your tongue. As well as brushing your teeth, cleaning your tongue can also help control bad breath.

You should have regular dental check-ups to ensure any oral hygiene problems are picked up and treated early. Your dentist will be able to advise you about how often you need a check-up.

Food and drink

Eating strongly flavoured foods, such as garlic, onions and spices, is likely to make your breath smell. Strong-smelling drinks, such as coffee and alcohol, can also cause bad breath.

Bad breath caused by food and drink is usually temporary. It can be avoided by not eating or drinking these types of food and drink too often. Good dental hygiene will also help.

Smoking

Smoking is another cause of bad breath. As well as making your breath smell, smoking stains your teeth, irritates your gums, and reduces your sense of taste. 

It can also significantly affect the development of gum disease, another major cause of bad breath. Stopping smoking will lower your risk of gum disease and help prevent bad breath.

Crash dieting

Crash dieting, fasting, and low-carbohydrate diets are another possible cause of bad breath. They cause the body to break down fat, which produces chemicals called ketones that can be smelled on your breath.

Medication

Some types of medication can also cause bad breath. These include:

• nitrates – these are sometimes used to treat angina, chest pain caused by a restriction in the blood supply to the heart
• some chemotherapy medication
• tranquillisers (phenothiazines)

If the medication you're taking is causing bad breath, your GP may be able to recommend an alternative.

Medical conditions

In rare cases, bad breath can be caused by certain medical conditions. In dry mouth (xerostomia), the flow and composition of saliva may be affected.

A lack of saliva can cause more bacteria than normal to build up in your mouth, as well as a change in the types of bacteria. A build-up of these in the mouth may lead to bad breath.

Dry mouth can sometimes be caused by a problem in the salivary glands or by breathing through your mouth instead of your nose.

In some cases, gastrointestinal conditions can also cause bad breath. For example, a bacterial infection of the stomach lining and small intestine (H. pylori infection) and gastro-oesophageal reflux disease (GORD) have been linked to bad breath.

If a gastrointestinal condition is thought to be causing your bad breath, you may need to have an endoscopy. This is a procedure where a piece of equipment called an endoscope is used to examine an area inside the body, such as your airways or abdomen.

Other medical conditions that can cause bad breath include diabetes and lung, throat, or nose infections – for example, bronchiectasis, bronchitis, tonsillitis, and sinusitis.

Treatment for bad breath (halitosis) will depend on its cause.

Usually, the most effective treatment is improving your dental hygiene. As part of your daily routine, you should:

• floss between your teeth
• brush your teeth and gums
• clean your tongue

You may want to consider investing in an electric toothbrush, which can make cleaning easier and more effective. 

Cleaning your teeth

Your dentist will probably recommend that you brush your teeth at least twice a day using fluoride toothpaste.

Below are some tips on how to brush your teeth and keep your mouth healthy. You should:

• use dental floss to clean between your teeth and remove trapped food that could cause tooth decay – brushing on its own only cleans about 60% of the tooth's surface
• choose a small or medium-sized toothbrush with soft, multi-tufted synthetic bristles
• replace your toothbrush every three to four months
• brush your teeth for at least two minutes – you could keep a toothbrush at work or school so you can brush your teeth after lunch
• brush all areas of your teeth, paying particular attention to where your teeth and gums meet – your dentist or oral hygienist may recommend using a special single-tufted brush for specific problem areas of your mouth
• use a separate toothbrush or a tongue scraper to lightly brush your tongue – some toothbrushes have a tongue cleaner on the back of the brush head
• avoid brushing your teeth for 30 minutes after drinking an acidic drink, such as fruit juice, or eating acidic fruit, such as oranges, to help prevent tooth abrasion

Your dentist may recommend that you rinse your mouth daily using an antibacterial or anti-odour mouthwash. This shouldn't replace brushing, but can be included as part of your daily routine.

Read more about dental health and how to keep your teeth clean.

Cleaning dentures

If you wear dentures, you should take them out at night to give your mouth a chance to rest. Clean your dentures thoroughly before putting them in the next morning:

• don't use toothpaste to clean your dentures as it can scratch the surface and cause stains
• clean your dentures thoroughly using soap and lukewarm water, denture cream, or a denture-cleaning tablet
• use a separate toothbrush to clean your dentures

Your dentures should stay clean and fresh if you follow this routine. It will also help prevent the build-up of plaque, which can cause bad breath.

Fresh breath tips

To help keep your breath fresh, you should:

• give up smoking
• eat a healthy, balanced diet and avoid eating strongly flavoured or spicy food
• cut down on sugary food and drink as it can increase the amount of bacteria in your mouth
• reduce your alcohol consumption 
• cut down on coffee
• drink plenty of water to help prevent your mouth becoming dry
• chew sugar-free gum after eating to stimulate the flow of saliva – this will help clean away any remaining food particles

You should visit your dentist for regular check-ups. Having regular dental check-ups will ensure any plaque and calculus – previously known as tartar – is removed from your teeth, particularly in areas that are difficult to reach.

Your dentist can recommend the best way to clean your teeth and gums, and point out areas you might be missing. They can also identify any signs of gum disease and ensure early treatment.

Gastrointestinal problems

Bad breath can be caused by a gastrointestinal problem, such as an H. pylori infection or gastro-oesophageal reflux disease (GORD). You may be referred to a gastroenterologist.

The treatment recommended will depend on the type of gastrointestinal condition you have. For example, if you have a stomach ulcer, you may need a combination of two or three different antibiotics and a proton pump inhibitor (PPI). This is known as eradication therapy.