Occasional or temporary halitosis has several causes, including smoking, eating strongly flavoured foods including garlic and spices. Coffee and alcohol can also result in bad breath.
Diets, especially low-carb, high-protein diets, cause bad breath. This is because they stimulate your body to break down fat, producing chemicals called ketones that can smell unpleasant.
Some medicines cause halitosis, including nitrates used to treat angina, some chemotherapy drugs, tricyclic antidepressants, melatonin and nicotine lozenges.
Medical conditions can be another cause, most commonly dry mouth (xerostomia). This reduces saliva in your mouth, leading to a build-up of bacteria. Nasal problems such as sinusitis or polyps also cause bad breath and a gastrointestinal infection called H. pylori (which can also cause peptic ulcers) is another cause of halitosis.
The most common reason for persistent halitosis is poor dental care. When teeth are not properly cleaned, bacteria break down food and debris trapped between your teeth and produce the smelly gases responsible for halitosis. In more serious cases this leads to gum disease, which also causes bad breath. Bacteria also build up on your tongue, and it’s thought brushing your tongue regularly helps to control bad breath.
A simple way to check whether you have smelly breath is to lick the inside of your wrist, wait a few seconds for the saliva to dry, then sniff your wrist. If it smells unpleasant then you probably have a bad breath problem. Ask a trusted family member or friend to smell your breath for you and tell you honestly if it smells unpleasant.
If you are worried or embarrassed about halitosis and want to find out the cause, see your dentist or GP. Ideally, avoid spicy or strong-smelling foods or drinks for 48 hours before and don’t smoke for 24 hours before the consultation.
Your dentist or GP will ask you to breathe out through your mouth, then through your nose to locate where the halitosis is coming from.
Your mouth will be examined and you'll be asked about your diet and lifestyle, medical conditions and medication to work out the cause.
Who gets it?
About one in four people are estimated to suffer from persistent bad breath. However, almost everyone will have it at some time, especially in the mornings or after eating garlic or a curry. Around 80 to 90 per cent of cases of persistent halitosis are caused by a problem inside your mouth.
The main treatment for halitosis is a regular and thorough daily dental care routine. Brush your teeth twice daily using a fluoride paste, spending at least two minutes each time.
Clean between your teeth every day – regular brushing only cleans 60 per cent of the surface of your teeth - using dental floss, tape or an inter-dental brush to clear food from gaps between your teeth. It’s also a good idea to choose a toothpaste that also contains an anti-bacterial agent, such as triclosan.
Try using a mouthwash daily, to kill bacteria and neutralise chemicals that cause halitosis. Look for ingredients including chlorhexidine, cetylpyridinium chloride, chlorine dioxide, zinc chloride and triclosan. A trial using a CB12 mouthwash (zinc acetate and chlorhexidine) found it gave 12-hour relief from halitosis.
Mouthwashes containing alcohol can have a drying effect on your mouth, so buy an alcohol-free one. Cleaning the back of your tongue each day to remove bacteria can help. Use either a soft toothbrush or a plastic tongue scraper.
Chewing sugar-free gum after eating increases saliva flow, which may help your mouth to flush out food particles.
Research is ongoing into whether probiotic bacteria can help improve dental health and prevent bad breath.