Bad breath (halitosis) explained

What causes bad breath

Most bad breath starts in the mouth. Bits of food and bacteria build up on the teeth, gums, and especially the tongue, and as bacteria break down food particles they release unpleasant-smelling gases. Poor oral hygiene, so that plaque and food are not removed properly, is the most common cause. Gum disease and tooth decay can also cause a persistent smell, as can a dry mouth, because saliva normally helps wash bacteria away. Strong foods such as garlic, onions, and spices, along with smoking and drinking a lot of alcohol or coffee, contribute too. Crash dieting and fasting can produce a distinctive breath smell as the body burns fat. Less often, bad breath comes from problems elsewhere, such as infections in the nose, throat, or sinuses, or certain medical conditions. Identifying the likely cause is the first step to fixing it.

Good oral hygiene comes first

Because most bad breath comes from the mouth, good oral hygiene is the mainstay of keeping breath fresh. Brush your teeth twice a day with fluoride toothpaste, including last thing at night, and clean between your teeth daily with floss or interdental brushes to remove trapped food and plaque. Gently cleaning your tongue, where a lot of odour-causing bacteria collect, can make a noticeable difference. Drinking water and keeping your mouth from getting too dry also helps. A pharmacist can advise on mouthwashes, though these mainly mask odour rather than treat its cause, so they work best alongside good brushing and flossing rather than instead of them. Keeping dentures clean and taking them out at night, if you wear them, is important too. Regular dental check-ups help spot and treat problems such as gum disease early.

Diet, smoking and lifestyle

What you eat, drink, and do affects how your breath smells. Strong-smelling foods such as garlic and onions can linger because their compounds are absorbed and released as you breathe out, so the effect passes only once they leave your system. Smoking is a major cause of bad breath and also stains teeth, dries the mouth, and raises the risk of gum disease, so stopping smoking helps in many ways. Alcohol and lots of coffee can dry the mouth and worsen odour. Sugary foods and drinks feed the bacteria that cause both decay and bad breath. Staying well hydrated keeps saliva flowing, which naturally cleans the mouth, and chewing sugar-free gum can help stimulate saliva after meals. Making these everyday adjustments, alongside good brushing, often improves breath and benefits your overall dental and general health.

When bad breath signals something else

Sometimes bad breath is linked to a health problem beyond routine oral care. Gum disease (gingivitis and its more advanced form) is a common dental cause and needs treatment to prevent it worsening. Infections or blockages in the nose, sinuses, throat, or tonsils can cause a persistent smell, and a very dry mouth from some medicines or conditions can contribute. Occasionally, ongoing bad breath is associated with problems such as acid reflux, poorly controlled diabetes, or other medical conditions. A distinctly sweet or fruity smell to the breath, particularly in someone with diabetes who is unwell, can be a warning sign that needs urgent medical attention. Most bad breath, though, is due to the mouth rather than a serious illness, so a dental review is usually the sensible first step before looking for less common causes.

When to see a dentist or GP

If bad breath persists despite good oral hygiene, the best first port of call is usually a dentist, who can check for gum disease, tooth decay, and other dental causes and treat them. Regular dental check-ups also help prevent these problems. See a GP if your dentist finds no dental cause and the problem continues, or if bad breath comes with other symptoms such as a sore throat, nasal congestion, heartburn, or feeling generally unwell, as these may point to another cause that needs assessment. If you have diabetes and notice a sweet or fruity smell to your breath together with feeling unwell, thirsty, or drowsy, seek medical help promptly, as this can be a sign that needs urgent attention. For most people, though, better oral care and a dental check are all that is needed to freshen the breath.