Mouth

Persistent bad breath

An unpleasant smell from the mouth that does not clear with brushing — most often caused by oral hygiene problems, gum disease or a dry mouth, but occasionally a sign of a sinus, throat or, rarely, a serious metabolic problem.

Education and reference only. This explains the common causes of persistent bad breath and the warning signs that need urgent help, in plain language — it is not a diagnosis or a substitute for advice from a clinician. If you feel very unwell or are worried, seek medical help.

Written by Meds Global Health Clinical Team · Clinically reviewed by Dr Muhammad Suffyan, MB BS, Founder & Clinical Director · Last reviewed · How we review

Quick answer

What is persistent bad breath?

Persistent bad breath, or halitosis, is a long-standing unpleasant smell from the mouth that goes beyond the temporary odour of garlic, coffee or a morning before brushing. By far the commonest source is the mouth itself: bacteria coating the tongue, food trapped between the teeth, gum disease, dental decay and a dry mouth all generate smelly compounds.

  • Get urgent help: Call 999 if the breath smells sweet or fruity and the person is very thirsty, drowsy, breathing deeply and rapidly or vomiting — especially a child or young adult — as this can mean diabetic ketoacidosis. Seek urgent help for bad breath with a severe sore throat, drooling, difficulty swallowing or breathing, or a hot, swollen face.
  • Self-care: Good oral hygiene resolves most persistent bad breath.

About persistent bad breath

Persistent bad breath, or halitosis, is a long-standing unpleasant smell from the mouth that goes beyond the temporary odour of garlic, coffee or a morning before brushing. By far the commonest source is the mouth itself: bacteria coating the tongue, food trapped between the teeth, gum disease, dental decay and a dry mouth all generate smelly compounds. Beyond the mouth, infections in the sinuses, tonsils or throat, and acid reflux washing stomach contents up the food pipe, can give the breath a foul or sour smell. Smoking and a dry mouth from medication, mouth-breathing or dehydration make it worse. Very occasionally the breath carries a clue to a problem elsewhere in the body — most importantly a sweet or fruity smell that can accompany dangerously high blood sugar. Most bad breath, however, improves greatly with good oral hygiene and a dental check.

When to get help

Call 999 now if…

Call 999 or go to A&E if persistent bad breath comes with any of these warning signs:

  • Call 999 if the breath smells sweet or fruity and the person is very thirsty, drowsy, breathing deeply and rapidly or vomiting — especially a child or young adult — as this can mean diabetic ketoacidosis.
  • Seek urgent help for bad breath with a severe sore throat, drooling, difficulty swallowing or breathing, or a hot, swollen face.
  • Seek prompt assessment for persistent bad breath with bleeding, loose teeth or painful, swollen gums.
  • Arrange review for bad breath with unexplained weight loss, a persistent mouth ulcer or a lump in the mouth or throat lasting more than three weeks.
  • Seek urgent help for foul breath with a high fever and feeling very unwell.

When to see a doctor

Most bad breath is improved by better oral hygiene, more fluids and a dental check-up, so start there. See a dentist if bad breath persists despite good mouth care, or if you have bleeding, swollen gums, loose teeth or dental pain. Speak to a doctor if the smell seems to come from the sinuses, throat or stomach, or if it comes with other symptoms such as reflux, a chronic blocked nose or recurrent tonsil infections. Treat a sweet, fruity smell on the breath with thirst, drowsiness and rapid breathing as an emergency, and seek prompt review for any persistent mouth ulcer, lump or unexplained weight loss.

999Emergency — call 999 or go to A&E
111Urgent advice — call NHS 111 or use 111 online
GPNon-urgent — see your GP or pharmacist

Not sure how urgent it is? It is always OK to call NHS 111 for advice, day or night.

What can cause it

Common causes of persistent bad breath

Persistent bad breath has many possible causes. Each links to a full, plain-language guide to that condition — what it is, how it's treated and when to seek help.

Acid reflux & GORD Digestive Acid and stomach contents rising into the food pipe can give the breath a sour or unpleasant smell, often with heartburn. Sinusitis Ear, nose and throat Infected, blocked sinuses drip mucus down the back of the throat, which bacteria break down into a foul-smelling odour. Tonsillitis Infections Infected tonsils, and debris trapped in the tonsil crypts, produce a marked bad smell along with a sore throat. Oral thrush Ear, nose and throat A fungal infection coating the mouth can cause an unpleasant taste and smell, often with white patches and soreness. Type 1 diabetes Endocrine Very high blood sugar can make the body produce ketones, giving the breath a distinctive sweet or fruity smell. Type 2 diabetes Endocrine Poorly controlled blood sugar can contribute to a dry mouth and gum problems that worsen breath odour.

What helps

Self-care and what you can do

Good oral hygiene resolves most persistent bad breath. Brush your teeth thoroughly twice a day and clean between them daily with floss or interdental brushes, and gently clean your tongue, where odour-causing bacteria collect. Stay well hydrated to counter a dry mouth, and chew sugar-free gum to keep saliva flowing. Cutting down on smoking, alcohol and strong-smelling foods makes a clear difference, and keeping up regular dental check-ups lets problems such as gum disease and decay be caught early. If you wear dentures, clean them every day and leave them out overnight as advised. If careful hygiene does not solve the problem, see a dentist or doctor, because the cause may lie beyond simple oral care.

Answers

Persistent bad breath: frequently asked questions

What causes persistent bad breath?

Most persistent bad breath comes from the mouth — bacteria on the tongue, food trapped between teeth, gum disease, decay and a dry mouth. Less often it comes from the sinuses, tonsils, throat or acid reflux. Good oral hygiene and a dental check usually identify and improve it.

Can a dry mouth make my breath smell?

Yes. Saliva washes away food debris and bacteria, so a dry mouth from dehydration, mouth-breathing, smoking or certain medicines lets odour-causing bacteria build up. Drinking enough fluids and keeping saliva flowing helps.

Is bad breath ever a sign of something serious?

Rarely. A sweet or fruity smell with thirst, drowsiness and rapid breathing can signal dangerously high blood sugar and needs emergency help. Persistent bad breath with a non-healing mouth ulcer, a lump or unexplained weight loss should also be reviewed promptly.

Will mouthwash cure bad breath?

Mouthwash may mask the smell for a short time but does not treat the cause. Thorough brushing, cleaning between the teeth, cleaning the tongue, staying hydrated and regular dental check-ups are far more effective, and underlying problems still need addressing.

Sources

Where this is drawn from

  • NICE CKS: Halitosis.
  • Oral Health Foundation: bad breath.

Related symptoms

Dry mouthA persistent feeling that the mouth is dry and short of saliva — often a side effect of me…Mouth ulcersPainful sores on the lining of the mouth, lips or tongue that are usually harmless and hea…Sore throatPain, scratchiness or rawness at the back of the throat that is usually caused by a passin…HeartburnHeartburn is a burning feeling in the chest caused by stomach acid rising into the gullet,…Difficulty swallowingTrouble getting food or drink to go down, or a sense that it sticks or is painful on the w…

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