Bad Breath: Causes and How It Is Treated
For anyone concerned about bad breath (halitosis): causes, self-checks, treatment, mouthwash, mints and when to see a dentist. In a large bad breath clinic study, most cases started in the mouth, mainly from tongue coating or gum disease. The NHS says you can usually treat it yourself.
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Clinically reviewed by Dr Ibraheem Ijaz, dentist · GDC 301711
Medical disclaimer: This page is for general information only. It does not replace an examination or treatment by a dentist.
Dr Ibraheem Ijaz, GDC 301711, a General Dental Practitioner and the principal dentist at Deepcar Dental Care, reviewed this page. His qualifications include BDS, BSc (Hons) and MSc (Leeds).
Where does bad breath come from?
Bad breath mostly starts in the mouth, a Belgian study of 2,000 bad breath clinic patients found: 76% had an oral cause.
Tongue coating accounted for 43%, gum disease for 11% and both for 18%; 4% had ear, nose and throat or other causes outside the mouth, and 16% pseudo-halitosis or halitophobia. Still, the authors concluded, a team approach is needed to find these.
What causes bad breath in the mouth?
Persistent bad breath is usually caused by smelly gases from bacteria coating the teeth, gums and tongue, the Oral Health Foundation (OHF) says.
Food stuck between teeth can also rot, and the NHS lists gum disease, holes in the teeth and infection. A 2017 review of five cross-sectional studies found 3.16 times higher odds of bad breath with periodontitis, the advanced form of periodontal disease. A 2025 UAE study of 102 adults also linked it with periodontal pockets and decay, among other factors.
Why does tongue coating cause bad breath?
Tongue coating can cause bad breath because the tongue collects bacteria, food debris and dead cells, the OHF explains.
Clean gently from back to front, as an extra to brushing, the OHF advises. A 2019 Cochrane review of trials in adults with bad breath from oral causes, excluding advanced gum disease, rated the evidence for tongue cleaning, compared with none, very uncertain, with no side-effect data.
While cleaning your tongue, see your dentist or doctor if you notice ongoing soreness or pain, patches that do not rub off, or lumps, ulcers or colour changes, the OHF advises.
How does a dry mouth cause bad breath?
Without enough saliva, you may be more likely to have bad breath, the OHF says.
The NHS gives the main causes as dehydration, medicines, breathing through your mouth at night, anxiety, cancer treatment and oral thrush. Do not stop taking a prescribed medicine without getting medical advice first, the NHS adds.
NHS guidance says to see a GP if you have a dry mouth and it makes it difficult when talking or eating, your mouth is still dry after trying home or pharmacy treatments for a few weeks, you are struggling to eat regularly, you have problems with your sense of taste that are not going away, your mouth is painful, red, swollen or bleeding, you have sore white patches in your mouth, you think a prescribed medicine might be causing it, or you have other symptoms, like needing to pee a lot or dry eyes.
When is the cause not in the mouth?
Causes outside the mouth are less common: 4% in a Belgian bad breath clinic study.
The NHS lists conditions like tonsillitis and acid reflux. The OHF adds sinus problems, throat or chest infections, diabetes, and liver or kidney problems, and says that if your dentist cannot find a problem with your mouth, they might ask you to see your doctor.
Can bad breath come from the stomach?
Sometimes. The NHS lists bad breath as a possible acid reflux symptom, and a 2026 review of 24 studies found an observational link, not proof of cause, with the stomach bacterium Helicobacter pylori.
NHS guidance says to see a GP if lifestyle changes and pharmacy medicines are not helping your heartburn, you have heartburn most days, or you also have other symptoms, like food getting stuck in your throat, frequently being sick, or losing weight for no reason. If at any time your symptoms get worse, contact a GP, go to 111.nhs.uk or call 111.
To ask about bad breath, book online or call 0114 288 2121.
How can you check your own breath?
There's a quick test you can try, the OHF says, though it can be hard to tell.
- Lick the inside of your wrist, wait a few seconds, then smell it; if it smells bad, your breath probably does too (OHF).
- Ask someone you trust to tell you honestly, and notice any strange taste (OHF).
Self-checks are only a guide. The NHS also lists strong-smelling or spicy food and drink, smoking, and fasting or crash dieting as causes.
How is bad breath treated?
You can usually get rid of bad breath by keeping your mouth clean, the OHF says.
For brushing and cleaning between the teeth, browse this section on preventing gum disease.
Gum disease needs checking by a dentist, the NHS says, and our periodontitis page explains how its advanced form is treated.
Cochrane's 2019 review of 44 adult trials of bad breath from oral causes, excluding advanced gum disease and mostly one to four weeks long, found only low- to very low-certainty evidence for the treatments tested and could not say whether one works better than another.
What can mouthwash and mints do?
Mouthwash can help freshen your breath but will not fix bad breath that has another cause, the OHF says.
The NHS suggests sugar-free mints or chewing gum after strong-smelling food and drinks, and trying an antibacterial mouthwash or toothpaste. The 2019 Cochrane review on halitosis left out advanced gum disease and products that only mask odour. For a chewing gum and two mouthwashes, single trials gave very uncertain or low-certainty evidence, with no side-effect data. When mouthwash helps and when it does not has its own page.
When should you see a dentist about bad breath?
NHS guidance gives these actions; if you do not have a dentist or cannot get an emergency appointment, call 111 or visit 111 online:
- Bad breath that does not go away after treating it yourself for a few weeks, painful, bleeding or swollen gums, toothache or wobbly adult teeth, or problems with your dentures: see a dentist.
- Gum disease with other symptoms such as very sore and swollen gums, teeth becoming loose or falling out, ulcers or red patches in your mouth, or a lump in your mouth or on your lip: ask for an urgent dentist appointment.
- Toothache that lasts more than 2 days, does not go away with painkillers, or comes with a high temperature, pain when you bite, red gums, a bad taste or a swollen cheek or jaw: see a dentist.
- Toothache with swelling around your eye or neck, or swelling in your mouth or neck that makes it difficult to breathe, swallow or speak: go to A&E, but do not drive; ask someone to drive you or call 999.
How much does a halitosis assessment cost?
A halitosis assessment, non-surgical periodontal therapy, treatment of advanced gum disease, gum surgery and gum grafting have no line on the current fee list. Neither do BPE screening or full six-point periodontal charting. Ask us about cost.
Frequently asked questions
What affects morning breath?
Low saliva and tongue coating may play a part. A 2025 cross-sectional study of 92 young adults found less saliva and more tongue coating in those reporting morning breath. Small studies of healthy volunteers found volatile sulphur compounds in breath highest on waking.
Can you have bad breath without knowing it?
Yes, and the reverse happens. In a 2025 UAE study, 26% of 102 adults reported bad breath on a questionnaire and 57.8% on a cupping-hands self-test, while a breath gas meter found it in 63.7%. In a German bad breath clinic, 72.1% of 407 people reporting it had detectable odour.
Can dentures affect your breath?
They may. NHS advice on bad breath is to keep dentures clean, remove them at night and see a dentist about denture problems. In a 2025 UAE study of 102 adults, wearing a dental prosthesis was independently linked with bad breath.
Do tonsil stones cause bad breath?
Occasionally. Tonsil stones, debris and bacteria collected in the tonsils, generally cause minimal symptoms but occasionally bad breath, NHS Lothian referral guidance says. If your dentist cannot find a problem with your mouth, the OHF says, they might ask you to see your doctor.
What hygiene and gum care is available at Deepcar Dental Care?
Hygiene and gum care at Deepcar Dental Care includes a halitosis assessment, BPE screening at every examination, full six-point periodontal charting and non-surgical periodontal therapy. Treatment of advanced gum disease (severe periodontitis) is done in house, as are gum surgery and gum grafting.
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Deepcar Dental Care is at 334 Manchester Road, Deepcar, Sheffield, S36 2RH, with free parking directly outside. See hygiene appointments and patient reviews.
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