# Bad breath

> What usually causes bad breath, from plaque and the tongue to a dry mouth and fasting, what helps at home, what mouthwash can do and when to see a dentist.

Source: https://www.nazemalioussef.com/en/patient-guides/bad-breath/  
Updated: 2026-09-28

Patient guide

Bad breath is very common, and most of the time it starts in the mouth itself, with bacteria on the teeth, along the gums and on the tongue. Dealing with it begins with cleaning at home. When it lasts despite careful cleaning, a dentist, and sometimes a doctor, can look for the cause.

From the professional website of Dr Nazem Al Ioussef Published 28 September 2026 Last reviewed 28 September 2026

## Where bad breath comes from

Hundreds of kinds of bacteria live naturally in the mouth. They feed on bits of food left behind and give off gases that smell. When bad breath is persistent, these bacteria are usually the source: they coat the teeth, collect along the gum line and settle on the tongue. The Oral Health Foundation estimates that around one in four people have bad breath regularly.

Food caught between the teeth, where a toothbrush does not reach, starts to rot. The tongue can hold a coating of bacteria, food debris and dead cells, especially towards the back. Brushing the teeth reaches neither place well, which is why cleaning between the teeth and cleaning the tongue matter.

### How food and plaque between the teeth cause bad breath

1. **Trapped.** Plaque and bits of food collect between two teeth and along the gum line, where bacteria break them down into gases that smell.
2. **Cleaned.** An interdental brush clears the gap between the teeth, which a toothbrush cannot reach.

Simplified drawing, not to scale.

## Common causes

- plaque and food left on and between the teeth, and on the tongue;
- strong-smelling or spicy food and drink, such as garlic, onions, spices and coffee;
- smoking and other tobacco use, which also dulls the sense of smell, so smokers may not notice their own breath;
- drinking a lot of alcohol;
- a dry mouth, explained below;
- fasting or crash dieting;
- [gum disease](https://www.nazemalioussef.com/en/patient-guides/gum-disease/), of which bad breath or a bad taste that will not go away can be a sign;
- [tooth decay](https://www.nazemalioussef.com/en/patient-guides/tooth-decay/), or an infection in a tooth or the gum;
- dentures that are not kept clean or are left in at night.

## A dry mouth, on waking and while fasting

Saliva rinses the mouth all the time. When too little of it flows, food and bacteria stay where they are and breath tends to smell more. The mouth can become dry from not drinking enough or from sweating a lot, which happens easily in hot weather. Some medicines dry it, and their leaflet lists this as a side effect. Breathing through the mouth at night, for example with a blocked nose, dries it too. Less saliva flows during sleep, which is one reason breath is often stale on waking.

The NHS lists fasting among the causes of bad breath. During a daytime fast, as in Ramadan, the mouth goes many hours without food or water and can become dry. Outside the fasting hours the usual routine still applies: brush and clean between the teeth and the tongue after suhoor and before sleep, and drink water regularly between iftar and suhoor.

## What helps at home

For most people, dealing with bad breath starts with keeping the mouth clean. The guide to [cleaning your teeth](https://www.nazemalioussef.com/en/patient-guides/cleaning-your-teeth/) explains the technique; these are the parts that matter most for breath.

1. **Brush twice a day.** Brush for about two minutes with a fluoride toothpaste, last thing at night and at one other time in the day. Be gentle: the NHS advises against brushing so hard that the gums or tongue bleed.
2. **Clean between the teeth every day.** Use interdental brushes or floss once a day to clear the plaque and food that a toothbrush leaves behind.
3. **Clean the tongue once a day.** Use a tongue cleaner (scraper) or your toothbrush, going gently from the back of the tongue towards the tip. It adds to brushing and cleaning between the teeth; it does not replace them.
4. **Keep the mouth moist.** Drink water regularly. Chewing gum that contains no sugar, or crunchy food such as carrots or apples, helps saliva flow. Mints or gum without sugar can also help after strong-smelling food and drink.
5. **Look after dentures.** Take removable dentures out at night and clean them thoroughly before wearing them again.
6. **Do not smoke, and keep alcohol and sugar down.** Stopping smoking helps the breath as well as the gums. Avoid drinking a lot of alcohol, and cut down on sugary food and drinks.

## Mouthwash

Mouthwash can freshen the breath for a while. Some kinds kill bacteria and others mask the smell, but the effect is temporary, and mouthwash will not fix a problem that has another cause, such as gum disease. The NHS suggests trying an antibacterial mouthwash or toothpaste, and a mouthwash without alcohol if your mouth is dry. If you find you need mouthwash all the time, the Oral Health Foundation suggests mentioning it to your dental team.

## When to see a dentist

See a dentist if:

- bad breath has not gone away after a few weeks of careful cleaning at home;
- your gums are painful, bleeding or swollen;
- you have toothache, or an adult tooth feels loose;
- a bad taste in your mouth does not go away;
- your dentures are causing problems.

The dentist looks for a cause in the mouth, such as gum disease, decay, an infection or a dry mouth, and at how the teeth, gums and tongue are being cleaned. Swelling of the face or gum with pain can mean an infection that needs prompt care; the guide to [dental emergencies](https://www.nazemalioussef.com/en/patient-guides/dental-emergencies/) explains when it is urgent.

## When it may come from elsewhere

Less often, bad breath comes from outside the mouth: tonsillitis and other throat infections, sinus problems, chest infections, acid reflux, diabetes, or liver or kidney disease. If a dentist finds nothing in the mouth to explain it, they may suggest seeing a doctor.

See a doctor if bad breath comes with symptoms elsewhere, such as a sore throat, a blocked nose or heartburn, or if a dry mouth comes with passing urine more often or dry eyes.

## Questions patients ask

**How can I tell if I have bad breath?**

It is hard to judge your own breath. A strange taste in the mouth can be a sign. The Oral Health Foundation suggests licking the inside of your wrist, waiting a few seconds and then smelling it, or asking someone you trust to tell you honestly.

**Does mouthwash get rid of bad breath?**

Not on its own. It freshens the breath for a while, but it does not remove plaque between the teeth or the coating on the tongue, and it does not treat gum disease or any other cause.

**Can medicines cause bad breath?**

Some can, by drying the mouth. The leaflet that comes with a medicine lists dry mouth if it is a known side effect. Do not stop a prescribed medicine on your own: ask the doctor who prescribed it or a pharmacist, who can also suggest products that keep the mouth moist.

**Do I need a tongue scraper?**

Not necessarily. The Oral Health Foundation suggests a tongue cleaner made for the purpose, but a toothbrush also works. If you gag, start in the middle of the tongue and move further back over time, breathing out slowly while you clean.

**Is bad breath a sign of something serious?**

Usually not. Most bad breath comes from the mouth, and better cleaning is where to start. If it lasts for weeks despite careful cleaning, or comes with bleeding gums, pain or loose teeth, see a dentist. If the mouth is healthy, the dentist may suggest seeing a doctor.

## What this page rests on

This guide rests on patient information from the NHS, the Oral Health Foundation and the American Dental Association. It is general information: the cause of bad breath in a particular person can only be found by a dentist or doctor who examines them.

General health information, not a diagnosis or a treatment recommendation for any individual.

### Sources

1. NHS — [Bad breath](https://www.nhs.uk/symptoms/bad-breath/)
2. Oral Health Foundation — [Bad breath](https://www.dentalhealth.org/bad-breath)
3. American Dental Association, MouthHealthy — [Bad breath](https://www.mouthhealthy.org/all-topics-a-z/bad-breath)
4. NHS — [Dry mouth](https://www.nhs.uk/symptoms/dry-mouth/)
5. Oral Health Foundation — [Cleaning your tongue](https://www.dentalhealth.org/cleaning-your-tongue)

## Related pages

- [Teeth grindingGrinding and clenching, often at night: the signs, the causes and what can help.](https://www.nazemalioussef.com/en/patient-guides/teeth-grinding/)
- [Mouth ulcersWhy mouth ulcers appear, how to ease them, and when one needs checking.](https://www.nazemalioussef.com/en/patient-guides/mouth-ulcers/)
- [Cleaning your teeth properlyBrushing, toothpaste and cleaning between the teeth: daily habits that protect teeth and gums.](https://www.nazemalioussef.com/en/patient-guides/cleaning-your-teeth/)