Menu

Mouth ulcer: how to ease the pain and help it heal

Reviewed by Dr Aaiman Liaqat✓, BDS

By 6 min readPublisher: Saadat Rafiq

Last updated: 2 November 2026References

Set preferred
Illustration of a woman at a bathroom mirror gently pulling down her lower lip, with a close-up circle showing a small round pale sore with a marigold ring inside the lipIllustration
On this page 11 sections

In short

Most mouth ulcers heal on their own in a week or 2. Use a soft toothbrush, avoid spicy, acidic and crunchy food, rinse with warm salt water, and ask a pharmacist for a gel or rinse. See a dentist if one hasn't healed after 2 weeks.

Jump to the steps

At a glance

Usually heals
In a week or 2 (NHS)
Contagious?
No (NHS, gesund.bund.de)
Ease it
Soft brush, soft food, cool drinks through a straw (NHS)
Rinse
Half a teaspoon of salt in a glass of warm water (NHS)
Pharmacist
Gels, rinses or sprays without a prescription (NHS)
Get it checked
Not healed after 2 weeks (gesund.bund.de, MedlinePlus); always after 3 weeks (NHS)
Checked
November 2026

A mouth ulcer is a small, painful sore inside the cheek or lip. There's no quick fix, but avoiding what irritates it helps it heal faster, hurt less and come back less often (NHS). Advice on when to get it checked differs between countries, so the table near the end shows the UK, Germany and the US side by side.

See a dentist if an ulcer hasn't healed after 2 weeks (gesund.bund.de, MedlinePlus). See a dentist or GP if it lasts longer than 3 weeks, is bigger than usual or near the back of your throat, or bleeds or gets more painful and red (NHS). See a GP if you also have ulcers elsewhere on your body or painful, swollen joints (NHS).

What do you want to do?

Check what it is

Round, pale, inside the mouth. Start at Check it's an ulcer.

Make it hurt less

Soft food, salt rinse, pharmacist. Go to Ease the pain.

It won't go away

Know when to get it checked. Go to See a dentist or GP.

Check it's a mouth ulcer

  1. Look for a small round sore inside your cheek or lip.

    Illustration of a close-up of a lower lip gently pulled down, showing one small round pale sore with a marigold ring on the inside
    Illustration

    Mouth ulcers usually appear inside the cheeks or lips, and sometimes on the tongue (NHS). They are round and white or yellow with a red edge, and usually only a few millimetres across (gesund.bund.de, MedlinePlus). You can have more than one at a time (NHS).

  2. Make sure it isn't a cold sore.

    Illustration of two lip close-ups side by side: a round pale sore inside the lip with a green tick, and a cluster of tiny bumps on the outside edge of the lip
    Illustration

    Cold sores appear on the lips or around the mouth, and often start with tingling, itching or burning (NHS). Mouth ulcers are inside the mouth.

  3. Carry on as normal: ulcers aren't catching.

    Illustration of a woman sitting at a table chatting with a friend over two cups
    Illustration

    Mouth ulcers are not contagious (NHS, gesund.bund.de).

Ease the pain while it heals

  1. Brush gently with a soft toothbrush.

    Illustration of a woman at the basin brushing her teeth slowly with a soft toothbrush, with a small gentle arrow
    Illustration

    Use a soft-bristled toothbrush (NHS). Brushing too roughly can bring on ulcers (MedlinePlus).

  2. Skip spicy, salty, acidic and crunchy food.

    Illustration of a slice of toast, a bag of crisps, a chilli and a lemon crossed out, next to a bowl of soft porridge with a green tick
    Illustration

    Avoid very spicy, salty or acidic food, and rough, crunchy food such as toast or crisps (NHS). gesund.bund.de names bread-roll crusts, sour fruit and hot spices. Eat softer foods instead (NHS).

  3. Drink cool drinks through a straw.

    Illustration of a woman sipping a cool drink through a straw, with a steaming mug and a glass of orange juice crossed out on the table
    Illustration

    Drink cool drinks through a straw, and avoid very hot or acidic drinks such as fruit juice (NHS).

  4. Rinse with warm salt water, then spit it out.

    Illustration in two panels: a hand stirring half a teaspoon of salt into a glass of warm water, then a woman spitting the rinse into a bowl
    Illustration

    Dissolve half a teaspoon of salt in a glass of warm water, rinse your mouth, then spit it out. Don't swallow it. You can repeat this as often as you like (NHS). MedlinePlus also suggests salt water, and says to avoid mouthwashes with alcohol, which can irritate the sore.

  5. Check your toothpaste for sodium lauryl sulphate.

    Illustration of a hand turning a toothpaste tube round to read the back, with a magnifying glass over a blank label
    Illustration

    The NHS says not to use toothpaste that contains sodium lauryl sulphate while you have an ulcer. Check the ingredients list on the tube.

  6. Ask a pharmacist for a gel, rinse or spray.

    Illustration of a woman at a pharmacy counter while the pharmacist hands her a small plain tube
    Illustration

    A pharmacist can recommend something to speed up healing, prevent infection or ease the pain, such as a mouthwash, gel, spray or lozenges, without a prescription (NHS). gesund.bund.de says gels, creams and mouth rinses can ease the pain.

Stop the cause

  1. Get anything sharp or rubbing fixed by your dentist.

    Illustration in two panels: a tooth with a jagged edge rubbing a sore spot on the cheek, then an arrow to the same tooth smoothed with a green tick
    Illustration

    Badly fitting dentures, braces, rough fillings or a sharp tooth can cause ulcers (NHS). Your dentist can sort these out.

  2. Take care not to bite your cheek.

    Illustration of a woman eating slowly with small bites from a fork at the table
    Illustration

    Biting the inside of your cheek, and cuts or burns from hard food or hot drinks, are common causes (NHS). Eating slowly can help you avoid them.

  3. Eat a balanced diet and get some rest.

    Illustration in two panels: a plate of balanced food, then a woman sleeping peacefully in bed
    Illustration

    Eat a healthy, balanced diet (NHS). Feeling tired, stressed or anxious can bring on ulcers, and so can a shortage of iron, zinc, folic acid, vitamin B or vitamin D (NHS). A sore, red tongue with mouth ulcers can be a sign of vitamin B12 deficiency, which a GP can check with a blood test (NHS). gesund.bund.de also names stress and iron or vitamin B shortage.

See a dentist or GP

  1. Get it checked if it hasn't healed in 2 weeks.

    Illustration of a wall calendar with three rows of ticked squares, and an arrow to a woman phoning to book an appointment
    Illustration

    In Germany, gesund.bund.de suggests a dentist or ear, nose and throat (HNO) practice if an ulcer hasn't healed within 2 weeks, and MedlinePlus says contact your provider if it hasn't gone after 2 weeks of home care. The NHS gives 3 weeks as the point where every lasting ulcer needs a GP or dentist, because a long-lasting ulcer is sometimes a sign of mouth cancer. So book a dentist at 2 weeks, and don't wait past 3. It helps to keep a note of when it started.

  2. Go sooner if it's unusual, or you have other symptoms.

    Illustration of a doctor gently looking into a woman's mouth with a small torch
    Illustration

    See a dentist or GP if the ulcer is bigger than usual, near the back of your throat, bleeds, or gets more painful and red, which can be infection (NHS). See a GP if you have ulcers elsewhere on your body or painful, swollen joints (NHS), or fever, diarrhoea, headache or a rash (MedlinePlus). If you get ulcers more than 2 or 3 times a year, tell your doctor (MedlinePlus).

What each country says

UKGermanyUS
How long it lastsA week or 2 (NHS)About a week; large ones up to 4 weeks (gesund.bund.de)Pain 7 to 10 days; healed in 1 to 3 weeks (MedlinePlus)
First helpPharmacist: gels, rinses, sprays, lozenges, salt rinse (NHS)Pain-relieving gels, creams or mouth rinses (gesund.bund.de)Salt water or mild, alcohol-free mouthwash (MedlinePlus)
Get it checked after3 weeks (NHS)2 weeks (gesund.bund.de)2 weeks of home care (MedlinePlus)
Who to seeDentist or GP (NHS)Dentist or ear, nose and throat (HNO) doctor (gesund.bund.de)Your health care provider (MedlinePlus)
Keeps coming backTriggers include stress, hormone changes and vitamin shortages (NHS)Common; cause unknown (gesund.bund.de)Tell your provider if more than 2 or 3 times a year (MedlinePlus)

How to tell it's healing

  • The pain eases after a few days (gesund.bund.de, MedlinePlus).
  • The sore turns greyish as it heals (MedlinePlus).
  • It's gone within a week or 2 (NHS).

If something isn't right

What happensWhat it meansWhat to do
Not healed after 2 weeksIt needs checkingSee a dentist (gesund.bund.de, MedlinePlus); don't wait past 3 weeks (NHS)
It bleeds, or gets bigger, redder or more painfulIt may be infectedSee a dentist or GP (NHS)
Small sores on the outside of the lip that tingled firstProbably a cold sore, not an ulcerAsk a pharmacist (NHS)
A denture, brace or sharp tooth keeps rubbingThe same spot keeps getting hurtSee your dentist (NHS)
Ulcers come with a fever, rash or sore jointsThere may be another causeSee a GP (NHS, MedlinePlus)

Tooth pain too? See our guide to toothache until you can see a dentist.

Questions readers ask

How long does a mouth ulcer last?

Usually a week or 2 (NHS). gesund.bund.de says most are gone after about a week, but large ones can take up to 4 weeks. MedlinePlus says the pain often goes in 7 to 10 days and healing can take 1 to 3 weeks.

Are mouth ulcers contagious?

No. The NHS and gesund.bund.de both say mouth ulcers are not contagious. Don't confuse them with cold sores, which are on or around the lips (NHS).

Can a mouth ulcer be cancer?

Rarely. Most are harmless, but a mouth ulcer that lasts a long time is sometimes a sign of mouth cancer, so get one checked by a dentist if it hasn't healed after 2 weeks (gesund.bund.de, MedlinePlus), and always if it lasts longer than 3 weeks (NHS). Ordinary ulcers don't turn into cancer (MedlinePlus).

Why do I keep getting them?

Often nobody knows. gesund.bund.de says the cause is unknown, and genes, stress, a weak immune system or hormone changes may play a part. The NHS adds feeling tired or stressed, shortages of vitamins such as vitamin B12, and some medicines; a sore, red tongue with mouth ulcers can be a sign of vitamin B12 deficiency (NHS). See your GP or provider if you get them more than 2 or 3 times a year (MedlinePlus).

What if I have lots of ulcers at once?

Several ulcers can be a sign of another condition, such as hand, foot and mouth disease, which also causes a rash on the hands and feet (NHS). See a GP.

Does salt water help?

It can. The NHS lists a salt mouthwash among the things a pharmacist may suggest: half a teaspoon of salt in a glass of warm water, rinse, then spit it out. MedlinePlus also suggests rinsing with salt water.

Did this solve the problem?

What did you think?

Reaction counts are loading.

Spotted a mistake? If a step is unclear or a picture is inaccurate, tell us the step number and what needs correcting. Email us about this page or use the contact form. We read every report, and fixes are listed on What changed.

Liked this article?

Follow us for new articles and short how-to videos.

Subscribe on YouTubeFollow on InstagramFollow on FacebookFollow on XFollow on ThreadsFollow on Pinterest