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How to Treat a Mouth Ulcer or Canker Sore and Relieve Pain at Home

Amanda Napitu
Amanda Napitu
Medically reviewed by
Dr. Fanar Swaida
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A mouth ulcer, or canker sore, is usually nothing to worry about. They are often benign and disappear as easily as they appear but they can be very painful. They commonly develop inside the cheeks or lips, but you can also get a gum or tongue ulcer.

This is one of the oral health problems that few people have never experienced. But when mouth ulcers do appear, we often don't know what to do. Although they usually go away by themselves, there are various treatments and home remedies for mouth ulcers which help them clear up faster.

On rare occasions, a canker sore can signal a more serious health problem, so it's important to know the warning signs.

In this article we explain:

  • The different kinds of mouth sores
  • What causes them
  • What you can do to treat them
  • When you might need to see a doctor

What is a canker sore?

large ulcer on lips
Ulcers in the mouth can be very painful

Sores that appear on the inside of the mouth – including the tongue, cheeks, gums and roof of the mouth – are known as ‘canker sores' or ‘mouth ulcers'. These ulcerations are typically around 4mm in diameter. They have reddish edges and a yellow or light centre. One or more sores can develop at once.

Despite being so small, ulcers in the mouth – and particularly on the tongue – can be incredibly painful. Anyone can get them, and as many as one in five Brits regularly develop them. The good news is that they are usually nothing to worry about and they should clear up in a week or two without any medical intervention. The pain they cause normally lasts for just a couple of days.

Although you don't need to do anything to treat a mouth or tongue ulcer, there are things you can do to aid healing. We offer some treatment and prevention advice later on.

Ask a dentist: Are all canker sores harmless?

Generally, mouth ulcers are harmless – and they go away uneventfully in a few days. However, if you feel that you have an ulcer that has not healed for more than 2 weeks, it is a cause for concern – and you must visit your dentist immediately.

-Dr. Fanar Swaida

Canker sores are not contagious, and shouldn't be confused with oral herpes (cold sores). Cold sores occur around the mouth, tongue or on the lips, and these can be passed from one person to another through contact.

Different types of mouth ulcers

Aside from occasional occurrences, there are three main categories of mouth sore:

  • Recurrent aphthous stomatitis

People with this condition get ulcers frequently; perhaps three or six times a year. This may continue for several years before gradually disappearing. Sores are usually most painful in the days after they first develop.

There is nothing that can be done to cure this condition, but there are ways to manage discomfort during outbreaks, mostly involving symptomatic treatment and preventive care. These ulcers are thought to be somehow linked to the immune system.

  • Giant ulcer

This kind of ulcer is quite rare but extremely painful. It presents as one or more lesions which can be anywhere from 1cm to 5cm in size. Healing can take a month or more and the ulcer often leaves scarring.

  • Miliary ulcer

Also relatively rare, this kind of ulcer appears as clusters of lesions. Several dozen may appear at once. They are very painful but benign, and heal in one or two weeks.

What causes mouth ulcers?

causes of canker sores
Metal brace brackets can irritate the mouth

The exact causes of mouth ulcers are unknown. Simple ulcers are usually blamed on fatigue and stress, or physical damage to the mouth tissue such as abrasions from braces. Wearing metal braces or dentures can irritate the tissue in the mouth and lead to sores. Sharp edges on damaged teeth can have the same effect. Hormonal imbalance in women during menstruation or pregnancy can also cause mouth ulcers.

If you accidentally bite your tongue or slip while brushing your teeth, the resulting damage to your mouth tissue could lead to an ulceration.

There is also some evidence that sodium lauryl sulphate (SLS), an ingredient found in many commercial toothpastes, can cause or aggravate ulcers. If you're worried about adverse effects from your toothpaste, you can read more about toothpaste ingredients here and discover some natural alternatives.

When it comes to more complex cases, the cause of the ulcers is often an underlying health condition. Examples include:

  • A deficiency in folic acid, iron, zinc or vitamin B12
  • Immune system impairment
  • Food allergies
  • Gastrointestinal tract diseases, such as coeliac disease and Crohn's disease
  • A reaction to common medicines
  • Hand, foot and mouth disease
  • Mouth cancer

Also note that people who have just stopped smoking may start getting more canker sores than normal, but this is just temporary. What about e-cigarettes? One of the things that makes vaping bad for teeth is some of the chemicals which may, among other things, irritate and damage soft tissue in the mouth.

Mouth ulcer treatment

when to see a doctor about canker sores
Persistent or severe ulcers may need medical attention

Treatment for aphthous ulcers on the tongue, gums or cheek most often simply involves applying pain relief and antiseptic treatment. This can be in the form of topical rubbing gel, ointment, spray or cream. All you can really do is reduce your discomfort and minimise the chances of overinfection while your body heals the area.

There are some simple steps you can take to help with the healing process:

  • Use a soft toothbrush and brush gently
  • Avoid foods that are very spicy, sour or sweet
  • Stick to soft foods until your mouth ulcers heal
  • Drink through a straw (especially acidic drinks like coffee and fruit juice) to prevent direct contact with the ulcer.
  • Avoid fizzy drinks
  • Avoid chewing gum
  • Consider switching to an SLS-free toothpaste

Once the ulcer has healed you can return to your normal eating and drinking habits, but be sure to get regular dental checkups.

Other types of mouth ulcer may require treatment with medicines prescribed by your doctor, including antibiotics. Occasionally a regular ulcer can become infected and develop into an oral abscess.

You should see a doctor if:

  • You are in severe pain
  • Any pain from the sores persists for more than a few days, or gets worse
  • The ulcers don't clear up after two weeks
  • You have lesions larger than 1 cm in diameter
  • You get more than four lesions at a time
  • They are stopping you from eating
  • You keep getting mouth ulcers (more than four times a year)
  • The ulcers bleed
  • You have a high temperature or you feel tired
  • You have other bodily lesions

Finally, a lesion that looks like a mouth ulcer but causes no pain is quite often not one. You should consult a doctor to check for other oral health problems.

Home remedies for mouth sores

Assuming you have none of the above issues, you may choose to treat your canker sores at home with natural products. Here are a variety of ideas to try if you want to reduce pain, soothe inflammation and keep the area clean:

home remedies for mouth ulcers
Our natural remedies to reduce mouth pain
  • Warm salt water: gargle several times a day for pain relief.
  • Lemon juice: this will sting at first but can offer relief as lemons have anti-inflammatory properties. Apply it with a cotton bud 4 times a day.
  • Ice cubes: the cold will reduce the inflammation and the pain.
  • Liquorice: it can relieve burns and is an excellent healing and anti-inflammatory agent. It presents in the form of a patch you can stick directly over the ulcer in your mouth. Don't worry – the patch does not prevent you from speaking or eating.
  • Black tea: rich in tannins, black tea has analgesic properties. Apply a damp teabag that has been soaked in boiled water and then cooled, and leave it for a few minutes.
  • Cider vinegar: using a cotton bud, apply a little cider vinegar directly onto the canker sore.
  • Sweet bay essential oil: take a cotton bud dipped in a drop of sweet bay essential oil diluted with a little olive oil and rub it directly onto the mouth ulcer.
  • Tea Tree essential oil: apply using a cotton bud 3 times a day, but for no more than 3 days.
  • Clay: with the help of a cotton bud, spread some green clay over the area and leave it for as long as possible.
  • Propolis: this substance that is gathered by bees contains components that are anti-inflammatory, healing, antiseptic, anaesthetic and purifying. You can chew on a bar of propolis and keep it in your mouth for as long as possible. You can also apply a propolis oil solution to the area and massage it or use it as a mouth wash.

The best treatment for mouth ulcers will vary from one person to another, so try a few and see which ones help you. Essential oils are not safe for some people to use and should be properly diluted. Only use these if you understand the risks and know how to use them correctly.

Mouthwash for mouth and tongue ulcers

Ulcers on the tongue may be particularly painful as they rub against your teeth when you talk. These mouthwashes are easy to make at home and help reduce pain and risk of infection:

sodium bicarbonate for mouth ulcers
Household products can be used to make mouthwash for ulcers
  • A bicarbonate of soda mouthwash: to relieve your pain and reduce the risk of infection, mix one teaspoon of salt with one teaspoon of bicarbonate of soda in 120 ml of water. Gargle with this solution 3 or 4 times a day.
  • A green clay mouthwash: dilute one teaspoon of green clay in a glass of warm water, mix and use as a mouthwash at least once a day.
  • A great mullein mouthwash: this medicinal plant will soothe irritations and pain. Pour a cup of boiling water over a tablespoon of great mullein dried flowers and leave to steep for 10 minutes. Filter and use as a mouthwash.

How to treat a baby or child with mouth sores

Ulcers can appear in the mouth at any age, so children and babies are not exempt. In fact, mouth sores are fairly common between the ages of one and three. If you notice your child frowning in pain or crying while trying to eat, check their mouth for ulcers. The pain might make it uncomfortable for them to chew, swallow, or brush their teeth properly.

As with ulcers in adults, they are often benign and disappear by themselves. However they might also be caused by certain foods or medicines or an immune system weakened by childhood illness.

Ulcers in a child's mouth
Children and babies can suffer too

Another common cause of multiple mouth ulcers in children and babies is hand, foot and mouth disease. The ulcers are accompanied by a blistery rash on the hands and feet. The disease should clear up by itself in 7-10 days, but in the meantime the ulcers will cause some discomfort.

If you notice several ulcers at once in your child's mouth, or if they have an ulcer which doesn't seem to be healing, it's best to take them to the doctor.

Do what you can to prevent damage to the tissue inside your child's mouth. We know it can be hard to keep an eye on everything they chew on, but anything rough or sharp is more likely to cause damage and open the way for ulcers. If your child sucks his or her thumb, remember to cut their nails regularly.

While an ulcer is healing, you may administer pain relief as advised by your paediatrician. Also avoid feeding your child very hot, very sweet or very salty food as this can intensify the pain.

Some home remedies are suitable for children but others are not. For example, tea tree oil should not be used before the age of 3. Ask your chemist or doctor for advice, even when it comes to natural treatments.

Read more about this and other oral health problems that can affect children.

How can I prevent mouth and tongue ulcers?

There is no guaranteed way to prevent ulcers in the mouth, but there are some things you can do to reduce the chances of them developing.

Good oral hygiene is, of course, essential. Use a soft toothbrush and take care when you brush to avoid damaging your gums. Floss daily and visit your dentist regularly. Using mouthwash as per the recommendations of your dentist will also help.

You may also find that certain foods and drinks irritate your mouth and cause sores to develop. These are different for each person but commonly include salty foods, spicy foods, hot drinks and acidic foods and drinks. It can be hard to identify a single culprit but if you do, obviously you should limit your consumption of that item.

If you're concerned about developing sores because of braces, consider the different options available. There are many different types of orthodontic braces now on the market, and not all have protruding metal brackets.

The following short video offers helpful advice about mouth sore prevention:


Mouth ulcers are very often benign, but can be quite painful. Although they should disappear by themselves, you may want to treat them to speed up the healing process and reduce any discomfort.

The causes are difficult to identify, so it's better to focus on treating the current problem. You can then take steps to minimise the chances of them redeveloping. There are lots of home remedies which will help relieve pain and stave off infection.

If a canker sore is very painful or completely painless, you should seek medical attention. Also consult a doctor if you keep getting ulcers or they take more than two weeks to clear. They can be a sign of more concerning health issues, so it's best to get checked out if in doubt.


Why are canker sores more common in women?

There is a noticeable difference in occurrence between men and women. Canker sores are more common in women because of the hormonal imbalances they experience during menstruation and pregnancy.

Why do I get canker sores when I am studying for exams?

Stress and anxiety seem to be some of the most common causes of canker sores. That's why many people experience canker sores when studying for exams, or during stressful periods in their lives.

Should I be worried about mouth ulcers?

While they are generally harmless, recurring mouth ulcers can be a sign of an underlying condition. It's also a concern if you have a canker sore which hasn't healed after two weeks. In both of these cases, you should visit a doctor or dentist for advice.

How to Treat a Mouth Ulcer or Canker Sore and Relieve Pain at Home
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NHS (National Health Service) Consulted 24th April 2019.

Oral Health Foundation Consulted 24th April 2019.

NHS inform – Scottish Consulted 24th April 2019.

National Center for Biotechnology Information Consulted 24th April 2019.

University Hospitals Birmingham NHS Foundation Trust Consulted 24th April 2019.