A man holding out his lip, displaying a mouth ulcer

Mouth ulcers – causes and treatments

Chances are you’ve experienced a mouth ulcer before. They can be extremely painful and uncomfortable, but it’s important to remember that they are very common and are rarely a sign of anything serious.[1]

So what exactly is a mouth ulcer and why do they hurt so much? In this article, we take a closer look at how you can avoid mouth ulcers to maintain good oral hygiene, and what you can do to help treat these types of sores.

What is a mouth ulcer?

A mouth ulcer is a painful sore that appears inside the mouth. They are often round or oval-shaped, and they can form on the tongue, lips, gums, inner cheeks or roof of the mouth. Mouth ulcers can be white, yellow, red or grey in colour, and they are usually swollen. It’s possible to have more than one ulcer at a time, and they can sometimes spread or grow.[1]

Mouth ulcers are not contagious and they should not be confused with cold sores. Cold sores are small blisters that can develop on the lips or around the mouth and are often accompanied by an itching or burning sensation.[2]

Why do ulcers hurt so much?

Mouth ulcers can often be so painful that they make it difficult to eat, drink, brush your teeth and even talk – but why do they hurt so much? Put simply, your saliva contains special enzymes and acids that help break down the food you eat – but they can get into mouth ulcers too. Since a mouth ulcer is essentially an injury to the inside of your mouth, this can cause you a considerable amount of pain and discomfort.[1]

Why do you get mouth ulcers?

Most mouth ulcers are caused by damage to the lining of the mouth, but it can be difficult to pinpoint the exact cause of these sores. In fact, there are many reasons why you might develop a mouth ulcer. Below, we take a look at some of the most common causes.

Biting the inside of your cheek or lip

It’s likely you’ve accidentally bitten the inside of your cheek or lip before. This can often happen while you’re eating something or chewing gum, and it can be extremely painful and uncomfortable. It’s not unusual for an ulcer to appear as a result of this.[1]

Poorly fitted dentures or braces

If you have poorly fitted dentures or braces, it can be easy to catch the inside of your mouth and develop an ulcer. You may even get an ulcer as a result of a rough or defective filling, or if you’ve got a particularly sharp tooth. If you think any of these reasons is to blame for your mouth ulcers, you should speak to your dentist.[1]

The food you eat

It could be that there is a certain food which causes you to develop mouth ulcers. Some people find that foods such as chocolate, cheese, strawberries, almonds, peanuts, tomatoes and spicy meals can irritate the mouth and trigger these sores to develop. You may also notice that you break out with an ulcer after eating food that’s particularly hard or if you have a hot drink, such as coffee. It’s also possible that an intolerance to a specific food or an allergy could be why you struggle with mouth ulcers, especially if you develop these sores on a regular basis.[1]

Your toothpaste

Believe it or not, the toothpaste you use could be to blame for your mouth ulcers. Some toothpastes contain sodium lauryl sulphate which can be extremely irritating. Mouth ulcers can also be worsened if you brush too vigorously with your toothbrush. Instead, you should use a soft bristled brush and a gentle brushing technique so as not to damage the gums, reducing your chances of developing an ulcer.[1]

Your health

Your health can play a part in how often you develop mouth ulcers. For instance, mouth ulcers can sometimes be triggered by certain medical conditions, including viral infections such as chickenpox and hand, foot and mouth disease, as well as iron or vitamin B12 deficiency. Those with digestive conditions, such as coeliac disease and Crohn’s disease, or a weakened immune system, may also be susceptible to mouth ulcers.

Some medications or treatments can cause mouth ulcers too. For example, they can often be a side effect of radiotherapy or chemotherapy, and they can even flare up as a result of non-steroidal anti-inflammatory drugs, such as ibuprofen, and the use of medications like beta-blockers and nicorandil.

You may also find that you develop mouth ulcers when you’re feeling particularly run down or tired, or if you’re stressed or anxious.[1]

Stopping smoking

If you have recently given up smoking, you may find that you’re more prone to mouth ulcers. It’s not fully understood why this happens, but it’s suggested that there is a link between the lack of antibacterial properties present in the mouth once a person gives up this habit.[1]

Hormonal changes

When a woman’s progesterone hormone increases during the menstrual cycle, she may find that she suffers with mouth ulcers, among other oral changes like swollen or bleeding gums. Hormonal changes during pregnancy can trigger mouth ulcers too.[1]

How to treat mouth ulcers

Usually, mouth ulcers don’t need to be treated, as they often heal and clear up by themselves. However, there are a few things you can try at home to help ease any pain or discomfort you may be experiencing.

For example, you could ask your pharmacist to recommend a protective topical paste or gel that you can apply to the ulcer to provide quick, effective relief. A pharmacist can also recommend treatments such as an antimicrobial mouthwash, corticosteroid lozenges or a saline mouthwash to rinse with, all of which can help speed up the healing process, reduce pain and prevent infection.

You should also try to avoid eating food that is particularly hot, spicy, hard, salty or acidic, and you may want to stick to cool drinks while your ulcer heals. You could find that using a straw helps too.

It’s best to avoid chewing gum while your ulcer heals, and you might want to use a softer toothbrush and swap your toothpaste for a version which does not contain sodium lauryl sulphate.[1]

How long do mouth ulcers take to heal?

In most cases, you can expect a mouth ulcer to heal within one to two weeks. If you have an ulcer that is taking longer to heal than this, you should speak to your doctor or dentist for further advice.[1]

How to tell if a mouth ulcer is healing

You will be able to tell if your mouth ulcer is healing if it starts to reduce in size as the swelling of the area decreases, and you should find that it begins to feel less painful and uncomfortable. You may also notice that the colour of the area starts to return to normal, by which time it’s likely the ulcer has completely cleared up.[1]

When should you seek medical advice about an ulcer?

If you’ve had a mouth ulcer for more than three weeks, you notice that it keeps coming back, it has grown bigger than usual or if it’s near the back of your throat, you should seek medical advice from either your GP or your dentist. You should also get further advice if you have a mouth ulcer that has started to bleed or has become more painful and red, as this can be a sign of an infection.[1]


[1] https://www.nhs.uk/conditions/mouth-ulcers/

[2] https://www.nhs.uk/conditions/cold-sores/

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