Ulcerative colitis (UC) may cause sores to develop in a person’s mouth. These can include canker sores, pyostomatitis vegetans, and other mouth changes. Some UC medications may also cause mouth sores.

Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD). UC causes inflammation in the colon, which typically causes symptoms such as diarrhea, abdominal pain, and bloody stools.

If a person develops mouth sores, it is important to contact a doctor for a diagnosis. The doctor can determine whether UC is causing the mouth sores and advise on a suitable treatment plan where necessary.

Read on to learn more about the possible link between UC and mouth sores, including which medications can cause them. This article also looks at treatments for people with UC who are experiencing mouth sores.

View the slideshow below for photos of mouth sores associated with UC.

Canker sores, or aphthous ulcers, are small mouth ulcers that may appear between the lower lip and the gum. They can also appear along the side or base of the tongue.

Canker sores tend to appear during severe UC flare-ups and often go away once the flare-up has finished. A 2018 study found that canker sores could help determine the occurrence of a UC flare-up, as well as help indicate whether a person is experiencing relapse or remission from the condition.

These sores can be painful and may make it difficult to eat and speak. The Crohn’s & Colitis Foundation suggests that the following may help:

  • medicinal mouthwash
  • taking multivitamins or mineral supplements, at a doctor’s advice
  • consuming a nutritious, balanced diet

Learn more about treating canker sores.

Pyostomatitis vegetans (PV) is a rare and chronic condition that causes lots of white or yellow pustules to develop inside a person’s mouth. It can develop if a person has UC or other IBD.

A person may also develop pyodermatitis-pyostomatitis vegetans (PPV). This means that symptoms affect both the inside of the mouth and the skin.

Treating UC may help symptoms of PV resolve. In some cases, a doctor may recommend medication to specifically target PV. A 2020 report noted that the monoclonal antibody medication ustekinumab helped treat PV in one case of Crohn’s disease, another type of IBD.

People with UC may also notice they have a dry mouth, or xerostomia. According to a small 2020 study, this condition can affect a person’s quality of life.

A 2022 research review indicated that dry mouth is linked to disease activity. This means that it is more likely to happen during a flare-up.

Managing UC to help reduce the number or severity of flares can help reduce the likelihood of having a dry mouth.

A person can also take steps to reduce symptoms of a dry mouth, including:

  • drinking cold water
  • sucking on ice
  • chewing sugar-free gum

Learn more about home remedies for dry mouth.

As well as mouth sores and dryness, a person with UC may experience other conditions or changes affecting the mouth.

Taste changes

People with UC may experience a change of taste.

One 2020 study showed that people with IBD had reduced taste sensitivity to specific flavors. They experienced a reduction in taste when eating foods with the following flavors:

  • sweet
  • salty
  • bitter
  • umami
  • fatty

However, people with IBD actually had an increased perception of sour flavors when compared with people without the condition.

Bad breath

Bad breath, or halitosis, may also affect a person with UC.

This may be related to dry mouth, as saliva tends to wash away dead cells and bacteria that are present in a person’s mouth.

Conditions such as periodontitis and gingivitis, which may also develop in people with UC, can also lead to bad breath.

Learn some home remedies for bad breath.

Other changes

Some other oral issues that UC may cause include:

A person with UC may experience mouth sores as a result of side effects from certain medications. If a person feels their medication is causing their mouth sores, it is important to contact a doctor for advice before making any changes to their treatment plan.


UC medications that may cause mouth sores include aminosalicylates, such as sulfasalazine. They can cause mouth sores and changes to taste.

If a person does develop mouth sores when taking aminosalicylates, it is important that they tell their doctor immediately.


Mouth sores are a possible side effect when taking the immunomodulator mercaptopurine (6-MP). A person should contact a doctor for advice if they take this medication and develop mouth sores.


Medical professionals also prescribe corticosteroids to treat UC.

While there is little evidence that corticosteroids can cause ulcers in the mouth, there is some evidence linking these drugs with the occurrence of candidiasis in the mouth.

Candidiasis is a fungal infection that causes white patches to develop inside the mouth and throat. This can cause soreness in the mouth and may affect a person’s taste.

Candidiasis can also develop as a result of the following medication therapies:

  • infliximab
  • thiopurines
  • cyclosporin A

Learn more about medications and treatments for UC.

Following a suitable treatment plan for UC can help a person manage the condition, which in turn may help reduce mouth sores.

A person can also take other steps to help prevent them from developing or to encourage healing. These include:

  • avoiding very hot food and drinks
  • avoiding abrasive foods and food that may stick in the mouth
  • avoiding spicy and acidic foods
  • practicing regular good dental hygiene
  • using a soft toothbrush and avoiding scratching the inside of the mouth
  • avoiding smoking or using tobacco
  • drinking plenty of water
  • managing stress or anxiety

Depending on the cause, a mouth sore may heal on its own without medical treatments. However, a person may wish to contact a doctor if they have had a mouth sore for 3 weeks.

They may also wish to contact a doctor if their mouth sores worsen with or without treatment, or if mouth sores come and go frequently.

The doctor can help diagnose the type of mouth sore and advise on a suitable treatment plan where necessary. This may include making modifications to an existing UC treatment plan.

Ulcerative colitis (UC) is a type of inflammatory bowel disease (IBD) that causes inflammation and ulcers to occur in a person’s colon.

Some people with UC will develop mouth sores. Canker sores or pyostomatitis vegetans may develop. A person may also experience a dry mouth, taste changes, and bad breath.

Depending on the type of sore, it may heal without treatment. A person may wish to try some home remedies to soothe symptoms while the sore heals.

If mouth sores last for at least 3 weeks, or if they keep returning, it is best to contact a doctor for advice. They may recommend changes to an existing treatment plan for UC, and in some cases, they may prescribe medication to treat sores directly.