6 Nov
November 6, 2023
Marzyeh Parvizi



A mouth blister is quite common, particularly cold sores and canker sores. Blisters can affect people at any age, although certain types of sore are more likely to affect certain age groups.

Typically, mouth blisters are not harmful and clear up within a week or two. However, some types of sores can be indicative or a more serious health condition, such as oral cancer.

Blister sores can surface on the tongue, lips, on the inside of the cheeks, as well as on the roof and floor of the mouth. Sores can vary in color, but tend to be red, white, yellow or purple depending on the type of sore.

While blisters do not usually require a medical diagnosis, if you experience severe blistering, sores which do not clear up and recurring sores you should consult with your doctor.

The precise symptoms of a mouth blister can vary depending on the type of sore you have and its cause. However, there are several common symptoms indicative of blisters developing in the mouth. These include:

  • redness
  • blistering
  • pain when eating or drinking
  • discomfort when swallowing
  • tingling or burning sensation around the sore
  • bleeding

There are further symptoms, ones which you should consult your doctor about if you experience them. These include:

  • recurring sores
  • skin rash
  • fever or diarrhea
  • sores over half an inch in diameter
  • excessive pain
  • joint pain

There are several factors which can contribute toward mouth blisters. Again, different types of blisters can result from specific risk factors. Some of these may be down to lifestyles and underlying health issues, while others could be due to a viral or bacterial infection.

Lifestyle factors include:

  • stress
  • smoking
  • alcohol consumption
  • biting the inside of the mouth
  • hot food or drinks burning the inside of the mouth
  • hormones
  • irritation from orthodontics like braces
  • using a hard-bristled toothbrush and brushing aggressively

Health conditions and infections which may be contributing factors for mouth blisters include:

  • Herpes Simplex virus
  • Crohn’s disease
  • HPV
  • HIV/Aids
  • Anemia
  • Celiac disease
  • Mononucleosis
  • Folate deficiency
  • Lupus
  • Blister in Mouth: What Are the More Common Forms of Sores?

This is a relatively common form of mouth blister which will affect around 20 to 40% of us. They are caused by the Herpes Simplex virus and are also known as fever blisters as a mild fever can be one of the symptoms.

Stress and a weakened immune system increase your risk from cold sores. The blisters look like fluid filled sores around the mouth and lips.

A tingling sensation can announce the arrival of cold sores, which are contagious for up to 15 days and can be passed on through kissing and sharing utensils when you eat.

This is another common type of mouth blister, which around 20% of the population can expect to develop at some point. Unlike cold sores, canker sores are not contagious and usually vanish within two weeks.

The sores are like small ulcers in appearance. Typically. they are red and can have areas of yellow, white or grey within them. Biting or burning the inside of the mouth are common causes of canker sores. However, health conditions like Crohn’s disease can also be a contributing factor.

This is quite a common condition, one more normally seen in children. The blisters tend to appear on the gums or inner cheeks and may be caused by an infection. Poor oral hygiene can also be a contributing factor. The sores can be tender and cause pain while eating, which may sometimes be severe. This can see younger children refusing to eat.

Oral thrush is caused by a yeast infection resulting from an excess amount of the fungus Candida albicans in the oral cavity. The creamy white lesions which form on the tongue are the most prominent symptom of this infection.

Thrush often results from a weakened immune system. It can also be caused by medications and treatments for other health conditions. A doctor may scrape a sample of the lesions for analysis in order to confirm oral thrush.

Oral cancer results from abnormal cell growth and can affect all areas of the mouth, including the tongue and lips. It can present as red or white sores or patches. However, with oral cancer, these sores or patches do not heal.

A doctor can perform a biopsy to check for cancerous cells. An early diagnosis increases the chance of a better outcome. Studies show one in nine people with Leukoplakia, sores common from tobacco use, may go on to develop oral cancer.

Mouth sores often vanish of their own accord in a week or two. However, there are a few things you can do at home to help them heal and to ease any discomfort. This includes:

  • gargle with warm saltwater a few times each day
  • avoid hot and spicy foods
  • eat cold food items such as ice pops
  • avoid alcohol and tobacco
  • resist the temptation to squeeze sores
  • take over-the-counter pain relief such as acetaminophen (Tylenol)

If you have to see your doctor about mouth blisters, they may prescribe you with pain relief, a steroid gel or an anti-inflammatory medication.

Of course, prevention is always the best way forward where possible. Ways to prevent a mouth blister include:

  • maintain good oral hygiene routine
  • eat a balanced diet
  • exercise to boost the immune system
  • avoid tobacco
  • reduce alcohol consumption
  • find ways to reduce stress, like meditation
  • drink plenty of water through the day
  • apply lip balm when in the sun
  • use a soft-bristled toothbrush

Mouth blisters usually disappear within two weeks without causing long-term harm. However, you should seek medical advice for severe sores and sores that do not heal or are re-occurring.


Mouth blisters are not harmful and clear up within a week or two. However, some types of sores can be indicative or a more serious health condition

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