Blisters in the mouth

Most people get blisters or sores in their mouths at some point. They can be caused by infections, irritation or lack of certain nutrients. Although blisters are often harmless, they can be painful and affect both eating and speech. In some cases, treatment is required.

"Blisters in the mouth is common, but when symptoms recur or do not resolve in two weeks, it is important to have the cause examined by a dentist."
- Sia, dental hygienist at Dentme

What are blisters in the mouth?

Blisters in the mouth are small fluid-filled bumps that often appear on the inside of the cheeks, tongue, gums or palate. They can be painful and make it difficult to eat, talk or brush your teeth. In some cases, they develop into open sores.

Common causes of blisters in the mouth

Herpes (oral herpes)

Caused by the herpes simplex virus, blisters often appear on the lips or in and around the mouth. Can be triggered by stress, sunlight or infection.

Aphthae (aphthous stomatitis)

Small, yellowish-white ulcers in the mucosa. Not contagious. Often unknown cause but common in young adults.

Dry mouth

Too little saliva makes the mucous membrane sensitive and more susceptible to blisters and infections.

Fungus in the mouth (oral candidiasis)

Often causes a whitish coating, redness and sometimes burning or blistering.

Inflammatory conditions

For example, oral lichen planus - a chronic inflammation of the oral mucosa.

Mechanical irritation

Can be caused by dentures, sharp teeth, toothbrush damage or food.

Nutritional deficiency

Deficiencies of B12, folic acid or iron can negatively affect the oral mucosa.

Symptoms of blisters in the mouth

- Pain and burning

- Swelling and redness

- Fluid-filled blisters

- White or yellowish sores

- Difficulty eating or speaking

When should you seek medical help?

Contact your dentist or doctor if:

- The blisters do not heal within two weeks

- You get a fever, severe pain or swelling

- You have recurrent problems

- You suspect fungus or herpes

Treatment of blisters in the mouth

The treatment depends on the cause:

- Herpes: Antiviral drugs (e.g. acyclovir)

- evening: Over-the-counter ointments, local anesthetics or cortisone solutions

- Sponge: Fungicides (nystatin or fluconazole)

- Lichen planus: Cortisone and dental check-ups

- Irritation: Adjustment of prostheses or dentures

Preventive advice

- Maintain good oral hygiene

- Brush your teeth and tongue twice a day

- Avoid smoking and snus

- Rinse your mouth after using inhalers

- Eat a balanced diet rich in vitamins and minerals

- Avoid hard, sour or spicy foods if you are sensitive

Frequently asked questions about blisters in the mouth

How long does it take for blisters in the mouth to heal?
Most blisters disappear within 7-14 days. In case of recurrence or persistence, you should seek medical attention.

Are blisters in the mouth contagious?
Munherpes is contagious, but aphthae and most other blisters are not.

What can I do myself to relieve mouth blisters?
Use salt water rinses, eat soft foods and avoid irritants. Over-the-counter anesthetic gels can provide temporary relief.

Can vitamin deficiency cause mouth blisters?
Yes, especially deficiencies of B12, iron and folic acid can negatively affect the mucosa.

Can stress cause mouth blisters?
Yes, stress is a known trigger for both herpes and aphthae.

Sources used by Dentme:

1177 Vårdguiden - Aphthae (sores in the mouth)
https://www.1177.se/behandling--hjalpmedel/behandlingar/munnen/afte-sar-i-munnen/
1177 Vårdguiden - Blisters and sores in the mouth
https://www.1177.se/sjukdomar--besvar/mun-och-tander/mun-lappar-och-tunga/blasor-och-sar-i-munnen/

1177 Vårdguiden - Munsår (herpes around the mouth)
https://www.1177.se/sjukdomar--besvar/mun-och-tander/mun-lappar-och-tunga/munsar--herpes-runt-munnen/

1177 Vårdguiden - Mouth pain in children
https://www.1177.se/sjukdomar--besvar/mun-och-tander/mun-lappar-och-tunga/ont-i-munnen-hos-barn/

NHS (UK) - Mouth ulcers
https://www.nhs.uk/conditions/mouth-ulcers/