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Updated on September 30, 2022

Bump Inside Lip (Mucous Cyst)

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What is a Mucous Cyst?

An oral mucous cyst or oral mucocele is a harmless, fluid-filled swelling on the inner surface of the mouth. It happens because of trauma or salivary gland blockage. Oral mucoceles are the most common noncancerous salivary gland lesion.

Mucoceles can develop anywhere on the buccal mucosa, including the lips, gums, the roof of the mouth, or under the tongue. The lower lip is the most typical site, usually due to lip biting.1

When mucoceles develop on the floor of the mouth, they are called ranulas. These growths are more common in older adults. If they are large enough, they can cause problems with speech, swallowing, and even breathing.

What Does a Mucous Cyst Look Like? 

A mucocele may appear as single or multiple nodules. They usually have the following characteristics:2

  • Painless
  • Movable
  • Soft
  • Round or dome-shaped
  • Translucent with a red, pink, or blue tinge
  • 2 to 10 mm in size

Ranulas on the floor of the mouth usually look like a cup-shaped, bluish-colored swelling. They tend to be larger than other mucoceles as they can reach several centimeters in diameter.

Symptoms of an Oral Mucous Cyst 

Symptoms may depend on the extent of the mucocele, but most are uncomfortable rather than painful. However, if they recur frequently, they may become more tender.3

If the mucocele is near the skin’s surface, it may show up as a swollen, fluid-filled sac with a bluish tinge. If the mucocele is in a deeper layer, it may appear more round and white. It may also be more painful than a more superficial mucocele. 

What Causes Oral Mucous Cysts?

Mucoceles are most common between the ages of 10 to 25 but can occur at any age. They also occur equally as often in females and males.4

Trauma or salivary gland blockages cause mucoceles. Lip biting is the most common traumatic cause of mucous cysts. Other causes include:

  • Cheek biting
  • Cheek or lip piercings
  • Rupture of a salivary gland
  • Friction from teeth
  • Poor dental hygiene

Some people can develop oral mucous cysts as a bad reaction to tartar-control toothpastes or frequent mouth washing with hydrogen peroxide.

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When to See a Doctor

If you notice any swelling in or around your mouth, you should see a doctor. They can diagnose the condition correctly and rule out anything serious.

In most cases, mucous cysts are small, painless, and harmless. However, cysts can grow to several centimeters in size. They may then interfere with important functions such as breathing. Therefore, it's best to seek treatment before this happens.

If you have a small, painless cyst, you may not know until you visit the dentist. Mucous cysts can develop inside the cheeks at the back of the mouth, and you may not even notice them. If your dentist finds a cyst, they may refer you to a doctor for testing and diagnosis.


Doctors diagnose mucous cysts based on clinical symptoms. They may ask if you bite your lip or have experienced other trauma to your mouth. They will then physically examine the cyst.

Depending on their findings, the doctor might take a biopsy of the swollen area. This involves removing a small tissue sample with a sterile needle. This sample is then sent away for laboratory analysis. The lab examines the tissue under a microscope to see what kind of cells are present and come up with a diagnosis.

A doctor may recommend a tissue sample if the cyst's appearance is suspicious or there are no obvious causes.

Professional Treatment 

Your doctor decides on the best mode of treatment based on the cyst's severity and your symptoms. Most superficial cysts don't require any treatment, and they heal by themselves within a couple of months. Nevertheless, if the cyst remains after two months, you should return for expert advice.

It's important not to attempt to drain or remove cysts at home. This practice increases the risk of infection and tissue damage.

If cysts recur frequently, your doctor may recommend medical treatments, including:5

  • Laser therapy — this therapy involves using a targeted beam of high-power light to remove the cyst under local anesthesia.
  • Cryotherapy — the doctor freezes the cyst using liquid nitrogen, which is extremely cold and destroys the mucocele. 
  • Intralesional corticosteroid injection — these steroid injections reduce inflammation and accelerate healing.

If you have reoccurring, severe, or painful cysts, your doctor may recommend a more complex surgical approach, such as removal of the salivary gland.

Following treatment, it can take several months for a mucous cyst to heal, depending on its type, location, and severity. 


Once a cyst has healed, the best way to prevent reoccurrence is to avoid mouth trauma. If you have a habit of lip biting or cheek chewing, you need to find out why. Some people bite their lips because of anxiety or nervousness. If this applies to you, ask your doctor for stress-controlling techniques or a referral for behavioral therapy.6

Your doctor may also recommend reducing the use of certain toothpastes or mouthwashes that can irritate the mouth and cause mucosal cysts.

In some cases, oral mucous cysts happen by chance and cannot be prevented. However, if they are an ongoing problem, the only way to prevent them may be to remove the salivary gland surgically. 

Complications from Treatment

Treatment of oral mucous cysts has a good recovery rate with few complications or long-term issues. 

Some complications during surgical removal of oral mucosal cysts include: 

  • Hemorrhage
  • Nerve damage

In some cases, you could experience the following issues after treatment:

  • Infection
  • Recurrence 
  • Scar tissue 
  • Reopening of the surgical wound

Home Remedies for Oral Mucous Cysts

There are no effective home remedies for lesions like oral mucous cysts, although some people find that warm salt water rinses help accelerate the healing process and prevent infection. 

Usually, oral mucous cysts heal by themselves, and recovery is only a matter of time. Nevertheless, it’s best to check the cyst regularly to ensure it hasn't grown larger or become infected. It is also important to see a doctor to make sure it is not related to anything more serious, like oral cancer.  


Oral mucous cysts are benign, fluid-filled sacs that can develop in the mouth. They're usually painless and cause no other health problems.

Most oral mucous cysts don't require treatment and resolve on their own with time. If a cyst recurs or is tender, doctors can treat it with steroid injections, laser therapy, cryotherapy, or surgery.

If you develop any swelling or growths in your mouth, see a doctor. They can accurately diagnose the condition and rule out any serious causes.

6 Sources Cited
Last updated on September 30, 2022
All NewMouth content is medically reviewed and fact-checked by a licensed dentist or orthodontist to ensure the information is factual, current, and relevant.

We have strict sourcing guidelines and only cite from current scientific research, such as scholarly articles, dentistry textbooks, government agencies, and medical journals. This also includes information provided by the American Dental Association (ADA), the American Association of Orthodontics (AAO), and the American Academy of Pediatrics (AAP).
  1. Chaitanya, P., et al. “Mucocele on Lower Lip: A Case Series.” Indian dermatology online journal
  2. Nallasivam, K., et al. “Oral mucocele: Review of literature and a case report.” Journal of pharmacy & bioallied sciences
  3. Huzaifa, M., et al. “Mucocele and Ranula.” StatPearls publishing
  4. Kim, J.H., et al. “Concurrent occurrence of mucocele and pyogenic granuloma.” Annals of dermatology
  5. Seo, J., et al. “Oral Mucocele of Unusual Size on the Buccal Mucosa: Clinical Presentation and Surgical Approach.” The open dentistry journal
  6. Kubo, KK., et al. “Mastication as a Stress-Coping Behavior.” BioMed research international
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