A mucous cyst develops when the mouth’s salivary glands become plugged with mucus. While they’re usually temporary and painless, they can become permanent if not treated.

What are mucous cysts?

A mucous cyst, also known as a mucocele, is a fluid-filled swelling that occurs on the lip or the mouth.

The cyst develops when the mouth’s salivary glands become plugged with mucus. Most cysts are on the lower lip, but they can occur anywhere inside your mouth. They’re usually temporary and painless. However, cysts can become permanent if they’re not treated.

Mucous cysts are most commonly caused by trauma to the oral cavity, such as:

  • lip biting (most common cause)
  • cheek biting
  • piercings
  • accidental rupture of a salivary gland
  • adjacent teeth causing chronic damage

Poor dental hygiene and a habit of lip or cheek biting due to stress can also put you at higher risk for developing mucous cysts. Some people develop these cysts as a bad reaction to tartar-control toothpaste.

Mucous cysts are most common in people ages 10 to 25. However, these cysts can occur in people of all ages. They also happen equally in both females and males.

The symptoms of a mucous cyst vary by how deep the cyst lies within the skin and how often the cysts occur. Most cysts are not painful, but they can be uncomfortable. Frequent cysts can become painful over time.

Symptoms of cysts near the surface of the skin include:

  • raised swelling
  • bluish color
  • softness
  • lesions less than 1 centimeter in diameter

Symptoms of cysts deeper within the skin include:

  • rounded shape
  • whitish color
  • tenderness

You should see a doctor for any cyst that appears in or around your mouth. You’ll want to receive a proper diagnosis and your doctor can rule out more serious conditions. You should also see a doctor if the cyst becomes large and uncomfortable. Though most mucous cysts are less than 1 centimeter in diameter, rare cases can result in cysts as large as 3.5 centimeters.

Smaller, painless cysts are often not detected until you go to the dentist. This is especially true of mucous cysts that develop inside your mouth. Your dentist may refer you to a medical doctor for a biopsy and other diagnostic tests.

In most cases, your doctor will let a mucous cyst heal on its own. If the cyst is still there after two months, see your doctor again.

Doctors rely on clinical symptoms for diagnosis. Your doctor may also ask if you have a history of trauma associated with lip biting. Your answer will help your doctor make an accurate diagnosis.

In certain cases, a biopsy of the cyst may be needed to make a positive diagnosis. During this procedure, your doctor will remove a small tissue sample. The tissue will be examined with a microscope. By looking at the cells, doctors can determine if the cyst is cancerous or not.

Doctors may require a biopsy in cases where:

  • the mucous cyst is larger than 2 centimeters
  • the cyst’s appearance suggests adenoma (cancer) or lipoma
  • there is no history of trauma

Treatment is based upon the severity of the mucous cyst. Sometimes cysts may not require treatment and will heal on their own over time. Superficial cysts often resolve on their own. To prevent infection or tissue damage, do not try to open or remove cysts at home. Frequent or recurring cysts may require further medical treatment.

Treatments used in mucous cysts that are not very severe include:

  • Laser therapy. This treatment uses a small, directed beam of light to remove the cyst.
  • Cryotherapy. This treatment removes the cyst by freezing its tissues.
  • Intralesional corticosteroid injection. This treatment injects a steroid into the cyst to reduce inflammation and speed up healing.

To prevent recurrence — or to treat especially severe cysts — your doctor may recommend surgical removal of the cyst or even the complete salivary gland.

Mucous cysts can take anywhere from a week to two years after treatment to heal, depending on the type and severity of the cyst.

Even after healing, the only way to ensure a cyst will not come back is to have it surgically removed. Avoid habits like lip or cheek biting to help prevent future cysts.

Oftentimes, recovering from a mucous cyst simply takes time. You should occasionally check the cyst to make sure it does not become infected, and that it’s not getting any larger. Warm saltwater rinses may help speed up the healing process.

If you’re a regular lip or cheek biter, you might also consider breaking these types of habits. Keep a journal and keep track of how often you bite — it’s most likely related to stress, anxiety, or boredom. Once you’ve identified the triggers, you can try to find ways to stop biting your lips and cheeks. Chewing on sugarless gum is just one method you can use to satisfy the urge to bite without harming yourself.

While home remedies might be helpful in healing some mucous cysts, it’s important that you avoid self-diagnosis. Your doctor can make sure the bumps aren’t related to something more serious, such as oral cancer.

Once identified and properly diagnosed, mucous cysts have a good recovery rate. These are benign (noncancerous) cysts, so they do not pose any long-term health concerns. The greatest complications with mucous cysts are pain and discomfort. If you suspect a mucous cyst in or around your mouth, get it checked out promptly.