Oral Mucous Cyst

Medically Reviewed by Robert Brennan on March 22, 2023
3 min read

An oral mucous cyst, also called a mucocele, is a harmless swollen spot. It's a good idea to get it checked out, though, especially if it's bothersome.

There are two types. Mucoceles show up on the inside of your lower lips, your gums, the roof of your mouth, or under your tongue. Those on the floor of the mouth are called ranulas. These are rare, but because they’re larger, they can cause more problems with speech, chewing, and swallowing.

Mucoceles may have these traits:

  • Moveable and painless
  • Soft, round, dome-shaped
  • Pearly or semi-clear surface or bluish in color
  • 2-10 millimeters in diameter


Where does an oral cyst come from? It centers on a small salivary gland, which makes saliva in your mouth.

Here's what happens:

Your saliva moves from a salivary gland through tiny tubes (ducts) into your mouth. One of these ducts can become damaged or blocked. This most often happens if you repeatedly bite or suck on your lower lip or cheek.

Getting hit in the face could also disrupt the duct. Remember that "head-on collision" in your pickup game of basketball last month? Maybe that was the original culprit.

What happens once the duct damage is done? Mucus seeps out, pools, becomes walled off, and causes a cyst-like swelling. A similar buildup happens when the duct has become blocked.

A few other common causes include:

  • A tear in a salivary gland: A bump or injury could cause swelling or inflammation to the salivary gland and lead to mucus buildup.
  • Piercings: Cysts can form because of an infection, especially with lip piercing. You should have any piercings done by a professional to assure clean, sterile instruments and avoid infections.
  • Damage caused by your teeth: Not taking care of your teeth can lead to a buildup of bacteria. That bacteria can block salivary glands and lead to cysts.

Your doctor might be able to tell that you have a mucocele just by looking at it. If not, they may recommend one of these:

  • Biopsy: Your doctor will take a tiny sample of the cyst and send it to a lab for a closer look.
  • Ultrasound: This uses sound waves to show images of the inside of the cyst on a computer screen.
  • Computerized tomography (CT) scan: This is a series of X-rays taken at different angles; put together, they give your doctor a more detailed image of the cyst.


Mucoceles often go away without treatment. But sometimes they enlarge. Don't try to open them or treat them yourself. See your doctor, your child's pediatrician, or your dentist for expert advice.

These are the two types of treatment a doctor or dentist most commonly uses:

Removing the gland. The dentist or doctor may use a scalpel or laser to remove the salivary gland. Local anesthesia numbs the pain.

Helping a new duct to form. Called marsupialization, this technique helps a new duct form and helps saliva leave the salivary gland.

The dentist or doctor:

  • Disinfects the area
  • Puts a stitch through the mucocele and ties a knot
  • Gently presses out saliva
  • Removes the stitch after about a week

Other types of treatment that may bring down swelling or prevent the need for surgery include steroid shots and medications applied to the surface of the mucocele.

Mucocele cysts are more unpleasant than harmful, but you still should see a specialist to take care of them. They can return after removal, and there may be pain in areas where they’re removed.

Be aware when cysts may pop up, and try to avoid the temptation to suck on your cheek or bite on your lip when they do appear. If you notice a cyst or a mass in your mouth or have trouble swallowing or talking, call your doctor to set up the right course of treatment.