Many people find a mucocele the same way: a smooth, soft bump appears on the inside of the lower lip a few days after they bite it, swells, perhaps bursts, and then fills up again. It is a pocket of saliva from a tiny damaged gland, not a tumour, and it is not contagious. Some settle within a few weeks. Those that keep coming back usually need a small procedure to stop the cycle.
Saliva leaking from a tiny gland
Hundreds of small saliva glands sit just beneath the lining of the lips, cheeks and floor of the mouth. Each drains through a fine duct. If that duct is torn or blocked, saliva seeps into the surrounding tissue instead of into the mouth, and the body walls it off into a soft swelling. Because this pocket has no true lining, it is sometimes called a pseudocyst.
The usual cause is injury. Accidentally biting the lip, a knock during sport or play, or a habit of chewing the inside of the lip can all damage a duct. The lower lip takes most of those bites, which is why it is by far the most common place to find a mucocele. They are common in children and teenagers but can appear at any age.
What one looks and feels like
A typical mucocele is a dome-shaped bump from a few millimetres to around a centimetre across. It is soft, smooth and usually painless, and it may look clear, bluish or the same pink as the rest of the lip. Many go through cycles: the bump swells, breaks and drains a little sticky fluid, then refills over days or weeks.
A large, soft swelling under the tongue on the floor of the mouth is a related lesion called a ranula. It comes from a bigger saliva gland and is assessed and managed differently.
Bursting it at home usually backfires
It is tempting to pierce a mucocele because it looks like a blister. Doing so lets the fluid out for a while, but the damaged gland is still there and still producing saliva, so the swelling tends to return. Piercing it also creates an open wound in a mouth full of bacteria. Leave it alone and let it settle, or have it looked at if it will not go away.
When to have it checked
A small mucocele that appeared after an obvious bite can reasonably be watched for a few weeks. See a dentist if the bump:
- has not gone within 3 weeks, or keeps coming back
- is getting bigger, or interferes with eating or speaking
- feels firm or hard rather than soft
- appeared without any injury you can think of, or is in an unusual spot such as the upper lip
Most lip bumps turn out to be harmless, but a few other lumps can look similar. A dentist will ask how the bump started and how it has changed, then examine it. If anything about it is unusual, the tissue removed during treatment is sent to a laboratory to confirm what it is.
How a persistent mucocele is treated
The standard approach is a minor procedure under local anaesthetic to remove the mucocele together with the small gland or glands that feed it. Taking out the leaking gland is what stops the pocket refilling. The area is usually stitched and heals over a week or two.
Other techniques are also used, including laser removal and micro-marsupialisation, in which stitches are placed through the swelling to create a new drainage path. A 2023 systematic review by Hashemi and colleagues in Medicina Oral, Patología Oral y Cirugía Bucal compared scalpel excision, CO2 laser and micro-marsupialisation and found no significant difference in how often mucoceles came back, although the authors noted that more trials are needed. Which method suits depends on the size and position of the lesion, the patient's age and the clinician's training. Some cases are referred to an oral surgeon or oral medicine specialist.
Recurrence can still happen, most often when a damaged gland is left behind or when the lip keeps being bitten in the same spot.
Lowering the chance of another one
You cannot prevent every mucocele, but you can reduce the most common trigger. Being aware of a lip-biting or lip-sucking habit is the first step. If a sharp or out-of-line tooth keeps catching the lip, a dentist can check whether smoothing or adjusting it would help. Wearing a mouthguard for contact sport also protects the lips from knocks.
Questions about mucoceles
Is a mucocele cancer?
No. It is a benign collection of saliva. Any tissue removed is usually checked in a laboratory, which confirms the diagnosis.
How is it different from a cold sore or a mouth ulcer?
A cold sore is a viral blister on the outer lip that crusts, and an ulcer is an open, painful sore. A mucocele is a smooth, soft, usually painless bump that does not crust. Our guide on cold sores and mouth ulcers explains how to tell those two apart.
Can children have one removed?
Yes. Mucoceles are common in children, and the approach is similar. The dentist will talk through options that suit the child's age and comfort.
If a lip bump has not settled, the team at Lumi Dental in Melrose Park can confirm what it is and explain the options, including referral where that is the best path. Fees vary with the approach, so rather than listing prices here we provide a written treatment plan with fees after assessment at a general dental visit. You can also see our current offers or book through our contact page.
This article is general information and is not a substitute for individual advice. Please see a dentist for diagnosis and treatment tailored to you.
