Mucocele (Mucous Cyst) and Ranula

Medically reviewed by Dr. CJ Henley, DMD, general dentist, Jacksonville, FL · Last reviewed October 2026

A mucocele is a soft, painless, fluid-filled bump, most often on the inside of the lower lip. Many people find one with their tongue a few days after biting their lip. It may look clear or a little blue, it can pop and then fill right back up, and it's almost always harmless.

What is a mucocele?

Your lips, cheeks, palate and the underside of your tongue are lined with hundreds of tiny salivary glands, each about the size of a grain of rice. Each one empties through a short duct onto the surface. When one of those ducts gets cut or crushed, usually from biting your lip, saliva leaks out of the duct and pools in the tissue around it. The body walls that pool off, and you end up with a soft, round bump. That's a mucocele.

People often call it a mucous cyst or a mucocele cyst, but it isn't technically a true cyst. A true cyst has its own lining of cells. A mucocele is just a pocket of spilled saliva surrounded by scar-like tissue. The medical name for the common type is mucous extravasation phenomenon. A less common type, the mucous retention cyst, happens when a duct gets blocked and swells. It tends to show up in older adults and in places other than the lower lip.

When the same thing happens to the larger sublingual gland under the tongue, the result is bigger and has its own name: a ranula.

What a mucocele looks like

Most mucoceles are easy to recognize once you know what you're looking for:

• A smooth, round dome that feels soft and a little squishy, like a water balloon.
• Clear, bluish or translucent when it sits close to the surface. Deeper ones look the same pink color as the rest of your lip.
• Anywhere from 1 or 2 mm to more than 1 cm across. Most are about the size of a pea or smaller.
• Painless, though it can be annoying, get in the way when you chew, and tempt you to bite it again.
• Comes and goes. It may break open and leak a clear, sticky fluid, flatten out, and then fill back up over a few days.

How a mucocele forms

The sequence is simple. You bite your lip, often without noticing. A tiny duct tears. The gland behind it keeps making saliva, but now the saliva has nowhere to go except into the surrounding tissue. Over a few days that leak collects into a bubble just under the surface.

That last label explains a lot. The gland feeding the mucocele doesn't know anything is wrong. It keeps producing saliva, which is why draining a mucocele, or having it pop on its own, rarely fixes it for good.

Where mucoceles show up

About 80% of mucoceles form on the inside of the lower lip, usually off to one side where the lower teeth catch it. That's why "mucocele lip" and "mucocele on lip" are how most people first search for this. Other spots include:

• Under the tongue (floor of the mouth). A mucocele under the tongue that comes from the sublingual gland is called a ranula.
• The underside of the tongue, near the tip, where a cluster of small glands sits.
• The inner cheek, especially along the bite line.
• The roof of the mouth. A mucocele on the roof of the mouth is usually the "superficial" type: one or more tiny, clear blisters on the soft palate or the back of the hard palate that burst within a day or so and leave a small raw spot. They can come back over and over, sometimes after meals, and they're more common in people who have oral lichen planus.

The upper lip is a different story. Mucoceles there are uncommon. A bump inside the upper lip is more likely than a lower-lip bump to be a small salivary gland tumor, so we want to see those.

Bump on the inside of your lip? Here's how to sort it out

A bump on the inside of the lip is one of the most common reasons people call us, and a clear bump on the inside of the lip after a recent bite is very often a mucocele. A few questions help narrow it down:

• Is it soft and filled with fluid? A soft, clear or bluish bump on the lower lip inside, especially one that has popped and refilled, points to a mucocele.
• Is it firm and the same color as your lip? A firm, smooth, pink bump that doesn't change is more likely an irritation fibroma (a small knot of scar tissue from repeated biting).
• Is it an open sore? A shallow, painful, white or yellow sore with a red ring is a canker sore, not a mucocele.
• Is it on the outside edge of your lip, with tingling and a cluster of tiny blisters? That "lip blister" is more likely a cold sore, which is contagious.
• Did it appear dark red or purple right after a bite or a hot or crunchy food? It may be a blood blister, which usually breaks and heals within a week or two.
• Is it on the upper lip, firm, or slowly getting bigger? Get it checked.

Tiny yellow-white dots on the inner lip that have always been there are usually Fordyce spots, which are normal oil glands.

Mucocele vs. other lip and mouth bumps

Here's how a mucocele compares with the things it's most often confused with.

Will a mucocele go away on its own?

Sometimes. Small mucoceles often break open, drain, and heal over a few weeks, especially if you can leave them alone. Many, though, follow a frustrating pattern: the bump pops, flattens for a day or two, and then fills right back up. Some go through that cycle for months.

A reasonable plan is to give a new mucocele two to four weeks. If it's still there after that, keeps coming back, is getting bigger, or is in the way when you eat or talk, it's time for an exam. A mucocele that has hung around for a long time can turn firm and scarred, and it's less likely to go away by itself.

Should you pop a mucocele?

No. It's tempting, and it looks like it would work. Here's why it doesn't:

• The gland is still feeding it. Draining the fluid doesn't fix the torn duct, so it usually refills within days. Aspirating mucoceles with a needle has a high rate of coming back, which is why it isn't a recommended treatment.
• You can make it worse. Pins, needles and fingernails carry bacteria into the tissue. Repeated picking adds scar tissue and can make the eventual removal bigger.
• It might not be a mucocele. A few other bumps look similar, and those shouldn't be cut into at home.

If it pops on its own, that's fine. Rinse with warm salt water and let it be.

How to get rid of a mucocele: what you can do at home

There's no cream or rinse that dissolves a mucocele. Home care is about giving a small one the best chance to heal and not re-injuring it.

1. Stop chewing on it. This is the big one. Most mucoceles come back because the same spot keeps getting bitten. If you catch yourself nibbling, try to break the habit.
2. Rinse with warm salt water (½ teaspoon of salt in a cup of warm water) a few times a day, especially if it has opened. Swish and spit.
3. Go easy with food. Skip very crunchy or sharp foods that can scrape it for a few days.
4. Check for a sharp edge. Run your tongue over the teeth near the bump. A chipped tooth, rough filling or bracket that keeps catching the lip needs to be smoothed.
5. Watch the calendar. Note when you first saw it. If it's still there after a few weeks, call us.

Oral mucocele treatment: what a dentist can do

When a mucocele doesn't go away, mucocele treatment is usually a quick procedure. We'll start by examining it, asking how long it's been there and whether it comes and goes, and looking for a tooth or appliance that keeps catching it. That's usually enough to know it's a mucocele.

Removing the mucocele and its gland

The standard oral mucocele treatment is to remove the bump together with the small gland or glands feeding it, under local anesthetic. Taking out the gland is the important part. If only the bubble is drained or cut off, the gland keeps leaking and the mucocele comes back. The tissue is sent to a lab to confirm what it is. A few stitches close the spot, and most people are back to normal eating within a few days. Mild numbness or a small firm area at the site can happen and usually settles.

Depending on the size and location, we may handle a straightforward lip mucocele or refer you to an oral surgeon we work with. Ranulas, mucoceles on the underside of the tongue, and larger or unusual lesions generally go to an oral and maxillofacial surgeon.

Other options in some cases

• Laser removal or vaporization. Some offices use a laser, which can mean little bleeding and no stitches. Studies comparing it with scalpel removal haven't shown a clear difference in how often mucoceles come back.
• Cryotherapy (freezing) or electrocautery, mainly for small or superficial lesions.
• Micro-marsupialization, often used for small mucoceles in children. A stitch is passed through the top of the bump and left for about a week so a new drainage path forms. It avoids cutting, but results vary and some come back.

Two recent reviews pooled the studies and found that recurrence rates with scalpel removal, laser and minimally invasive techniques are broadly similar, while the less invasive methods had fewer side effects such as nerve irritation. The best choice depends on the person, the size and location of the mucocele, and the clinician's experience.

Other ways we help

• Smooth a sharp tooth or filling, or adjust an appliance, so the lip stops getting bitten.
• Biopsy or refer anything that doesn't behave like a mucocele. Our oral medicine and diagnosis visits are set up for exactly this kind of question.
• Check the rest of your mouth at the same visit during a comprehensive exam.

Why does my mucocele keep coming back?

There are three usual reasons:

• The feeding gland is still there. Popping, draining or shaving off the top leaves the leaky gland behind.
• Neighboring glands get injured. The lip is packed with these glands, so a new one can be damaged next to the old spot.
• The habit continues. Lip biting, lip sucking, or a tooth edge that keeps catching the same place.

After complete removal that includes the gland, most mucoceles don't return, though a small number do, often because a neighboring gland gets injured.

Ranula: a mucocele under the tongue

A ranula is a mucocele on the floor of the mouth, under the tongue. Instead of coming from one of the tiny minor glands, it almost always comes from the much larger sublingual gland. Because that gland makes more saliva, ranulas tend to be bigger than lip mucoceles.

• What it looks like: a soft, painless, bluish, see-through swelling to one side under the tongue. Small ones look like a large blister. Big ones can push the tongue up and affect speech, chewing or swallowing.
• Who gets them: most often teenagers and young adults. Some babies are born with one.
• Plunging ranula: sometimes the saliva leaks down through the muscle of the floor of the mouth and shows up as a soft swelling in the upper neck, under the jaw, with or without a bump in the mouth. Some develop after an oral ranula was drained or only partly removed.
• Treatment: ranulas are treated by an oral and maxillofacial surgeon or an ENT. The most reliable fix is removing the sublingual gland along with the ranula. Simply draining it almost always leads to it coming back.

If you notice a swelling under your tongue, see us. Get care the same day if the swelling is growing quickly or makes it hard to swallow or breathe.

Is a mucocele dangerous or cancer?

A mucocele itself isn't cancer and doesn't turn into cancer. It's a leak of normal saliva. The overwhelming majority of soft, fluid-filled bumps on the lower lip are exactly what they look like.

The reason we still send removed tissue to a lab, and the reason we want to see some bumps sooner, is that a few other things can look similar. Salivary gland tumors, most of them benign, can form in the same small glands and occasionally look like a mucocele. Small salivary gland tumors of the lip turn up far more often in the upper lip than the lower, which is one more reason an upper-lip bump gets a closer look. Rarely, a cancer of a minor salivary gland has been reported to mimic a mucocele.

Signs that make a bump worth checking soon:

• It's on the upper lip, the palate, or the cheek and has no clear history of injury
• It feels firm or rubbery instead of soft
• It never pops or changes size, and it slowly grows
• It's painful, ulcerated, numb, or bleeds
• You're an older adult with a new bump and no history of biting the area

Most of these still turn out to be harmless, but a biopsy is the only way to know for sure. If you want to learn more about the warning signs we watch for, see our pages on signs of oral cancer and oral cancer screening.

Mucoceles in kids and teens

Most mucoceles happen in children, teenagers and young adults, and lip biting is the main reason. Kids with braces are especially prone because brackets press the lip against the teeth. Babies can occasionally be born with a ranula or develop a mucocele on the lip or tongue.

• If it's small and not bothering your child, it's fine to wait a few weeks and see if it goes away.
• Help them leave it alone. Kids poke at these constantly, which keeps them going.
• If it lasts, keeps returning, or gets in the way of eating or talking, bring them in. Treatment can be adjusted for a child's age and comfort, and some options, like micro-marsupialization, avoid cutting.
• Skip benzocaine numbing products for children under 2.

Mucoceles aren't a pregnancy concern. If one shows up while you're pregnant, it can usually wait until after delivery unless it's large or bothersome.

Can you prevent mucoceles?

You can't prevent every one, but you can lower the odds of a repeat:

• Work on lip biting or lip sucking habits, especially when stressed or concentrating.
• Get sharp edges fixed. Chipped teeth, rough fillings and poking orthodontic wires are easy for us to smooth. Ask your orthodontist for wax for any bracket that rubs.
• Wear a mouthguard for contact sports.
• Chew carefully, especially right after a dental visit while your lip is numb.
• Keep up regular checkups. See our home care instructions for everyday tips.

When to see a dentist about a mucocele

Mucocele FAQ

Related conditions

Sources

1. Huzaifa M, Soni A. Mucocele and Ranula. StatPearls. National Library of Medicine; updated 2023.
2. Hashemi M, Zohdi M, Zakeri E, Abdollahzadeh-Baghaei T, Katebi K. Comparison of the recurrence rate of different surgical techniques for oral mucocele: a systematic review and meta-analysis. Med Oral Patol Oral Cir Bucal. 2023;28(6):e614–e621.
3. Wang Q, et al. Evaluating the outcomes of minimally invasive therapy vs surgery for oral mucoceles: a systematic review and meta-analysis. J Evid Based Dent Pract. 2023;23(2):101841.
4. Patini R, et al. Tongue mucoceles: a retrospective clinic-pathological evaluation of 240 cases. BMC Oral Health. 2023;23(1):862.
5. Yih WY, Kratochvil FJ, Stewart JC. Intraoral minor salivary gland neoplasms: review of 213 cases. J Oral Maxillofac Surg. 2005;63(6):805–810.
6. U.S. Food and Drug Administration. Risk of serious and potentially fatal blood disorder prompts FDA action on oral over-the-counter benzocaine products. 2018.

This page is for general education and isn't a diagnosis. Every mouth is different. If you have a sore you're worried about, see your dentist or physician. Photos marked Wikimedia Commons are used under their listed licenses and may have been cropped or resized.