Pericoronitis (Wisdom Tooth Infection)
If the gum at the very back of your mouth is puffy, sore, and leaving a bad taste, and you're somewhere between your late teens and your thirties, there's a good chance it's pericoronitis. It's an infection of the small flap of gum that partly covers a wisdom tooth that hasn't fully come in. We see it all the time. It's very treatable, though it has a habit of coming back.
Pericoronitis is an infection of the gum flap (operculum) over a partly erupted tooth, usually a lower wisdom tooth. Trapped food and bacteria make the gum sore and swollen, often with a bad taste. It isn't contagious. Mild flares often calm down in a few days with rinsing and cleaning, but they tend to return. See a dentist soon. Facial swelling, fever, or trouble swallowing means same-day care.
Not sure this is what you have? Answer five quick questions in our mouth spot checker. It compares what you see with more than 40 common conditions and tells you how soon to have it looked at.
- What pericoronitis looks like
- Pericoronitis vs. a tooth abscess or dry socket
- Sore throat or stiff jaw? Other causes
- What causes pericoronitis?
- Symptoms of a wisdom tooth infection
- How long does pericoronitis last?
- How to treat pericoronitis at home
- Over-the-counter options
- Pericoronitis treatment at the dentist
- Does the wisdom tooth need to come out?
- Preventing another flare-up
- Special situations
- Is pericoronitis dangerous?
- When to see a dentist
- FAQ
What pericoronitis looks like
Look in a mirror with a flashlight, or have someone look for you, at the gum just behind your last molar. With pericoronitis you'll usually see:
- A wisdom tooth that's only partly through the gum. You might see one or two cusps, or just a small white spot.
- A flap of gum lying over the back part of the tooth. Dentists call it the operculum.
- That flap looking red, shiny, and puffy, sometimes with tooth marks on it from the upper tooth biting down.
- Sometimes a bit of pus or a bad-tasting fluid when you press near it.
It's often hard to see well because it's so far back, and the swelling can make opening wide uncomfortable. A swollen gum behind a wisdom tooth that's tender to the touch is the classic sign.
Here's what's going on underneath that flap:
Pericoronitis vs. a tooth abscess or dry socket
Pain in the back of the jaw has a short list of usual suspects. The timing and where the swelling sits usually sort them out, but an exam and an x-ray settle it.
| Pericoronitis | Tooth abscess | Dry socket | |
|---|---|---|---|
| What it is | Infected gum flap over a tooth that's still coming in | Infection at the root tip or in the gum next to a tooth | Lost or broken-down blood clot after a tooth is pulled |
| Where | Gum behind or over the last molar | Any tooth, often one with a deep cavity, crack, or old filling | An extraction site |
| When it starts | Any time while the wisdom tooth is partly erupted, often during a cold, stress, or a busy stretch | Often after a long-standing cavity or a cracked tooth | 2 to 4 days after an extraction |
| Typical feel | Sore, swollen gum, bad taste, hurts to bite or open wide | Deep throbbing tooth pain, tooth tender to tap, a gum boil | Severe pain that gets worse instead of better, often up to the ear |
| What you see | Red, puffy flap over a partly visible tooth | A pimple-like bump on the gum, or facial swelling | An empty-looking socket, sometimes with visible bone |
| Usual fix | Clean under the flap, then often remove the tooth if it keeps happening | Root canal or extraction, plus drainage if needed | A soothing dressing in the socket |
Read more about a tooth abscess or dry socket if one of those columns sounds more like you. Gum inflammation that runs along many teeth, rather than one back corner, is more likely gingivitis.
Sore throat or stiff jaw? Other causes to rule out
Pericoronitis often doesn't feel like a tooth problem at all. Lower wisdom teeth sit right next to the muscles that open your jaw and close to the throat, so a lot of people first think they have a sore throat or a jaw joint issue.
| Condition | Clues that point to it |
|---|---|
| Pericoronitis | Pain on one side at the very back, a swollen gum flap you can see or feel, bad taste, hurts to bite on that side. Jaw stiffness comes from swelling near the chewing muscles. |
| Sore throat or tonsillitis | Pain in the middle or both sides of the throat, red or swollen tonsils, often with a cold or fever. The gums look normal. |
| Upper wisdom tooth biting the gum | A sore, bruised spot on the lower gum flap where the upper tooth lands. This can happen without infection, but it often kicks one off. |
| Jaw joint or muscle pain (TMD) | Ache in front of the ear or in the cheek muscles, clicking, worse with chewing or clenching. No gum swelling. See our page on TMJ and TMD treatment. |
| Trismus after radiation | Jaw opening that slowly tightens over months after head and neck radiation, from scarring in the muscles. It's not an infection and needs a different plan. Read about radiation-induced trismus. |
What causes pericoronitis?
Wisdom teeth are the last teeth to come in, usually between about 17 and 25. Many of them don't have quite enough room. When a tooth gets partway through and stalls, a flap of gum is left over the back of it.
The space under a wisdom tooth gum flap is warm and dark, and you can't reach it with a toothbrush. Food packs in, the bacteria that normally live in the mouth multiply, and the gum reacts with swelling and infection. The bacteria involved are mostly the kind that thrive without oxygen, which is part of why it tastes and smells bad.
Things that make it more likely
- A wisdom tooth that's partly erupted and sitting upright. Studies find upright (vertical) lower wisdom teeth that are near the gum surface have the highest rates. Teeth buried deep in bone rarely cause it, because there's no opening to the mouth.
- An upper tooth that bites on the flap. Every bite bruises the swollen gum, which swells more, which gets bitten more.
- Being run down. Flare-ups often show up with a cold, stress, exams, poor sleep, or around a menstrual period.
- Lower resistance to infection, such as uncontrolled diabetes or medicines and treatments that weaken the immune system.
- Plaque buildup in the back of the mouth.
Pericoronitis isn't caused by anything you did wrong. The shape of the gum over the tooth is the real problem.
Symptoms of a wisdom tooth infection
Symptoms range from a mild ache that comes and goes to a lot of swelling. Common ones:
- Pain and tenderness in the gum behind the last molar, usually on one side
- A swollen gum flap that hurts when you bite down
- Bad taste or bad breath, sometimes pus
- Pain that spreads toward the ear, throat, or the angle of the jaw
- Trouble opening your mouth all the way (trismus)
- Pain when swallowing
- Tender, swollen glands under the jaw
- Swelling of the cheek or along the jaw, and fever, in more serious cases
Dentists sometimes describe it as acute, a sudden, painful flare, or chronic, a mild, nagging soreness and bad taste that hangs around on and off for months. Chronic cases can flare into acute ones.
How long does pericoronitis last?
A mild flare usually starts to settle within a few days once the area is being cleaned well, and it's often gone in about a week. A worse infection that needs a dental visit and sometimes antibiotics can take a bit longer to fully calm down.
The harder truth is that the flap is still there after the pain goes away. As long as the tooth stays partly covered, food and bacteria can collect again. Many people get a flare every few months, or every time they get sick or stressed. A tooth that's still coming in with enough room may eventually erupt fully, and the problem stops. A tooth that's stuck usually doesn't.
How to treat pericoronitis at home
Home care can calm a mild flare and keep you comfortable until you see us. It doesn't take the flap away, so plan on a dental visit too, especially if this is your first episode or it keeps coming back.
The first 1 to 3 days
- Rinse with warm salt water. Stir ½ teaspoon of salt into a cup of warm water. Swish hard around the back of the mouth for 30 seconds and spit. Do it after every meal and before bed.
- Flush under the flap. If you have a curved-tip plastic syringe (the kind given after wisdom tooth surgery), fill it with warm salt water and gently aim it under the flap. A water flosser on its lowest setting also works.
- Brush the area, gently. Use a soft brush, or a small single-tuft brush, and clean the back tooth and the flap edge. It'll be tender. Cleaning it is what helps it heal.
- Control the pain. Ibuprofen (Advil, Motrin) helps with both pain and swelling. Acetaminophen (Tylenol) is an option if you can't take ibuprofen. Follow the label.
- Use cold, not heat, on the outside. A cold pack on the cheek, 15 minutes on and 15 off, can ease swelling. Don't put a heating pad on a swollen face.
Until it settles
- Chew on the other side, and stick with soft foods like eggs, pasta, yogurt, soup, and smoothies.
- Avoid popcorn, chips, nuts, and seeds. Hulls and shards wedge under the flap.
- Drink plenty of water. If smoking or vaping is part of your day, this is a good week to stop; both slow healing.
- Call us if it isn't clearly better in 2 to 3 days, or sooner if it's getting worse.
Things not to do
- Don't hold aspirin against the gum. It burns the tissue.
- Don't try to cut, pop, or pick at the flap. You'll make it bleed and swell more, and you can push the infection deeper.
- Don't take leftover antibiotics. Most mild flares don't need them, and the wrong drug or a short course can make a later infection harder to treat.
Over-the-counter options
None of these will cure pericoronitis, but they can get you through a flare.
| Type | What it does | Things to know |
|---|---|---|
| Ibuprofen (Advil, Motrin) or naproxen (Aleve) | Eases pain and swelling | Take as the label directs, with food. Check with your doctor first if you have kidney disease, stomach ulcers, take blood thinners, or are pregnant. |
| Acetaminophen (Tylenol) | Pain relief | Gentle on the stomach. Don't go over the daily limit on the label, and watch for acetaminophen in cold medicines too. |
| Numbing gels (benzocaine, such as Orajel) | Brief numbing of the gum surface | Only lasts a short while and doesn't reach under the flap. Do not use benzocaine in children under 2. The FDA warns it can cause a rare but dangerous blood condition (methemoglobinemia). |
| Alcohol-free antiseptic mouthwash | Helps keep bacteria down | Swish and spit. Alcohol rinses sting inflamed gums. |
| Oxygenating rinse (hydrogen peroxide diluted to about 1.5%) | Cleans and may freshen the bad taste | Use as the label directs for a few days. Don't swallow it, and don't use full-strength peroxide. |
| Curved-tip irrigation syringe or water flosser | Flushes food out from under the flap | Use warm water or salt water on a low setting. Gentle is enough. |
For children and teens, use the children's or junior product and dose by weight or age as the label directs.
Pericoronitis treatment at the dentist
Most of what fixes a flare happens in the chair, and it's usually quick.
- Exam and x-ray. We look at the gum, check for spreading swelling, and take an x-ray to see the position of the tooth, the room it has, and the health of the tooth in front of it. If the tooth may need to come out and the roots sit near the nerve, a panoramic image or a 3D scan helps plan it. Read about our digital and 3D imaging.
- Clean under the flap. After numbing the area if needed, we gently flush and clean the pocket and drain any pus. This alone gives a lot of people fast relief.
- Take pressure off the flap. If the upper wisdom tooth is biting into it, we can smooth that tooth's edge, or recommend removing the upper tooth, which is often a simple extraction.
- Prescription rinse. A chlorhexidine rinse (a prescription in the US) helps keep the area clean for the next week or two.
- Antibiotics only when they're needed. If the infection is spreading, with fever, swelling in the face or neck, swollen glands, or a stiff jaw, we prescribe an antibiotic along with cleaning. For a mild, local flare, cleaning works and antibiotics usually don't add much.
- A plan for the tooth. Once the flare settles, we talk about whether to keep watching it or take it out.
Pericoronitis treatment is the same whether you're a regular patient or just walked in hurting. If it's flared up and you need to be seen quickly, see our emergency dental care page.
Does the wisdom tooth need to come out?
Not always, and not necessarily on the first episode. UK national guidance has long said that one mild episode of pericoronitis isn't a reason to remove a wisdom tooth on its own, but that a second or later episode is a fair reason to.
In real life, the deciding questions are:
- Will the tooth finish coming in? If there's room and it's upright, it may erupt fully and the flap goes away. We'll often watch it.
- Is it stuck? A tooth that's tilted or blocked by bone or the tooth in front won't come in further. The flap won't go away, and flares tend to keep coming.
- Is it hurting anything else? Decay or bone loss on the back of the 12-year molar in front of it tips the decision toward removal.
- How often, and how bad? One mild flare in five years is different from three flares this year, or one that spread.
Being honest about it: if pericoronitis keeps coming back, removing the tooth is usually what stops it. Depending on how the tooth sits and how close it is to the nerve, we may remove it here or refer you to an oral surgeon. For some deep lower wisdom teeth very close to the nerve, a surgeon may suggest a coronectomy, which removes the crown and leaves the roots in place.
Some offices remove just the gum flap (an operculectomy). It can work for a tooth that's upright with room to spare. The flap often grows back, though, especially when the tooth has no room, so we don't count on it as a permanent fix. Our blog post on wisdom teeth covers removal in more detail. If an extraction is part of your plan, you can look over our extraction aftercare instructions ahead of time, and if you're nervous about the procedure, ask us about sedation options.
Preventing another flare-up
- Clean behind the last tooth every day. A single-tuft brush or a toothbrush angled behind the molar reaches the flap edge.
- Rinse or flush after meals while the wisdom tooth is still partly covered.
- Get the wisdom teeth checked in the late teens. An x-ray then shows whether they have room to come in. Regular comprehensive dental exams make this part of the routine.
- Treat the first flare early, before it spreads.
- Plan ahead if you have a wisdom tooth that's flared before and a big trip, a pregnancy, surgery, or cancer treatment coming up. A flare is much easier to deal with at home than abroad.
Special situations
Teens
Wisdom teeth are the usual culprit, but the gum over a 12-year molar that's still coming in can also get irritated in younger kids. It's usually mild and settles with brushing and salt-water rinses. Bring your child in if the gum is very swollen, they have a fever, or they can't open their mouth normally.
Pregnancy
Pregnancy hormones make the gums more reactive, so a wisdom tooth that's never bothered you may flare. Don't wait it out. Dental exams, needed x-rays, and local numbing are considered safe during pregnancy. Acetaminophen is usually the pain reliever of choice; ask your obstetrician before taking ibuprofen or naproxen, since these are generally avoided from about 20 weeks on. If the tooth needs to come out, we'll talk with you and your obstetrician about timing.
Head and neck cancer treatment
Wisdom teeth that are partly erupted or have flared before should be looked at before radiation starts. Removing a lower tooth after radiation to the jaw carries a risk of poor bone healing (osteoradionecrosis), so it's much easier to deal with beforehand. If you're about to start treatment, see our page on dental care for head and neck cancer.
Bone-strengthening medicines, diabetes, and a weak immune system
If you take or have taken medicines for osteoporosis or cancer that affects bone, tell us before any extraction. Read more on osteoporosis medications and your dental health. People with uncontrolled diabetes, those on chemotherapy, and transplant patients can see an infection spread faster, so we'd rather see you early. More on diabetes and your mouth.
Is pericoronitis dangerous? Can it spread?
Most pericoronitis stays right where it started and clears with cleaning. Rarely, the infection spreads into the spaces of the cheek, under the jaw, and in the neck. Spreading infection under the tongue and jaw (Ludwig's angina) can swell enough to affect swallowing and breathing, and that is a medical emergency. Prompt care makes this unlikely, so knowing the warning signs is what matters.
When to see a dentist about pericoronitis
Make an appointment if:
- This is your first episode of a sore gum behind a wisdom tooth
- It isn't clearly better after 2 to 3 days of home care
- It keeps coming back, even if each flare is mild
- You notice a cavity, food packing, or soreness in the molar right in front of the wisdom tooth
- You have treatment coming up (radiation, chemotherapy, bone medicines, or a big surgery) and a wisdom tooth that has ever flared
Get care today if:
- Your cheek, jaw, or the area under your jaw is swelling
- You can't open your mouth much more than a finger's width
- You have a fever or feel sick overall
- Swallowing hurts a lot, or you're drooling
- You have diabetes, a weakened immune system, or are pregnant, and the gum is getting worse
Go to the ER or call 911 if you have trouble breathing, can't swallow your saliva, or swelling is spreading down your neck.
Pericoronitis FAQ
What is pericoronitis?
Pericoronitis is inflammation and infection of the gum around a tooth that's only partly through the gum, almost always a lower wisdom tooth. A flap of gum called the operculum covers part of the tooth, and food and bacteria get trapped underneath. The gum becomes sore and swollen, and you may notice a bad taste or trouble opening wide.
Is pericoronitis common?
Yes. It's one of the most common reasons young adults have pain in the back of the mouth. It shows up most often between ages 20 and 29, when wisdom teeth are coming in, and the lower wisdom teeth account for the large majority of cases. It's uncommon in children and in adults over 40.
What causes pericoronitis?
A wisdom tooth that only partly erupts leaves a flap of gum over the back of it. Food and the mouth's normal bacteria collect in the pocket under that flap, where a toothbrush can't reach, and the gum gets infected. An upper tooth biting on the flap, a cold, stress, poor sleep, and conditions that weaken the immune system can all set off a flare.
Is pericoronitis contagious?
No. Pericoronitis comes from bacteria that already live in your own mouth, trapped in a spot that's hard to clean. You can't catch it from someone or give it to anyone by kissing or sharing a drink.
Can pericoronitis go away on its own?
A mild flare can settle down by itself, especially with salt-water rinses and careful cleaning. The gum flap stays, though, so it often comes back. If the tooth is stuck and won't come in further, repeat episodes are likely, and removing the tooth is usually what ends them.
How long does pericoronitis last?
A mild flare usually improves within a few days of good cleaning and is often gone in about a week. A more serious infection that needs a dental visit and antibiotics can take longer to settle completely. If it isn't clearly improving after 2 to 3 days, or it's getting worse, see a dentist.
How do you treat pericoronitis at home?
Rinse with warm salt water after every meal, gently flush under the gum flap with a curved-tip syringe or a water flosser on low, and brush the area carefully with a soft brush. Ibuprofen or acetaminophen, taken as the label directs, helps with pain. Eat soft foods and chew on the other side. Home care can calm a mild flare, but you should still see a dentist, because it doesn't fix the flap.
How do you get rid of pericoronitis fast?
The fastest relief usually comes from a dentist cleaning and flushing the pocket under the gum flap and draining any pus. Many people feel better within a day or so of that visit. If an upper tooth is biting the flap, smoothing or removing that tooth helps too. The way to get rid of it for good is usually to remove the wisdom tooth if the problem keeps returning.
Do I need antibiotics for pericoronitis?
Not usually. Mild pericoronitis that stays at the gum responds to cleaning under the flap, rinses, and pain relievers. Antibiotics are for infections that are spreading, with fever, facial or neck swelling, swollen glands, or a stiff jaw. A dentist can tell which situation you're in.
Can pericoronitis kill you?
It's very rare. Nearly all pericoronitis stays in the gum and clears up with treatment. In uncommon cases the infection spreads into the spaces under the jaw and in the neck, which can make swallowing and breathing difficult and needs emergency care. Swelling under the jaw or in the neck, trouble swallowing or breathing, or a high fever means going to the ER right away.
Does pericoronitis mean my wisdom tooth has to come out?
Not always. After a single mild episode, many dentists will treat the flare and watch the tooth, especially if it has room to finish coming in. If pericoronitis keeps coming back, the tooth is stuck, or it's damaging the molar in front of it, removing it is usually recommended. It's the most reliable way to stop the flares.
Can the gum flap over a wisdom tooth be removed?
Yes. Removing the flap is called an operculectomy. It can help when the tooth is upright and has enough room to come in. The flap often grows back when the tooth is stuck or partly covered by bone, so removing the tooth is usually the more lasting option.
Can a wisdom tooth be pulled while it's infected?
It depends. Often the first step is to calm the infection with cleaning, rinses, and antibiotics if it's spreading, then remove the tooth once the swelling is down and you can open wide. In other cases, removing the tooth promptly is the quickest way to clear the infection. Your dentist or oral surgeon will decide based on how much swelling there is and how the tooth sits.
Sore gum behind a wisdom tooth?
If you're in the Jacksonville area and the back of your mouth is swollen, tender, or tastes bad, call or text us. We'll clean it out, get you comfortable, and talk through whether the tooth should stay or go.
Related conditions
Sources
- Pericoronitis. StatPearls. National Library of Medicine; updated 2022.
- Schmidt J, Kunderova M, Pilbauerova N, Kapitan M. A review of evidence-based recommendations for pericoronitis management and a systematic review of antibiotic prescribing for pericoronitis among dentists. Int J Environ Res Public Health. 2021;18(13):6796.
- Galvão EL, da Silveira EM, de Oliveira ES, et al. Association between mandibular third molar position and the occurrence of pericoronitis: a systematic review and meta-analysis. Arch Oral Biol. 2019;107:104486.
- National Institute for Health and Care Excellence. Guidance on the extraction of wisdom teeth (TA1). 2000.
- 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.