- Swelling at one tooth means a local cause, not gum disease.
- Whether the tooth is alive or dead decides the treatment.
- A live tooth points to a gum pocket infection.
- A dead tooth points to an infection at the root tip.
- Food or a floss shred trapped under the gum is a real cause.
- Swelling that drains and settles has not healed.
- Facial swelling or fever means the same day, not next week.
What causes swelling around a single tooth
- A periodontal abscess. Infection trapped in a deep gum pocket beside the tooth.
- A periapical abscess. Infection at the root tip of a tooth whose nerve has died.
- Something trapped under the gum. A popcorn hull, a seed, a shred of floss.
- Pericoronitis. Inflammation under the gum flap over a partly erupted wisdom tooth.
- A cracked tooth, letting bacteria track down the fracture line.
- A failing filling or crown with a leaking margin.
- Recent dental work irritating the tissue temporarily.
- A burn or injury from hot food, a toothpick or aggressive brushing.
These are the ones that put swelling at a single site. Generalized puffiness across several teeth is gum inflammation rather than a localized infection, and it has a different set of causes.
For scale, periapical abscesses make up 14% to 25% of acute orofacial infections seen in general practice, pericoronitis 10% to 11%, and periodontal abscesses 6% to 7%.
The test that decides the treatment
Both abscesses cause a red, tender, swollen gum at one tooth. Both can produce pus and a bad taste. One is fixed with a deep clean, the other with a root canal.
The tooth's nerve tells you which.
A tooth with a periodontal abscess is alive. It responds normally to cold, because the problem sits in the gum beside it rather than inside it.
A tooth with a periapical abscess is dead or dying. Cold gives no response, or a strange lingering ache.
Other clues that point at the nerve:
- Pain that woke you at night before the swelling appeared
- The tooth has a large filling, a crown, or a history of trauma
- The tooth looks darker than its neighbours
- Pain on biting down
Clues that point at the gum pocket:
- The tooth is otherwise healthy with no big restorations
- You have bleeding gums elsewhere
- The swelling came up fast, over a day or two
- Pressing the gum releases pus at the gumline
Lingering sensitivity to heat and a bad taste are the classic root canal infection symptoms that come with a dying nerve.
Food, floss, and other trapped things
A periodontal abscess can start from a foreign object, including a piece of dental floss pushed under the gum.
Popcorn hulls are the classic. So are seeds, fish bones, and a shred of floss left behind after a snag.
The pattern is specific:
- It started within a day or two of a particular meal
- The swelling is on one side of one tooth
- It feels tight and pressured rather than throbbing
- Flossing that spot produces a smell
Gentle flossing sometimes releases it. Do not dig with anything sharp. If a day of careful cleaning does not settle it, a hygienist can flush the pocket in minutes.
Wisdom teeth and the gum flap
Swelling around a partly erupted wisdom tooth is its own thing. The gum flap over the tooth traps food and bacteria underneath, and the opposing tooth bites onto the swollen flap and makes it worse.
The symptoms are distinctive: pain towards the back of the jaw, difficulty opening wide, a bad taste, and sometimes swelling of the cheek on that side.
This one flares and settles and flares again. Each flare tends to be worse than the last.
What to do tonight
These only get you comfortable until you are seen.
- Rinse with warm salt water several times a day. It soothes the tissue and helps clear debris.
- Ibuprofen with acetaminophen works better than either alone for dental pain, following the labels.
- Cold compress on the outside of the cheek, 20 minutes at a time.
- Keep brushing the area, gently. Leaving it alone makes it worse.
- Sleep with your head raised.
- Skip heat on the face while there is swelling.
Do not push anything sharp into the swelling, and do not try to lance it. Do not take leftover antibiotics from a previous prescription. There are no over-the-counter antibiotics for a tooth infection in the US, and the ones behind the pharmacy counter do not remove the source anyway.
When it becomes an emergency
Go to an emergency room now if you have:
- Swelling spreading into your face, jaw, or neck
- Swelling reaching your eye, or closing it
- Difficulty swallowing, breathing, or opening your mouth
- Fever alongside facial swelling
- A racing heart, confusion, or feeling severely unwell
Call a dentist for a same-day appointment for swelling with throbbing pain, pus, a bad taste, or a tooth that hurts to bite on.
There is one trap here. If a gum boil appears and bursts, the pressure drops and the pain eases, and it feels like the problem has resolved. It has not. The abscess found an exit and the source is still there.
"Whatever is there stays where it is. It's localized. It's not spreading or moving anywhere else in the body,” says Dr. Chanelle Small, an endodontist and owner of Midtown Endodontics in New York. “That's why when you get swollen, it's right there. It depends on which tooth it is, but it is localized to the tooth."
That localization is useful. It means the tooth causing it can be identified, and it means treating that one tooth resolves it.
What the treatment involves
For a periodontal abscess: drainage, then mechanical debridement of the pocket. Antibiotics are reserved for immunocompromised patients or signs of spread rather than given routinely.
For a periapical abscess: root canal treatment to remove the dead pulp, or extraction. Drainage first if there is pressure.
For a trapped foreign body: flushing the pocket and removing it.
For pericoronitis: cleaning under the flap, and a conversation about whether the wisdom tooth stays.
Most of these are one appointment. The pain usually drops within a day of drainage.
Sources
- Periodontal Abscess. StatPearls, NCBI Bookshelf: https://www.ncbi.nlm.nih.gov/sites/books/NBK560625/
- Herrera D, et al. Acute periodontal lesions and endo-periodontal lesions. Journal of Periodontology, 2018: https://aap.onlinelibrary.wiley.com/doi/10.1002/JPER.16-0642
- Dr. Chanelle Small, DDS, endodontist, Midtown Endodontics. Recorded interview, 1 September 2026: https://www.midtownendodontics.com/meet-dr-small/
FAQ
Why is my gum swollen around one tooth but it does not hurt?
Painless swelling at one tooth often means a chronic infection that has found a drainage route, so pressure never builds. It is still an active infection and it still needs treating. A dead tooth can also stop hurting once the nerve has died completely.
How do I know if it is a gum abscess or a tooth abscess?
Whether the tooth responds to cold. A tooth with a gum pocket infection responds normally. A tooth with an infection at the root tip usually gives no response, because the nerve has died. A dentist tests this in seconds.
Can swollen gums around one tooth heal on its own?
The swelling can go down, especially if it drains. The cause does not resolve without treatment. Bone loss around the root continues in the meantime, which makes eventual treatment harder.
What if food is stuck under my gum?
Gentle flossing sometimes releases it. Never use anything sharp. Trapped objects, including a shred of floss, are a documented cause of gum abscesses, and a hygienist can flush the pocket quickly.
How long does a swollen gum around one tooth take to go down?
With treatment, usually a day or two after drainage. Without treatment, it may settle on its own and return, often worse.
Should I take antibiotics for a swollen gum?
Only if a dentist decides you need them. Guidance reserves antibiotics for immunocompromised patients or infection that has spread, because drainage and cleaning are what resolve the problem.
Bera edits this library at 1flowww: the question each article answers, the sources it cites, and the update history that shows what changed. Every clinical claim is reviewed by Dr. Kahng before it publishes. About the editor
Dr. Joyce Kahng is a cosmetic dentist, veneer expert, and the founder of Orange + Magnolia Dental Studio in Costa Mesa, CA. With 16+ years in practice and a following of 1.5M+ across Instagram, TikTok, and YouTube, she's known for making dentistry actually make sense. She's been featured in Forbes, Vogue, Allure, Glamour and GQ, and is the creator of the VeneerLIFT™.
Our editorial process · written by the editorial team, medically reviewed by a dentist, corrected in the open.
- 14 Dec 2024 Published. Clinical review by Dr. Joyce Kahng, DDS.
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