Oral health is more complicated than many people expect. If you’ve ever asked yourself, “Why does my tooth hurt?” you know just how sensitive the mouth, teeth, and gums can be. There are many issues that can cause discomfort in and around the gums, and some are more serious than others. This guide covers the most common causes of swollen gums and how to address each.
Common Causes of a Swollen Gum Around One Tooth
The most common cause of swollen gums is gingivitis, an early and reversible stage of gum disease that most adults will experience at least once in their lifetime1. Gingivitis often results from excessive plaque buildup that hardens into tartar, which irritates the gums and leads to swelling. Thankfully, it’s usually manageable with careful oral hygiene practices, such as brushing at least twice daily, flossing daily, and visiting the dentist for a dental cleaning about twice a year2.
Gingivitis often occurs around multiple teeth or throughout the entire mouth, but it can also be centered around individual teeth. Left untreated, gingivitis may progress to periodontitis, which demands more serious treatment.
It’s also possible for the gum around a single tooth to begin swelling due to irritation from food debris that gets stuck under the gum. Other types of irritation and accidental damage, like poking your gums with a toothpick, can cause swelling, too.
There are also more serious causes of localized swelling of the gums that should be promptly treated with extra care. The first of these concerns is a tooth abscess, which results from a bacterial infection and presents as a buildup of pus. Tooth abscesses can occur at the tip of a root (periapical abscess) or on the side of the tooth at the gumline (periodontal abscess)3. The other cause of localized swelling is known as pericoronitis, which is swelling around a wisdom tooth that is typically caused by impaction.
Is It a Wisdom Tooth?
If you’re experiencing localized swelling of the gums and find yourself asking, “Why is my gum swollen around one tooth in the back?” you may first want to determine whether a wisdom tooth is the root cause. If you’ve had all your wisdom teeth removed, this won’t be a concern for you.
Wisdom teeth typically come in during the teenage years and early 20s, in a process known as eruption. Sometimes, when the wisdom teeth erupt, they remain partially covered by the gum. A wisdom tooth that’s still covered this way is considered impacted, and the gum covering an impacted tooth can cause issues when food, debris, and bacteria get stuck beneath the gum and tooth, resulting in a swelling known as pericoronitis4.
Pericoronitis can cause several side effects, such as toothaches, fevers, halitosis, and significant swelling. It can be treated with a combination of antibiotics and cleaning the affected area, but it may recur. Sometimes, oral surgery is recommended to remove the offending gum flap and prevent future infections5.
Could It Be an Abscess?
Another concerning cause of localized swelling is an abscess. An abscess is the result of a bacterial infection, usually caused by an undiagnosed or improperly treated cavity. Abscesses can be painful and messy, as they produce a lot of swelling, emit pus, and are located close to the nerves and connective tissue surrounding and inside the affected tooth3.
If you’re experiencing moderate to severe pain or discomfort, bad breath, major swelling, or pus in and around the gums, or if your tooth hurts when chewing, it’s possible you have an abscess and should get it treated as soon as possible.
A tooth abscess may be treatable with a root canal, which involves removing the dental pulp in the affected area. If an abscess is too advanced, however, you may need to have the affected tooth removed6.
What to Do Right Now
If you’re experiencing any of the above symptoms, the first step is to schedule a visit with your dentist. Only your dentist can properly identify the issue and give you a treatment plan. In the meantime, it’s crucial to practice good oral hygiene. Make sure you brush your teeth for at least two minutes at least twice a day, though you can brush your teeth after every meal for extra coverage.
You should also floss once a day and, if possible, visit your dentist for a routine cleaning once or twice yearly. Sometimes, good dental hygiene isn’t enough, so talk to your dentist about long-term treatment plans to keep your mouth happy and healthy.
If you’re experiencing severe pain, suspect you have an abscess, or notice any signs of rot or decay, you should visit the emergency room or contact an emergency dentist for further help. At the emergency room, you aren’t likely to get full treatment, but they can help ensure your safety until a dentist can see you.
For minor but persistent swelling, it’s typically safe to visit your dentist when they have an opening. Swollen gum not going away? Let Beam Dental take a look—book a quick exam and get a clear diagnosis today.
Frequently Asked Questions
Will a swollen gum heal on its own?
A swollen gum generally won’t heal on its own. That’s because the most common causes of gum swelling are persistent conditions, such as gingivitis, periodontitis, and periocoronitis. Sometimes a piece of food stuck in the gum will cause swelling. When this is the case, removing the debris will help the swelling go down, but swelling that lasts more than a few hours is unlikely to heal on its own.
Should I go to the ER for a swollen gum?
Generally, you don’t need to visit the ER for a swollen gum. If you suspect you’re having a dental emergency, first try to visit an emergency dentist, as a general ER won’t be equipped to provide comprehensive dental treatment.
That said, if you’re experiencing an emergency, such as facial swelling and a fever, and you get in at an emergency dentist, a visit to the ER can still help you manage your symptoms while you wait to see the emergency dentist.
Can food get stuck under the gum cause swelling?
Yes, food that gets stuck under the gum is a common cause of swelling. This is one reason why flossing daily is important for dental health. If you have food stuck under your gums, try to remove it as soon as possible, as leaving it alone allows bacteria to grow, which can cause further issues. If you often find yourself asking, “Why does my tooth hurt?” it could be that you have debris stuck beneath the gum, causing irritation.
Sources:
- Mayo Clinic Staff. (16 November 2023). Gingivitis. Mayo Clinic. Retrieved March 25, 2026, from https://www.mayoclinic.org/diseases-conditions/gingivitis/symptoms-causes/syc-20354453
- (15 May 2024). Oral Health Tips for Adults. Centers for Disease Control and Prevention. Retrieved March 25, 2026, from https://www.cdc.gov/oral-health/prevention/oral-health-tips-for-adults.html
- Mayo Clinic Staff (29 June 2022). Tooth abscess. Mayo Clinic. Retrieved March 25, 2026, from https://www.mayoclinic.org/diseases-conditions/tooth-abscess/symptoms-causes/syc-20350901
- Key, A. (6 February 2025). Pericoronitis. WebMD. Retrieved March 25, 2026, from https://www.webmd.com/oral-health/pericoronitis
- (11 September 2022). Pericoronitis. Cleveland Clinic. Retrieved March 25, 2026, from https://my.clevelandclinic.org/health/diseases/24142-pericoronitis
- Sanders, J. and Houck, R. (20 February 2023). Dental Abscess. StatPearls. Retrieved March 25, 2026, from https://www.ncbi.nlm.nih.gov/books/NBK493149/
