A single swollen spot on your gums usually means something is irritating or infecting the tissue around one tooth. The most common cause is localized gum disease, where plaque buildup triggers inflammation in a specific area. But it can also point to an abscess, physical injury, trapped food, or something less obvious like a medication side effect. The good news: most causes are treatable, and many resolve quickly once you identify what’s going on.
Plaque Buildup and Localized Gum Disease
Gum disease, starting with gingivitis, is the single most common reason for swollen gums. It doesn’t always affect your whole mouth at once. Plaque, the sticky bacterial film that forms on teeth, tends to accumulate unevenly. If you’re missing a spot while brushing or flossing, that area can become inflamed while the rest of your gums look fine. You’ll typically notice redness, puffiness, and bleeding when you brush.
Left alone, gingivitis can progress to periodontitis, a deeper infection that damages the bone supporting your teeth. Dentists measure the depth of the space between your gum and tooth to assess this. Healthy gums measure 1 to 3 millimeters deep. Anything above 3 millimeters is a concern, and deeper pockets signal bone loss. At the gingivitis stage, though, the damage is fully reversible with better cleaning habits and a professional cleaning.
Abscess: Infection With a Pocket of Pus
If the swelling is painful, feels like a firm or squishy bump, and came on relatively fast, you may have an abscess. There are two main types. A periodontal abscess forms in the gum tissue itself, often when bacteria get trapped in a deep pocket beside a tooth. A periapical abscess forms inside the tooth’s innermost layer and spreads to the surrounding gum, usually from an untreated cavity or cracked tooth.
Both types can cause throbbing pain, sensitivity to hot or cold, a bad taste in your mouth, and sometimes a visible pimple-like bump on the gum that may drain. Abscesses don’t resolve on their own. They need professional drainage and often antibiotics. If you develop a fever, facial swelling, or difficulty breathing or swallowing, that’s a sign the infection is spreading into deeper tissues of the jaw, throat, or neck. This is a medical emergency, and you should go to an ER.
Something Stuck Under the Gumline
It sounds simple, but a popcorn hull, seed shell, or small piece of food wedged beneath the gumline is one of the most common triggers for sudden, localized swelling. The trapped debris irritates the tissue and creates a pocket where bacteria thrive. You might not even realize something is lodged there. Careful flossing or using an interdental brush can often dislodge the culprit, and the swelling typically goes down within a day or two once the irritant is removed.
Physical Injury or Aggressive Brushing
Sharp foods like chips or crusty bread can cut or scrape your gums. So can overly forceful brushing, snapping floss into the tissue, or a new orthodontic wire poking a spot. Minor gum injuries heal quickly, usually within 3 to 4 days. During that time, the area may look swollen and feel tender. If the injury becomes infected, healing takes longer. Rinsing with warm saltwater (1 teaspoon of salt in 8 ounces of warm water, swished for 15 to 30 seconds, up to four times a day) helps keep the area clean and reduces inflammation while it heals.
Braces, Dentures, and Oral Appliances
Orthodontic hardware creates extra surfaces where plaque can hide, especially around brackets and wires. This makes localized swelling common during treatment. Dentures that don’t fit well can rub against one area of the gums repeatedly, causing irritation and swelling in that spot. If you wear any oral appliance and notice persistent gum swelling, the fit or your cleaning routine around the device likely needs attention.
Hormonal Changes During Pregnancy
Rising levels of estrogen and progesterone during pregnancy increase blood flow to the gums and change how the tissue reacts to plaque. The result is pregnancy gingivitis, which can make gums swollen, sore, and prone to bleeding, sometimes more in one area than others. Symptoms can appear as early as the first trimester but tend to peak during the second or third trimester. The condition usually resolves after delivery, but keeping up with dental cleanings during pregnancy helps prevent it from worsening.
Medications That Cause Gum Overgrowth
Certain medications can cause gum tissue to physically enlarge, a condition called gingival overgrowth. The swelling isn’t from infection but from the drug stimulating excess tissue growth. Three drug classes are the main culprits:
- Anti-seizure medications: Phenytoin is the best-known offender. About half of the roughly 2 million people taking it develop some degree of gum overgrowth.
- Blood pressure medications (calcium channel blockers): Nifedipine causes gum changes in about 38% of users. Other drugs in the same class carry lower but still notable rates.
- Immune-suppressing drugs: Cyclosporine, commonly used after organ transplants, causes gum overgrowth in 13 to 85% of patients depending on the study.
Overall, roughly 40 to 50% of people taking any of these three drug types will experience some gum enlargement. The overgrowth can look like swelling around individual teeth, especially in the front of the mouth. If you’ve recently started one of these medications and notice your gums getting puffy, your dentist and prescribing doctor can discuss alternatives or management strategies.
Vitamin C Deficiency
Severely low vitamin C intake can lead to scurvy, which causes gums to become swollen, spongy, purple, and prone to bleeding. Teeth can even loosen. This is rare in developed countries but can happen in people with very restricted diets, certain digestive conditions, or heavy smoking (smokers need an extra 35 milligrams of vitamin C daily above the standard recommendation). Adults need 75 to 90 milligrams of vitamin C per day, an amount easily met by eating citrus fruits, bell peppers, strawberries, or broccoli regularly.
What to Do at Home While You Wait
Saltwater rinses are the simplest and most effective home measure for reducing gum swelling from most causes. Mix 1 teaspoon of salt into 8 ounces of warm water, swish for 15 to 30 seconds, and spit. You can repeat this up to four times a day and after meals. Gently brush the swollen area with a soft-bristled toothbrush rather than avoiding it, since plaque left on the inflamed tissue will only make things worse. Floss carefully around the affected tooth to check for trapped food.
If the swelling doesn’t improve within a few days, gets worse, or comes with significant pain, pus, fever, or facial swelling, that points to something that needs professional treatment. A simple exam and X-ray can usually identify the cause quickly.