A swollen spot on the top of your gum is almost always caused by one of a handful of common problems: a buildup of bacteria along the gumline, a trapped piece of food, an abscess, or irritation from a tooth trying to push through. Most cases are mild and resolve within a few days, but some signal an infection that needs professional treatment. The location, timing, and accompanying symptoms can help you narrow down what’s going on.
Gum Disease: The Most Common Cause
The single most frequent reason for swollen gums is the early stage of gum disease, called gingivitis. It starts when plaque, a sticky film of bacteria, builds up on your teeth and isn’t fully removed by brushing and flossing. That plaque hardens into tartar, which irritates the gum tissue and triggers inflammation. The result is gums that look red, feel puffy or tender, and bleed easily when you brush.
Gingivitis is reversible with better oral hygiene, but if it progresses, it becomes periodontitis, a more serious infection that damages the bone supporting your teeth. At that point, gums may pull away from the teeth, pockets form between the gum and tooth, and chewing can become painful. In advanced cases, teeth loosen or need to be removed. If your swelling is limited to one area along the top of your gumline and you’ve been inconsistent with flossing, localized plaque buildup is the likeliest explanation.
Something Stuck Under the Gumline
A surprisingly common culprit is a small piece of food, especially popcorn husks, seed shells, or meat fibers, wedged beneath the gum. The thin, rigid edge of a popcorn kernel shell can slide under the gum margin and resist normal brushing or rinsing. Once lodged there, it breaks the natural seal between the gum and tooth, and your immune system responds by flooding the area with blood flow, producing redness, warmth, and swelling.
The telltale sign is a sharp or scratchy feeling in one specific spot, along with localized tenderness when eating or touching the area. You might also feel pressure between teeth or notice an unpleasant taste. If the debris stays trapped for more than a day or two, the swelling gets puffier, a dull ache sets in, and you may see minor bleeding when brushing near the site. Gentle flossing can often dislodge the fragment. If it doesn’t come free and the swelling persists, a dentist can remove it quickly.
Dental Abscess
If the swelling is a distinct, painful bump that feels like it’s filled with pressure, it may be an abscess. There are two main types. A periapical abscess starts inside the tooth, usually from an untreated cavity or crack that lets bacteria reach the nerve, and the infection drains out through the root into the gum above it. A periodontal abscess forms directly in the gum tissue, often in a deep pocket between the tooth and gum where bacteria have been trapped.
Both types typically cause a throbbing pain that doesn’t let up, a bad taste or foul smell from pus draining in your mouth, and sensitivity to hot or cold. Abscesses don’t resolve on their own. The infection needs to be drained and the source treated, whether that means a filling, root canal, or deep cleaning of the gum pocket. Left alone, the bacteria can spread beyond the mouth.
Wisdom Teeth and Pericoronitis
If the swelling is toward the back of your upper jaw, a partially erupted wisdom tooth is a strong possibility. When a wisdom tooth only breaks partway through the gum, it leaves a flap of tissue draped over part of the tooth. That flap traps food particles and bacteria in an area you can’t easily clean, creating an ideal environment for infection. This condition is called pericoronitis.
Milder cases cause a painful, swollen gum flap near the back tooth, difficulty biting down without hitting the inflamed tissue, and a bad taste or smell. More severe episodes bring swelling in that side of the face, swollen lymph nodes under the jaw, and muscle spasms that make it hard to open your mouth fully. Pericoronitis tends to flare up repeatedly until the wisdom tooth either fully erupts or is extracted.
Hormonal Changes
Hormones can make your gums dramatically more reactive to the same amount of plaque that wouldn’t have bothered them before. During pregnancy, rising progesterone increases blood flow throughout the body and makes gum tissue more sensitive to bacteria. The immune system also overreacts to plaque during pregnancy, amplifying inflammation and bleeding beyond what the amount of plaque alone would cause. This is common enough that it has its own name: pregnancy gingivitis.
The same pattern occurs during puberty, while taking hormonal birth control, and around menopause. In each case, the gum swelling is typically temporary and tied to the hormonal shift, but it still requires attention. Plaque that would cause mild irritation under normal hormonal conditions can trigger significant swelling during these periods.
Medications That Cause Gum Overgrowth
Certain medications cause gum tissue to physically enlarge, a side effect called gingival overgrowth. Three drug classes are the main offenders: seizure medications, blood pressure medications in the calcium channel blocker family, and immunosuppressants used after organ transplants. Among blood pressure drugs, nifedipine causes the most overgrowth, affecting roughly 38% of people who take it. Other calcium channel blockers carry lower but still notable risk, ranging from about 3% to 20% depending on the specific drug.
This type of swelling looks different from infection. The gums gradually become firm and enlarged, sometimes growing over part of the tooth surface. It’s not typically painful or red in the way that an infection would be. If you’ve recently started a new medication and noticed your gums changing, that connection is worth raising with your prescriber. Adjusting the medication often improves the overgrowth, though it can take time to reverse.
What You Can Do at Home
For mild swelling without severe pain or fever, a salt water rinse is a reasonable first step. Dissolve half a teaspoon of salt in one cup of warm (not hot) water and swish gently for 30 seconds. This helps draw out fluid from swollen tissue and creates an environment less hospitable to bacteria. You can repeat this two to three times a day.
Gentle but thorough brushing and flossing around the swollen area is important even though it may be uncomfortable. Avoiding the area lets more plaque accumulate and makes the problem worse. A soft-bristled toothbrush reduces irritation while still cleaning effectively. If you suspect food is trapped, careful flossing or a water flosser can help dislodge it.
Signs You Need Prompt Care
Some symptoms mean the swelling has moved beyond what home care can handle. Fever paired with dental pain suggests an infection that may be spreading beyond the original site. Swelling in the face or jaw, not just the gum, points to a deeper infection. Pus draining from the gum, difficulty opening your mouth, swollen lymph nodes, or pain that keeps you from sleeping all warrant a call to your dentist rather than a wait-and-see approach. An untreated dental infection can spread to surrounding tissues and, in rare cases, become a serious systemic problem.
Even without those red flags, gum swelling that hasn’t improved after a week of consistent home care is worth having examined. A dentist can measure the depth of the space between your gum and tooth to determine whether you’re dealing with simple inflammation or something more advanced, and can spot problems like a hidden crack or trapped debris that you wouldn’t be able to identify on your own.