A tooth abscess typically appears as a swollen, red bump on the gum filled with pus. It often looks like a pimple sitting right at the base of a tooth, and it may be white or yellowish at its center where the pus collects. But the visible signs don’t always start on the gums. In many cases, the first clue is the tooth itself changing color or swelling that spreads into the face and jaw.
What It Looks Like on the Gums
The most recognizable sign of a tooth abscess is a small, fluid-filled bump on the gum tissue near the affected tooth. Dentists call this a parulis, but most people know it as a gum boil. It forms where a drainage tunnel from the infected tooth root reaches the surface of the gum, typically appearing right at the line where the firm, pink gum tissue meets the softer tissue of the inner cheek.
This bump is usually red or dark pink around its edges, with a whitish or yellowish head where pus is pushing toward the surface. It can range from the size of a pinhead to roughly the size of a pea. If it ruptures on its own, you may notice a foul-tasting, salty fluid leaking into your mouth. The gum tissue surrounding the bump often looks puffy and inflamed, and the area may feel warm to the touch. Some abscesses drain intermittently, so the bump can shrink and then reappear over days or weeks.
Changes to the Tooth Itself
Before any bump appears on the gum, the tooth involved often changes color. When the soft tissue inside a tooth dies from infection or injury, the tooth loses its blood supply and begins to darken. It typically starts by turning a dull yellow, then shifts to gray, and can eventually turn almost black. This discoloration happens gradually and affects just the single tooth, making it stand out noticeably from its neighbors.
A darkening tooth doesn’t always mean an abscess has formed yet, but it signals that the inner tissue is dead or dying, which creates the conditions for infection. If you notice one tooth looking noticeably darker than those around it, especially paired with tenderness or sensitivity, that’s an early visual warning worth paying attention to.
When Swelling Spreads to the Face
An abscess that isn’t draining through the gum can push infection outward into the surrounding tissue. This creates visible swelling in the face, cheek, or neck on the same side as the affected tooth. The swelling may look lopsided, making one side of the face appear noticeably fuller than the other. The skin over the swollen area often looks tight and shiny and feels firm or hot.
Upper tooth abscesses tend to cause swelling under the eye or along the cheekbone. Lower tooth abscesses more commonly cause swelling along the jawline or under the chin. In severe cases, swelling can extend down into the neck or up toward the eye socket. If the swelling makes it difficult to breathe, swallow, or fully open your mouth, that’s a sign the infection has spread into deeper tissue and needs emergency care immediately.
Abscess vs. Canker Sore
People often confuse a gum abscess with a canker sore because both appear as small lesions inside the mouth. The differences are straightforward once you know what to look for.
- Canker sore: A small, shallow, open ulcer with a white, yellow, or grayish center and a flat red border. It sits on soft tissue like the inner cheek, lip, or tongue, not typically right at the gum line near a specific tooth.
- Abscess: A raised, swollen bump that looks red and inflamed with a pus-filled center. It appears on the gum tissue directly near or below a tooth, and it often feels firm rather than flat.
Canker sores are surface-level and heal on their own within a week or two. An abscess is a sign of deeper infection and will not resolve without treatment. If the bump is raised, sits near the root of a tooth, and produces any drainage, it’s far more likely an abscess than a canker sore.
Signs That Need Immediate Attention
Most abscesses develop slowly enough that you can get a dental appointment within a day or two. But certain visual and physical signs indicate the infection is spreading and requires urgent care. Facial swelling that worsens rapidly over hours, swelling that extends to the neck or under the jaw, or any difficulty breathing or swallowing are all red flags. A fever combined with visible facial swelling is another signal that the infection has moved beyond the tooth and into surrounding tissue.
The ADA and CDC guidelines classify an abscess with systemic involvement, meaning the infection is affecting your body beyond the mouth, as requiring urgent referral. If you can’t reach a dentist and you have a fever with worsening facial swelling, an emergency room visit is appropriate. Dental infections that spread into the deep spaces of the jaw and neck can become life-threatening, so visible swelling that’s getting worse rather than staying stable shouldn’t be waited out.