A tooth abscess typically appears as a swollen, pus-filled bump on the gum near the base of the affected tooth. It often looks like a small, reddish or yellowish-white blister, sometimes called a gum boil, and it may have a visible head similar to a pimple. But the visible bump on the gum is only one possible sign. An abscess can also change the color of the tooth itself, cause significant facial swelling, or drain as an open sore along the gumline.
The Gum Boil: The Most Recognizable Sign
The classic look of a dental abscess is a raised, pus-filled bump sitting on the gum tissue close to the root of a tooth. This bump, called a parulis or gum boil, is usually round or dome-shaped. It can range from the size of a small pea to roughly the size of a marble, and it tends to feel soft or fluid-filled when touched.
The color varies depending on how much pus has collected and how close it sits to the surface. A fresh or deep abscess may look red and inflamed, blending into the surrounding gum tissue. As pus builds up and pushes closer to the surface, the center often turns white or yellowish. Some gum boils eventually burst on their own, leaving behind an open, draining sore on the side of the gum that leaks a foul-tasting fluid. Even if the pain temporarily improves after draining, the underlying infection is still active.
Changes to the Tooth Itself
An abscess doesn’t always announce itself on the gum. Sometimes the first visible clue is the tooth changing color. When infection kills the nerve and blood supply inside a tooth (a condition called pulp necrosis), the tooth starts as yellow, then shifts to gray, and can eventually turn black. This darkening happens gradually, over weeks to months, and it stands out clearly against the surrounding teeth.
A single darkened tooth, especially one that has had a cavity or a crack, is a strong indicator that the tissue inside has died and infection may be brewing at the root, even if no bump has appeared on the gum yet.
Swelling Beyond the Gum
When a dental abscess progresses, the infection can push through bone and spread into the soft tissues of the face. At this stage the signs move well beyond the mouth. Swelling may appear in the cheek, along the jawline, or under the chin. In upper teeth, swelling can extend upward toward the eye area because the roots sit close to the maxillary sinuses, the large air-filled spaces behind your cheeks.
The swollen skin typically looks puffy and tight, feels warm to the touch, and may appear red or shiny. It can be tender even without pressing on it. Some people notice that one side of their face looks noticeably fuller than the other, and the swelling can worsen overnight when lying flat allows fluid to pool. If you develop a fever alongside facial swelling, or if you have any difficulty breathing or swallowing, that signals the infection has spread deeper into the jaw, throat, or neck and requires emergency care.
How It Differs From a Canker Sore
People sometimes confuse an abscess bump with a canker sore, but the two look and behave quite differently. A canker sore is a shallow, flat ulcer with a white or gray center and a red border. It sits on soft tissue like the inside of the cheek, the lip lining, or the tongue, and it isn’t associated with a specific tooth. It has no pus and no raised dome.
A gum boil from an abscess, by contrast, is raised, located directly on the gum near a tooth root, and filled with fluid. It often has a yellowish or whitish head. The easiest way to tell them apart: canker sores are open craters, while abscesses are filled bumps. Canker sores also aren’t tied to toothache pain, while an abscess typically comes with a severe, throbbing ache that radiates into the jaw, ear, or neck.
Signs That Are Easy to Miss
Not every abscess produces a dramatic gum boil or facial swelling. Some infections drain slowly through the bone and gum tissue without forming an obvious bump, creating only a small, persistent pimple-like spot that comes and goes. You might notice a bad taste in your mouth or mild tenderness around a tooth without seeing anything alarming in the mirror.
Other subtle signs include gum tissue that looks redder or puffier than normal around a single tooth, a tooth that feels slightly loose, or sensitivity to hot foods and drinks that lingers after you stop eating. In some cases, pressing on the gum near the root produces a small amount of discharge even when no visible bump is present. These quieter presentations are still active infections that can worsen over time, so a tooth that has been intermittently painful or sensitive deserves attention even if it doesn’t look like the textbook swollen abscess.
What the Stages Look Like Over Time
Dental abscesses tend to follow a progression you can track visually. In the earliest stage, you may see nothing at all. The infection is contained inside the tooth or at the tip of the root, and the only clue is pain or sensitivity. As the infection expands, pressure builds and the surrounding gum becomes swollen and red.
Next, a distinct bump forms on the gum as pus collects and pushes toward the surface. The bump grows, develops a white or yellow center, and may become increasingly painful. If untreated, it either bursts and drains (temporarily relieving pressure) or the infection spreads into the surrounding bone and soft tissue, causing the facial swelling described above. The tooth itself may darken during this process as the internal tissue dies. At any point in this timeline, the infection can flare, subside, and flare again, which is why an abscess that seems to “go away” on its own almost certainly hasn’t resolved.