A tooth abscess often shows up as a swollen, red or yellowish bump on the gum near the affected tooth. The tooth itself may darken to gray or black, and the surrounding gum tissue typically looks inflamed and puffy. Depending on how far the infection has spread, you might also notice swelling along your jaw or cheek.
The Gum Boil: The Most Visible Sign
The most recognizable sign of a tooth abscess is a small, raised bump on the gum called a parulis, commonly known as a gum boil. It forms when pus from the infected tooth root creates a drainage channel through the bone and gum tissue. The bump is smooth, sometimes slightly lumpy, and soft to the touch. It can appear yellow, red, or pink, and it may ooze a thick, yellowish fluid if you press on it lightly.
A gum boil typically shows up on the gum right next to the problem tooth, either on the outer (cheek-facing) side or along the inner gum line. It can range from a few millimeters to roughly the size of a pea. Some people mistake it for a canker sore, but a gum boil tends to be rounder, more raised, and located right at the gum line rather than on the soft tissue of the lip or cheek. It may come and go as pressure from the infection builds and then drains, which sometimes tricks people into thinking the problem has resolved. It hasn’t. The underlying infection is still active even when the bump temporarily shrinks.
Changes to the Tooth Itself
An abscessed tooth doesn’t always look different from the outside, but when it does, the change is usually in color. A tooth with a dead or dying nerve (the pulp inside) can gradually turn gray, dark brown, or even black. This happens because the blood supply inside the tooth breaks down, and the tissue essentially dies. The discoloration tends to be subtle at first, often looking like the tooth is just slightly darker than its neighbors, then becoming more obvious over weeks or months.
You might also see a visible cavity or a large area of decay on the tooth surface, especially if the abscess started from untreated decay that worked its way deep into the tooth. In some cases, a piece of the tooth has broken off, leaving a jagged edge with dark, soft material visible inside.
Gum Swelling and Redness
Beyond the gum boil itself, the gum tissue around an abscessed tooth often looks swollen and inflamed. The tissue may appear a deeper red than the surrounding healthy gum, and it can look glossy or stretched from the swelling underneath. In a periapical abscess, where the infection sits at the very tip of the tooth root, the swelling may not be immediately visible on the surface but can create a firm, tender area deep in the gum that you feel more than you see.
A periodontal abscess, which forms in the gum pocket alongside the tooth rather than at the root tip, tends to produce more visible gum swelling. The gum between teeth may look puffy and balloon-like, and pressing on it can release pus from the gum line. The tissue around it often looks dark red or purplish compared to the pale pink of healthy gums.
Facial and Jaw Swelling
When an abscess progresses, the infection can cause visible swelling beyond the mouth. Where the swelling shows up on your face depends on which tooth is infected. An abscessed upper tooth, particularly a molar, often causes swelling in the cheek or just below the eye on that side. Lower tooth infections tend to produce swelling along the jawline or under the chin. In either case, the swollen area usually looks puffy and feels warm and firm to the touch. The skin over it may appear slightly flushed.
You may also notice tender, swollen lumps under your jaw or along the side of your neck. These are lymph nodes responding to the infection. They typically feel like firm, marble-sized bumps that are sore when you press on them.
What a Severe Infection Looks Like
Most tooth abscesses stay localized, but in rare cases the infection can spread into the deeper tissues of the neck and throat. This condition, called Ludwig’s angina, produces dramatic visible changes: the front of the neck swells significantly, the floor of the mouth becomes firm and raised, and the tongue may push forward or protrude because there’s no room left beneath it. The skin over the neck can appear discolored, and the swelling tends to develop rapidly over hours rather than days.
This level of spread is a medical emergency because the swelling can block the airway. If you see fast-moving swelling in the neck, difficulty swallowing, or a tongue that seems pushed out of position, that situation requires immediate emergency care rather than a dental appointment.
How to Tell It Apart From Other Mouth Issues
Several other conditions can look similar to a tooth abscess at first glance. A canker sore is flat or slightly indented with a white center and red border, and it forms on soft tissue like the inner lip or cheek, not on the gum line. A mucocele (a blocked salivary gland) creates a clear, bluish, fluid-filled bubble, usually on the inner lip or floor of the mouth. A gum boil from an abscess, by contrast, is opaque, yellow to red, and sits right on the gum tissue near a specific tooth.
Gum disease can also cause red, swollen gums that bleed easily, but the swelling is usually widespread across multiple teeth rather than focused on one spot. An abscess produces a localized pocket of swelling tied to a single tooth, often with a visible bump or drainage point. If you’re seeing a concentrated area of swelling, discoloration, or a bump that keeps refilling with fluid near one particular tooth, that pattern points toward an abscess rather than general gum inflammation.