A tooth infection typically announces itself with a persistent, throbbing pain that doesn’t go away on its own and often gets worse over hours or days. Unlike the brief zing of sensitivity to hot or cold food, an infected tooth produces pain that lingers, radiates into your jaw or ear, and may wake you up at night. If you’re wondering whether what you’re feeling is an infection, there are several reliable signs to look for.
The Pain Feels Different From Sensitivity
Normal tooth sensitivity is quick and predictable. You bite into ice cream, feel a sharp flash, and it fades within seconds. Infection pain behaves differently. It throbs on its own without a trigger, intensifies when you bite down or press on the tooth, and can spread along your jawline, up toward your ear, or down into your neck. The pain often builds gradually over days rather than appearing suddenly.
One useful distinction: if the pain only affects your upper back teeth and comes with a stuffy nose, headache, or gets worse when you bend forward, a sinus infection may be the real cause. The roots of your upper molars sit very close to your sinus cavities, so inflamed sinuses can mimic a toothache. Pain from a dental infection is more localized to a specific tooth, responds to pressure on that tooth, and doesn’t fluctuate with your nasal congestion.
Visible Changes in Your Gums
Look in a mirror and check the gum tissue around the tooth that hurts. Redness and swelling along the gum line are common early signs. As the infection progresses, you may notice the gum pulling away from the tooth or a pus-filled bump forming on the gum near the root. This bump, sometimes called a gum boil, looks like a small pimple and may bleed or ooze when pressed. It forms because the infection creates a pocket of pus that needs somewhere to drain.
The affected tooth itself might feel slightly loose, or you might notice a strange sensation that the tooth is sitting higher than the teeth around it. That “elevated” feeling happens because pressure from the infection pushes the tooth upward in its socket.
A Bad Taste or Persistent Bad Breath
If you notice a bitter, salty, or foul taste in your mouth that won’t go away with brushing, that’s a strong indicator. The bacteria causing the infection produce sulfur compounds that smell and taste terrible. When an abscess drains pus into your mouth, the taste becomes even more distinct. Some people describe it as metallic or rotten.
Persistent bad breath that doesn’t improve with normal oral hygiene is another hallmark. The odor comes directly from the bacterial overgrowth and pus accumulation at the infection site. If someone close to you mentions your breath or you can taste something off throughout the day, the infection is likely draining intermittently.
Two Types of Tooth Infections
Not all tooth infections start the same way, and knowing the difference helps you describe what’s happening to your dentist.
A periapical abscess starts at the tip of the tooth’s root. This is the classic “infected tooth” most people picture. It usually develops after untreated decay, a crack, or trauma damages the nerve inside the tooth. The nerve tissue dies, bacteria multiply in the dead space, and infection builds at the root tip. Pain tends to be deep and constant, and the tooth often stops responding normally to hot or cold because the nerve is no longer alive.
A periodontal abscess starts in the gum tissue surrounding the tooth, usually in someone who already has gum disease. Deep pockets between the gum and tooth trap bacteria, and the pocket becomes infected. The pain is more focused on the gum itself, the tooth may feel loose, and pressing on the gum near the tooth can produce visible pus. The tooth’s nerve is often still healthy, so it reacts normally to temperature changes.
Signs the Infection Is Spreading
A tooth infection that stays contained to the tooth and surrounding gum is painful but manageable with dental treatment. The real danger comes when the infection moves beyond that area. Watch for these warning signs:
- Fever: Your body is now fighting the infection systemically, not just locally.
- Facial swelling: Swelling in your cheek, under your jaw, or around your eye means the infection has spread into deeper tissue.
- Swollen lymph nodes: Tender lumps under your jaw or along your neck indicate your immune system is actively responding to spreading bacteria.
- Fatigue and feeling generally unwell: A sense of being sick that goes beyond just mouth pain suggests the infection is affecting your whole body.
Difficulty breathing or swallowing is the most serious red flag. This can mean the infection has spread into your throat or neck, and it requires emergency room care, not a dental office visit. The same applies if you have a high fever with facial swelling and can’t reach a dentist. These situations can become life-threatening.
What Happens at the Dentist
Your dentist will tap on the suspect tooth and the teeth around it to check for pain on percussion. A healthy tooth handles a light tap without issue; an infected one will send a jolt of pain. They’ll also apply cold or heat to the tooth to see whether the nerve responds. A tooth with a dead nerve from a periapical infection often feels nothing at all during temperature tests, which itself is a diagnostic clue.
An X-ray is typically the most definitive step. Infection at the root tip shows up as a dark shadow around the end of the root, where the bone has been destroyed by the abscess. For a periodontal abscess, the X-ray reveals bone loss along the side of the root and deeper-than-normal gum pockets, usually greater than 6 millimeters.
In rare cases where test results are inconclusive, a dentist may use an electric pulp tester, a small device placed against the tooth that sends a mild electrical signal. If the nerve is alive, you’ll feel a tingling sensation. No response suggests the nerve has died and infection is likely present.
What You Can Expect From Treatment
Treatment depends on which type of infection you have. A periapical abscess usually requires a root canal, where the dead nerve tissue and infected material inside the tooth are cleaned out, or an extraction if the tooth is too damaged to save. A periodontal abscess requires draining the pus and deep cleaning of the infected gum pocket. Antibiotics are sometimes prescribed alongside either procedure, especially if the infection has started to spread.
The key thing to understand is that a tooth infection does not resolve on its own. The pain might temporarily decrease if the abscess finds a way to drain, which can feel like improvement. But the underlying infection remains and will return, often worse. Even a small gum boil that drains and seems to disappear is a sign of an active infection that has simply found an outlet. The source still needs to be treated.