The most telling sign of a tooth infection is a persistent, throbbing pain that doesn’t go away on its own, often accompanied by swelling in your gums or face, sensitivity to hot and cold, and sometimes a foul taste in your mouth. If you also have a fever, the infection may be spreading beyond the tooth itself. Here’s how to recognize what’s happening and what to do about it.
The Core Symptoms of a Tooth Infection
Tooth infections don’t always announce themselves with dramatic pain. Sometimes the first sign is a dull, constant ache in one area of your mouth that gradually intensifies over days. Other times, the pain is sharp and throbbing from the start, radiating into your jaw, ear, or even up to your temple on the same side. The pain often gets worse when you lie down, because blood flow to your head increases and puts more pressure on the infected area.
Beyond pain, watch for these signs:
- Sensitivity to temperature: A sharp zing when you drink something hot or cold that lingers for several seconds after the trigger is gone. Brief, fleeting sensitivity is common with worn enamel, but pain that hangs around points toward deeper trouble.
- Pain when biting or chewing: Pressure on the infected tooth sends a jolt because the tissues around the root are inflamed.
- Swelling in the gums: You may notice a red, puffy area near the base of a tooth, or a small bump on your gum that looks like a pimple. That bump is a drainage point for pus collecting inside the infection.
- Bad taste or odor: If that gum bump ruptures, you’ll get a sudden rush of salty, foul-tasting fluid in your mouth. The pain often temporarily improves when this happens because the pressure is relieved, but the infection is still there.
- Facial swelling: Swelling that extends from your gum into your cheek or jaw means the infection has moved beyond the tooth into surrounding tissue.
- Tender lymph nodes: Swollen, sore lumps under your jaw or along your neck are your immune system reacting to the spreading infection.
Not every toothache is an infection. A cracked tooth, a cavity that hasn’t yet reached the nerve, or even a sinus infection can cause similar pain in your upper back teeth. The combination of pain plus swelling, drainage, or fever is what separates a likely infection from other causes.
Two Types of Tooth Infections
Tooth infections fall into two main categories depending on where the infection starts. A periapical abscess forms inside the tooth, at the tip of the root. This usually happens when a deep cavity or crack allows bacteria to reach the inner pulp of the tooth, which is the soft tissue containing nerves and blood vessels. The pulp dies, bacteria multiply, and pus collects at the root tip. Pain from a periapical abscess tends to feel like it’s coming from deep inside the tooth itself.
A periodontal abscess forms in the gum tissue beside a tooth, typically in a pocket where the gum has pulled away from the tooth surface. This type is more common in people with gum disease. The swelling is usually more visible along the gum line, and you might feel the painful bump directly with your tongue or finger. Both types need professional treatment. They won’t resolve on their own.
Signs the Infection Is Spreading
A contained tooth infection is a dental problem. A spreading tooth infection is a medical emergency. The transition can happen quickly, sometimes within hours. Fever and a general feeling of being unwell (fatigue, body aches, chills) are the clearest signals that bacteria have moved beyond the tooth into your bloodstream or surrounding tissues.
Over 90% of cases of Ludwig’s angina, a dangerous soft-tissue infection of the floor of the mouth, start with an infected lower molar. Symptoms include rapid swelling under the jaw and tongue, difficulty swallowing, drooling, and trouble breathing. This condition can become life-threatening if the swelling closes off the airway.
Go to an emergency room if you have facial swelling extending into your neck, difficulty breathing or swallowing, a fever you can’t control, or swelling that’s visibly getting worse over the course of hours. These situations can’t wait for a dental appointment.
What Happens at the Dentist
Your dentist will start by asking about your pain: when it started, what makes it worse, whether it’s constant or comes and goes. Then they’ll examine the area visually, looking for swelling, discoloration, and any drainage. They’ll likely tap on the suspect tooth and its neighbors with a small instrument. A tooth with an infected root will feel distinctly more painful when tapped compared to healthy teeth around it. They may also have you bite down on something to see if pressure reproduces the pain.
An X-ray is the key diagnostic tool. Infections at the root tip show up as dark areas on the image because the bone around the root has been destroyed by the abscess. This confirms both the location and the extent of the infection. In some cases, a dentist will test the tooth’s response to cold to check whether the nerve inside is still alive or has died.
Current guidelines from the American Dental Association recommend treating tooth infections with dental procedures rather than antibiotics alone. That means removing the infected tissue through a root canal, draining the abscess, or extracting the tooth if it can’t be saved. Antibiotics are reserved for cases where the infection has progressed to systemic involvement, meaning you have a fever, feel generally ill, or the swelling is significant and spreading. An antibiotic without treating the source of the infection just delays the problem.
What You Can Do Before Your Appointment
If you’re waiting a day or two to see a dentist, a few things can help manage the discomfort. A warm saltwater rinse, made with one teaspoon of salt in eight ounces of warm water, can help draw out some fluid from the swollen tissue and keep the area cleaner. If your mouth is very tender, start with half a teaspoon of salt instead. You can rinse several times a day, especially after eating.
Over-the-counter pain relievers can take the edge off. Applying a cold pack to the outside of your cheek in 20-minute intervals can reduce swelling. Sleep with your head elevated on an extra pillow to limit blood pressure in the infected area. Avoid very hot or cold foods and drinks if temperature sensitivity is part of your symptoms, and try to chew on the opposite side of your mouth.
These measures manage symptoms. They don’t treat the infection. The bacteria inside the tooth or gum pocket are walled off from your bloodstream in a way that makes it impossible for your immune system to clear them without professional intervention. Even if the pain fades temporarily, particularly after a gum bump drains on its own, the infection will return and typically worsen.