Tooth abscess: what it is, why it happens, and what to do

A tooth abscess is a painful swelling of the gum or the face caused by an infection in a tooth or in the gum.

It doesn’t heal on its own: even if the pain stops, the infection is still there until the dentist drains it and treats the cause, with a root canal or by removing the tooth. If your eye or neck swells up, or you find it hard to breathe, swallow or open your mouth, go to the emergency room.

“I think I have an abscess” is one of the things dentists hear every day. Here’s what it is exactly, how a spreading infection differs from an abscess, why it happens, when it’s serious, what you can do while you wait for your appointment, when antibiotics help, and how it’s treated at the clinic.

What a tooth abscess is

The medical dictionary of the Clínica Universidad de Navarra defines a phlegmon as an acute, diffuse inflammation, almost always caused by an infection, that spreads through the tissue without being enclosed in a cavity.

In Spanish, the word is “flemón”. The same dictionary explains that in everyday speech it has come to mean almost only the painful gum swelling caused by a tooth infection, and that the Real Academia Española records it that way. So if you’re in Barcelona and someone says “flemón”, they mean what English speakers usually call a tooth abscess.

An infection in the gum looks like a red, swollen area, sometimes with a bump, next to a tooth that hurts. As the infection progresses, the swelling can spread to the cheek, the lip or the jaw: that’s what people mean by a swollen face from a tooth infection.

Spreading infection or abscess: what’s the difference

In medical terms they aren’t the same thing, although people use the words interchangeably:

• Spreading infection (phlegmon). The infection spreads through the tissue with no wall to contain it. The area is swollen, hard and warm.
• Abscess. The body has managed to enclose the pus inside a capsule. That’s why it can be drained more precisely.

According to the same Clínica Universidad de Navarra, they’re stages of the same process: a spreading infection can turn into an abscess if your defenses wall it off, or it can spread further if the infection overwhelms them.

The NHS, the UK’s public health service, describes a dental abscess as a buildup of pus in the tooth or the gum caused by an infection, and says it needs urgent treatment from a dentist. When there’s pus in the gum, we’re already talking about an abscess.

What causes a tooth abscess

The NHS explains that a dental abscess forms when pus collects under a tooth or the gum because of an infection in the mouth. These are the causes it lists:

• Tooth decay. When it reaches the inside of the tooth, the infection can break out toward the gum. The Clínica Universidad de Navarra explains that this kind of swelling usually starts with an infection of the tooth’s nerve or of the gum that spreads to the surrounding tissue.
• Gum disease. The infection starts in the gum, around the tooth.
• A tooth that hasn’t come in properly, such as infected wisdom teeth, which stay partly erupted and trap debris under the gum.
• An injury to the tooth, the gum or the mouth.
• Radiation therapy or chemotherapy, which weaken the mouth’s defenses.

Symptoms: pus in the gum, pain and a swollen face

The symptoms of a dental abscess listed by the NHS are:

• intense pain in a tooth or the gum;
• redness inside the mouth or on the face or jaw;
• sensitivity to cold or heat in that area;
• a bad taste in your mouth;
• difficulty opening your mouth and chewing;
• a swollen face or jaw;
• swollen glands in your neck;
• a fever.

If you’re not sure whether it’s an abscess or another kind of gum or tooth pain, the article on solutions for gum pain gives you the clues to tell them apart.

Is a tooth abscess dangerous? When to go to the ER

A severe tooth infection can spread beyond the mouth. The Clínica Universidad de Navarra notes that if the infection overwhelms your defenses, it can go on to destroy tissue and cause a general infection. That’s why the NHS says to go to the hospital emergency room, without waiting for a dental appointment, if:

• you find it hard to breathe, speak or swallow;
• your eye is swollen or sore, or your vision suddenly gets worse;
• you have a lot of swelling inside your mouth;
• you find it hard to open your mouth.

Don’t drive yourself: ask someone to take you or call 112, the emergency number in Spain. Outside those cases, an abscess calls for an urgent appointment with the dentist, not for waiting until it goes away.

What to do while you wait for your appointment

These are the NHS recommendations for managing the pain until treatment:

• Take a painkiller such as ibuprofen or paracetamol (acetaminophen), never going over the dose on the leaflet. Children under 16 shouldn’t take aspirin.
• Eat soft foods: soup, scrambled eggs, mashed potatoes or yogurt.
• Brush with a soft toothbrush, including the area that hurts.
• Avoid very cold or very hot food and drinks.

What you shouldn’t do is try to drain an abscess at home. The NHS explains that it’s the dentist who drains the pus, with local anesthesia so that it doesn’t hurt. Pricking or squeezing the bump doesn’t get rid of the infection in the tooth.

Antibiotics for a tooth abscess and toothache: when they help

Many patients come in asking for an antibiotic for their toothache. The 2019 guideline from the American Dental Association (ADA), based on a systematic review, recommends against antibiotics in the majority of cases of dental pain or swelling, because their benefit is probably minimal and their harms can be large.

It reserves them for when the infection affects the whole body, with a fever or feeling generally unwell, or when the risk of it reaching that point is high. And in every case, it gives priority to treating the tooth as soon as possible.

In other words, an antibiotic can slow down an infection that’s spreading, but it doesn’t fix the tooth that’s causing it. That’s why, unless the tooth is treated, the abscess won’t clear up.

How a tooth abscess is treated at the clinic

The NHS describes the treatment in two parts: the dentist drains the pus and then treats the tooth that caused the infection. Depending on the condition of the tooth:

• Root canal. The inside of the tooth is cleaned and sealed so the tooth can be kept. At the clinic, endodontics starts at €175.
• Extraction. If the tooth can no longer be saved, it’s removed. A simple extraction costs €40, and a wisdom tooth extraction costs €60.
• Gum treatment. If the cause is gum disease, the infected pocket and the root are cleaned.

Everything is done under local anesthesia. Afterward, you may be told to take painkillers for a few days and, sometimes, antibiotics. The first visit and the quote are free.

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