When Does a Tooth Infection Become Dangerous? Signs and What to Do

Why no one can give you a timeline

You may read that a tooth infection turns deadly within a set number of days or weeks. None of the guidance or studies we checked gives a reliable time for an untreated tooth infection to become dangerous. How an infection behaves depends on where it is, how the body responds to it, and whether it is treated.

What the guidance does give is a set of warning signs. Scottish dental prescribing guidance (SDCEP) and the NHS describe what a spreading infection looks like and when it becomes an emergency. Those signs are listed below, and they are the reason not to wait and see.

Some people are more vulnerable if an infection does spread. SDCEP's list for sepsis includes people under 1 or over 75¹, people who are frail, pregnant or have a weakened immune system, and people who have recently had surgery or repeated courses of antibiotics. If you are in one of these groups, have a tooth infection seen sooner rather than later.

How a tooth infection can become serious

An abscess at the root of a tooth is a pocket of pus. The NHS says it will not go away on its own² and needs urgent treatment by a dentist. Left untreated, the infection can spread.

• Into the face, jaw and neck. Swelling can spread under the skin (cellulitis) and into the spaces of the neck. SDCEP tells dentists to send patients to hospital as an emergency for swelling of the floor of the mouth, difficulty breathing or swallowing³, a jaw that will hardly open, or rapidly spreading swelling. Swelling under the tongue and jaw can narrow the airway; one named form of this is Ludwig's angina.
• Into the sinus and around the eye. An infected upper back tooth can cause sinusitis. A review of reported cases found 110 cases with complications beyond the sinus, about 70 in 100 of them around the eye⁴, most often from infection at the root of an upper molar. These were collected case reports, so they cannot tell us how often this happens.
• Through the whole body (sepsis). Sepsis is when the body's response to an infection starts to damage its own organs. SDCEP describes sepsis from a dental infection as rare but potentially life-threatening¹.

How often does it become life-threatening?

The figures that exist are few, and easy to misread. A US study looked at 61,439 hospital stays between 2000 and 2008 in which the main diagnosis was an abscess at the root of a tooth. 66 of those patients died in hospital⁵. That is about 1 in 1,000 of those hospital stays, by our own calculation. Most of the admissions (89 in 100) were emergencies or urgent, and the average stay was about 3 days.

This figure is not your risk. It counts only people who were already ill enough to be admitted to hospital in the US, not everyone with a tooth infection, and the study summary does not say whether the abscess caused each death. No source we checked gives the share of tooth abscesses that become dangerous, so we do not give one. What the figures do show is that people admitted with a tooth abscess can die, which is why the warning signs below matter.

Warning signs: when to act now

Call 112 or go to the nearest emergency department, without waiting for a dental appointment, if you have a tooth infection and:

• you find it hard to breathe, speak or swallow
• your eye is swollen or painful, or your eyesight changes suddenly
• your neck is swollen
• there is a lot of swelling inside your mouth
• you find it hard to open your mouth
• swelling in your face or mouth is spreading quickly

These signs come from the NHS abscess² and toothache⁶ pages. Sepsis signs can be vague: SDCEP lists confusion, uncontrollable shivering (rigors), breathlessness, a fast heart rate, a very high or low temperature and mottled skin. If you have a dental infection and feel like this, get emergency help.

Ask for an urgent dental appointment, if none of the emergency signs above applies, when:

• you think you have an abscess
• your face or jaw is swollen
• you have toothache with a high temperature

The NHS lists these as reasons to see a dentist urgently rather than to call emergency services.

How the infection is treated

The infection is dealt with by treating the tooth. The dentist drains the pus under local anaesthetic and removes the cause, usually with root canal treatment or by taking the tooth out. SDCEP tells dentists to treat an abscess first with local measures³: drainage and, where possible, removing the cause.

Antibiotics have a place, but not instead of treatment. SDCEP says to consider them when there is cellulitis, spreading infection or systemic involvement⁷, or when local measures have not worked. If you are given antibiotics, the tooth still needs treatment. SDCEP advises a review after about 3 days; if you get worse before then, contact your dentist without waiting.

Until you are seen, ordinary painkillers such as ibuprofen or paracetamol can help if they are safe for you. Stay within the dose on the pack. Do not squeeze or prick a swelling yourself. Painkillers can make you feel better while the infection continues, so the warning signs above still apply.

Frequently asked questions