Antibiotics for a Tooth Infection: When They Help and When They Don't

Why antibiotics alone do not fix the tooth

The causes the NHS lists for a dental abscess include tooth decay, gum disease and an injury to the tooth. When decay reaches the nerve inside a tooth, the nerve can die and infection can collect as pus around the tip of the root. That collection is an abscess. The NHS is plain about it: a dental abscess will not go away on its own¹ and needs urgent treatment by a dentist.

When an abscess comes from an infected nerve, the source of the infection is inside the tooth, where tablets cannot clean it. Scottish dental prescribing guidance (SDCEP) explains that an abscess confined to the tissue around the root is mostly isolated from the circulation, so very little antibiotic gets into it². That is why it tells dentists to treat an abscess first with local measures: draining the pus and, where possible, removing the cause.

The trials point the same way. A 2024 Cochrane review found 3 small trials with 134 adults in whom an antibiotic or a dummy tablet was added to root canal treatment. One tested a single dose before treatment in people without an abscess; two tested a 7-day course. None showed a clear difference in pain or swelling³, and the certainty of the evidence was low to very low. No trial compared antibiotics with a dummy tablet without any dental treatment, so there is no evidence that tablets alone are enough.

When dentists do use antibiotics

Both the Scottish guidance and the American Dental Association (ADA) keep antibiotics for particular situations. SDCEP's general rule is that antibiotics must only be prescribed when clinically indicated⁴, with local treatment first unless the infection is spreading or affects the whole body. For a dental abscess it names three situations:

• The infection is spreading: swelling that is growing, cellulitis (a spreading infection under the skin) or swollen glands in the neck.
• It is making you unwell: a fever or feeling generally unwell (malaise).
• The pus cannot be drained straight away with local treatment.

The ADA's 2019 guideline for adults with a healthy immune system reaches a similar position. When a dentist cannot start treatment straight away and there is a local abscess, the panel suggests an antibiotic together with an urgent referral⁵ for the treatment itself. This is a conditional suggestion based on very low certainty evidence. When the infection has spread and you are unwell, the guideline calls for urgent treatment together with antibiotics.

The two guidelines broadly agree: no antibiotics for a local abscess that can be drained and treated, and antibiotics when drainage is not possible, the infection is spreading or the whole body is involved. If your immune system is weakened by an illness or a medicine, tell your dentist, because the decision may be different.

When antibiotics are not recommended

For toothache from an inflamed nerve. Pulpitis is inflammation of the pulp, the soft tissue inside the tooth that holds its nerve. SDCEP counts it among inflammatory conditions and says antibiotics should not be used to manage the pain⁴ of such inflammatory conditions. The ADA panel recommends against them for this pain, a strong recommendation based on low certainty evidence. A Cochrane review found only one small trial of 40 people⁶ and called the evidence insufficient to say whether antibiotics reduce the pain or not. So they are not recommended, and there is no good evidence that they help.

On top of treatment for a local abscess. When the dentist can drain the abscess and treat the tooth, the ADA recommends against adding an antibiotic. The panel weighed benefits of little to no difference against a potentially large increase in harm⁵, such as side effects. That is a strong recommendation, although it rests on very low certainty evidence.

An antibiotic can make a swelling settle for a while. If the cause stays in the tooth, the infection can return.

For the pain itself while you wait, SDCEP notes that most dental pain can be relieved by anti-inflammatory painkillers⁷ such as ibuprofen, if they are safe for you. Painkillers are only a temporary measure; follow the pack, and ask a pharmacist if you are not sure.

If you are given antibiotics

• Still have the tooth treated. The antibiotic buys time; it does not replace drainage, root canal treatment or removal of the tooth. Keep the appointment for the treatment itself.
• Expect a short course and a review. SDCEP says a course for a dental abscess is usually 3 to 5 days², with a review ideally at about day 3.
• Do not wait for the review if you get worse. The ADA guideline tells dentists to ask patients to call if their condition deteriorates. If you feel worse on the medicine, or think you are reacting to it, contact your dentist or pharmacist straight away. Swelling that makes it hard to breathe or swallow is an emergency (see below).
• Stop when your dentist tells you to. The guidelines used here do not say that every course must be finished whatever happens. SDCEP advises dentists to tell the patient to stop once the general signs and symptoms have gone. The ADA tells dentists to have patients stop 24 hours after their symptoms resolve⁵. In both, the dentist decides and gives you the instruction; do not change the dose or stop early on your own.
• Follow the instructions on the pack and from your pharmacist. We do not give doses here: the right medicine and dose depend on you and are for the prescriber to set.
• Mention allergies and other medicines before anything is prescribed.

The root canal treatment page explains how a tooth with an infected nerve is treated: root canal treatment.

When to see a dentist, and when it is an emergency

See a dentist urgently if you think you have an abscess. The same applies if your face or jaw is swollen, or if toothache comes with a high temperature. These are reasons for an urgent dental appointment⁸, not a routine one.

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

• swelling that makes it hard to breathe, speak or swallow
• a swollen or painful eye, sudden problems with your eyesight, or swelling in your neck
• a lot of swelling inside your mouth
• difficulty opening your mouth

These signs are taken from the NHS abscess and toothache pages. Rarely, a dental infection leads to sepsis, when the body's response to an infection starts to damage its own organs. SDCEP calls this rare but potentially life-threatening⁹. Its signs can be vague: confusion, uncontrollable shivering (rigors), breathlessness, a fast heartbeat or mottled skin. If you have a dental infection and feel like this, get emergency help rather than waiting for the dentist.

Frequently asked questions