Tooth abscess: how to recognise it, and why it needs prompt care.

An abscess is a collection of pus from a bacterial infection. A periapical abscess forms at the tip of the root, usually when decay or a crack lets bacteria reach and kill the nerve; a periodontal abscess forms in the gum alongside advanced gum disease. The body walls the infection off, which builds pressure — hence the pain. Crucially, an abscess will not resolve without treatment; even if the pain eases (because the nerve has died), the infection continues underneath.

The usual route is bacteria reaching the inside of the tooth through deep, untreated decay, a crack or chip, or a failed filling — they infect the pulp, which dies, and the infection collects at the root. A periodontal abscess instead comes from bacteria trapped in a deep gum pocket in established gum disease. Either way the trigger is bacteria getting somewhere they shouldn't and the body being unable to drain the resulting infection on its own.

Common signs are a severe, throbbing toothache that may spread to the jaw, ear or neck, pain on biting, swelling of the gum, face or jaw, tenderness, sensitivity to hot and cold, a bad taste or salty fluid if it bursts, and sometimes a fever or generally feeling unwell. A pimple-like bump on the gum that weeps is a draining abscess. Pain that suddenly stops is not reassurance — it can mean the nerve has died while the infection persists.

Get urgent care — same day — if there is swelling spreading to the eye or neck, a high fever, or you feel very unwell. Difficulty breathing or swallowing is a medical emergency: go to A&E, as a spreading dental infection can compromise the airway. Even without those red flags, an abscess needs prompt dental treatment rather than days of painkillers — masking it while the infection grows is how a manageable problem turns dangerous.

Treatment drains the infection and removes its source. For a tooth abscess that usually means a root canal to clean out the infected pulp and save the tooth, or extraction if it cannot be saved; the abscess is drained either way. A periodontal abscess is drained and the gum pocket cleaned. Antibiotics may be added if the infection is spreading or you are unwell, but they do not fix the cause on their own — the tooth or gum still needs treating. Relief is usually rapid once it's drained.