A dental abscess is a collection of pus caused by a bacterial infection in a tooth or the surrounding tissues. It can cause pain, swelling and sensitivity. A suspected tooth infection needs prompt dental assessment because it can spread if left untreated.
When antibiotics are used
Not every tooth infection needs antibiotics. Your dentist usually treats the source first, using drainage, root canal treatment or extraction where appropriate.
Antibiotics may be needed alongside dental treatment if the infection is spreading, causes fever or other signs of illness, or local treatment is not effective. Your dentist will also consider your immune system, medical history and medicines.
Antibiotics are not routinely needed before a root canal or extraction. They do not replace treatment of the infected tooth.
Treating the source of the infection
The appropriate treatment depends on the tooth and the location of the infection:
- Drainage: your dentist releases pus from the abscess. Further treatment may still be needed to remove the cause.
- Root canal treatment: removes infected tissue from inside the tooth, then cleans and seals the root canals.
- Tooth extraction: may be needed if the tooth cannot be saved.
Even if antibiotics ease the pain, keep the dental appointment to address the underlying problem.
How long do antibiotics take to work?
The response varies with the infection, the antibiotic and whether the source has been treated. Symptoms may start to improve over the first few days, but improvement does not mean the tooth has been treated.
Take antibiotics exactly as prescribed, including the dose and duration. Follow any review instructions and do not change or stop treatment without speaking to the prescriber. Never share antibiotics or use leftover tablets.
Contact your dentist promptly if symptoms worsen or are not improving as expected. Do not wait until the course ends if swelling or illness is increasing.
Side effects and warning signs
Possible side effects include nausea, diarrhoea, rashes and allergic reactions. Tell your dentist about allergies, other medicines and relevant medical conditions before starting treatment. Your pharmacist can explain drug-specific precautions and interactions.
Call 112 or 999 for breathing or swallowing difficulty, severe swelling of the mouth or neck, or signs of a serious allergic reaction. Seek urgent help for swelling around the eye or rapidly worsening symptoms.
For severe or persistent diarrhoea, a new rash or other concerning side effects, contact the prescriber or pharmacist promptly.
Frequently asked questions
Answers to common questions about antibiotics and dental infections.
Do I always need antibiotics for a tooth infection?
No. Many infections are treated by addressing the source through drainage, root canal treatment or extraction. Antibiotics may be added for spreading infection, systemic illness or other clinical reasons.
How long do antibiotics take to work on a tooth infection?
It varies. Symptoms may begin to ease over the first few days, but antibiotics do not replace treatment of the tooth. Contact your dentist if you are getting worse or are not improving as expected.
Why must I follow the prescribed antibiotic course?
The dose and duration are chosen for your infection and circumstances. Take the medicine exactly as prescribed and attend any review. Speak to the prescriber before changing treatment, and get advice promptly if side effects occur.
What happens if a tooth infection is left untreated?
An infection can spread beyond the tooth into nearby tissues and can become serious. Get prompt dental care. Breathing or swallowing problems, severe mouth or neck swelling, or swelling around the eye require emergency help.
Can I take painkillers while I wait for my appointment?
Suitable over-the-counter pain relief may help temporarily. Follow the packet instructions, avoid exceeding the stated dose and ask a pharmacist if you are unsure what is safe with your health conditions or medicines. Painkillers do not treat the infection.
What are the side effects of dental antibiotics?
Side effects depend on the medicine and may include nausea, diarrhoea, rash or an allergic reaction. Discuss your medical history and medicines with your dentist or pharmacist. Breathing difficulty or swelling of the lips, tongue or throat needs emergency help.
How common are cavities and tooth infections?
Tooth decay is common, but not every cavity becomes an abscess. Treating decay early and maintaining good oral hygiene can reduce the risk of infection. Regular dental check-ups help identify problems before they become more serious.
Further reading: Dental abscess (HSE).
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