Does root canal treatment hurt? Pain before, during and after treatment, and how long it normally lasts

Does a root canal hurt more than an ordinary filling?

Root canal treatment usually hurts no more than having a filling, because the tooth and surrounding area are anaesthetised. The American Association of Endodontists (AAE) says most patients compare it to ordinary treatment for a cavity, feeling at most pressure or the movement of instruments.

The painful reputation of root canal treatment mainly comes from the pain patients bring with them. According to the AAE, pain associated with root canal treatment is usually caused by infection in the tooth, and the procedure is intended to relieve it.

The figures support this. A review of 72 studies found that an average of 81% of patients had pain before treatment, 40% a day afterwards and 11% after a week; pain intensity on a scale of 0 to 100 fell from 54 before treatment to 24 after a day and 5 after a week (Pak and White, 2011).

Why does the tooth usually hurt most before root canal treatment?

A tooth hurts before root canal treatment because its pulp is inflamed or infection has already spread to the tissues around the root. Pulpitis typically causes spontaneous pain, pain at night and lingering pain after cold, while inflammation around the root causes pain on biting; the article on pulpitis explains the differences.

Severe pain before treatment also predicts a more difficult first few days afterwards. In a meta-analysis of 15 studies covering 24 320 cases, spontaneous pain before treatment increased the risk of a postoperative flare-up 5.83-fold, and pain on tapping the tooth increased it 3.45-fold (Ohshima et al., 2026).

Pain suddenly disappearing does not mean the tooth has healed. The AAE describes a tooth that had hurt with cold and sweet foods for months; when the symptoms stopped, examination showed that the pulp had died.

What do you feel during root canal treatment?

During root canal treatment, with effective anaesthesia, you usually feel pressure, vibration and instruments moving rather than pain. The NHS, the UK's public health service, says an appointment usually lasts 1 to 2 hours, sometimes longer, so your jaw may tire from keeping your mouth open.

A numb lip does not always mean that the pulp is already anaesthetised. AAE teaching materials from 2009 explain that asking whether the lip is numb does not confirm pulpal anaesthesia, and in a painful vital tooth even no response to testing does not provide certainty; additional anaesthesia is indicated if pain occurs once treatment starts.

Agree a signal with your dentist, such as raising your hand, and indicate immediately if anything hurts. The same AAE materials say people who have previously had difficulty with anaesthesia are more likely to experience it again, so mention this before treatment.

Why is anaesthesia less effective with pulpitis, and what can the dentist do?

Anaesthesia is less effective with acute pulpitis, often called a hot tooth in dental practice, because inflammation changes how nerves work. The 2009 AAE materials list lower pH in inflamed tissues, a lower excitation threshold in nerves emerging from inflamed tissue and more sodium channels resistant to local anaesthetics; anxiety further lowers the pain threshold.

Lower molars with symptomatic irreversible pulpitis can be particularly difficult to anaesthetise. A 2025 meta-analysis of 28 studies found that a supplementary injection after an unsuccessful nerve block roughly doubled the anaesthetic success rate compared with a nerve block alone (RR 2.02; Rujirawan et al., 2025).

Supplementary anaesthesia is routine in root canal treatment: in the review of 72 studies, an average of 60% of patients needed it (Pak and White, 2011). Dentists have several options, and a separate article on dental anaesthesia explains the different types.

• Supplementary anaesthesia using another technique, such as intraosseous or periodontal ligament injection, which the AAE recommends when a nerve block is insufficient.
• Emergency treatment: opening the tooth and removing inflamed pulp from the chamber, then completing root canal treatment at another appointment.
• A medicated dressing in the canals and a tight seal over the tooth until the next appointment.
• Treatment under general anaesthesia after a joint dental and anaesthesiology assessment, when inflammation is too acute for local anaesthesia to work.

How many days does a tooth hurt after root canal treatment?

A tooth usually hurts for a few days to about a week after root canal treatment, with pain easing quickly. The review of 72 studies found pain in 40% of patients after 24 hours and 11% after 7 days, while average intensity fell from 24 to 5 on a hundred-point scale during that time (Pak and White, 2011).

The AAE describes tenderness around the tooth for a few days as normal, as well as mild jaw soreness from keeping the mouth open for a long time. The NHS adds that the area around the tooth may be swollen and sore but should improve within about two weeks.

The treatment approach also affects pain. A 2022 Cochrane review reports that pain within a week was more common after single-visit than multiple-visit treatment (RR 1.55, moderate-certainty evidence), especially in teeth with vital pulp, with similar use of painkillers.

The table outlines the usual course of the first few days and signs that mean you should contact the surgery. It is a simplified guide, not a self-diagnosis tool.

What is a root canal flare-up, and how often does it happen?

A root canal flare-up is severe pain or swelling after treatment that requires an unscheduled visit; this is the definition used in a 2026 meta-analysis. In 15 studies covering 24 320 cases, severe flare-ups occurred in 2.83% (Ohshima et al., 2026).

Risk was higher in women, lower teeth, teeth with dead pulp, a lesion at the root tip, spontaneous pain or pain on tapping before treatment, and with multiple-visit treatment and retreatment. Age, tooth type, number of canals and preparation technique had no clear association with flare-ups, and the authors rated the certainty of evidence as low.

The 2022 Cochrane review found no difference in the frequency of swelling and flare-ups between single-visit and multiple-visit treatment, with very low-certainty evidence. A flare-up needs assessment at the surgery; the dentist decides on further management and any medication after examining you.

When should you call about pain after root canal treatment?

Pain after root canal treatment warrants contact with the surgery if it increases instead of easing, remains severe for more than a few days or comes with swelling. The AAE lists signs that mean you should contact your treating dentist immediately.

A root filled tooth that begins to hurt after months or years without symptoms is different from pain in the first few days. It may indicate persistent or recurrent infection; the article on root canal retreatment explains the treatment options.

• Severe pain or pressure lasting more than a few days.
• Visible swelling inside the mouth or on the face.
• An allergic reaction to medication: rash, hives or itching.
• A bite that feels uneven after treatment.
• Loss of a temporary filling or crown; wearing away of a thin layer is normal.
• Return of the symptoms present before treatment.
• Swelling spreading to the face or neck with fever, or difficulty breathing or swallowing: hospital emergency department (SOR) or 112.

How it works at DentalBlue

At DentalBlue in Białystok, the clinic's price list item “Znieczulenie w endodoncji” (anaesthesia for endodontic treatment) costs 20 zł. Patients with pain can attend a “Wizytę z bólem” (pain appointment, 340 zł), which includes a panoramic X-ray, consultation, examination and pain relief. The clinic provides inhalation sedation with nitrous oxide (“Podtlenek azotu”, nitrous oxide, 170 zł). Treatment under general anaesthesia is available, including for patients whose inflammation is too acute for local anaesthesia to work; it starts with a joint dental and anaesthesiology consultation. The dentist determines the final scope and cost, and prices may change.