EasyCare patient guide
Dental local anaesthetic: what to expect and how long numbness lasts
Local anaesthetic numbs a small area for dental treatment while you remain awake. You may notice the injection and pressure during treatment, but tell your dentist if you feel pain so they can pause and check the numbness.
This guide answers questions about the injection, numbness, side effects and what to do before and after your appointment.
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Treatment is planned around your health history and the procedure.
What does dental local anaesthetic do?
The medicine temporarily blocks pain signals from a tooth and nearby tissues. It is commonly used for fillings, tooth removal and root canal treatment. You remain conscious, can communicate and may still feel movement, pressure or vibration.
Your dentist chooses an injection site and dose for the treatment. A surface numbing gel may be used first. They then allow time for the medicine to work and check the area before starting. Extra anaesthetic or a different technique may be needed if the first injection does not numb the tooth adequately.
Tell us if you feel pain
Raise a hand or speak up. The dentist can stop, reassess and adjust the approach. You should not have to silently tolerate sharp pain.
If the thought of an injection is the main concern, our dental anxiety guide covers ways to discuss fears and plan a visit. This article focuses on the anaesthetic itself.
Before the injection: what should you mention?
Health and medicines
Tell your dentist about allergies or prior reactions, your medical conditions, medicines, pregnancy or breastfeeding, and any recent changes in health. Local anaesthetic preparations may include a medicine that narrows blood vessels, often called adrenaline. The safest option and dose depend on your circumstances.
Previous difficulty getting numb
Let the dentist know if previous dental injections have not worked well, which tooth was treated and what you felt. Inflamed tissue, tooth anatomy and the injection technique can affect the result. This helps the team plan and test numbness carefully.
How long will my mouth stay numb?
The time varies with the medicine, dose, injection site and your response. A tooth, tongue, lip or cheek can remain numb for several hours even after treatment ends. Your dentist can tell you what is expected for your appointment.
- Avoid biting or chewing the numb lip, cheek or tongue. Take care with hot drinks until normal feeling returns.
- Follow the aftercare instructions for your actual treatment, especially after an extraction or procedure involving a wound.
- If numbness persists much longer than your dentist advised, or you develop new concerning symptoms, contact the practice for advice.
Local anaesthetic alone usually does not make you drowsy, but sedation and other medicines can affect driving. Follow the instructions you receive for your specific appointment.
Possible side effects and when to get help
Effects that may pass
Temporary tenderness or bruising where the injection was given, a brief tingling sensation, or an accidental bite while numb can occur. Some people notice a short-lived racing heartbeat or shakiness after an injection containing adrenaline; tell the dentist at once if you feel unwell.
Symptoms needing prompt attention
Tell your dentist immediately about trouble breathing, swelling of the lips or throat, faintness, an unusual rash or other sudden severe symptoms. For a medical emergency, call 000. If symptoms arise after you leave, contact the practice or seek urgent care.
Your clinician can explain benefits and risks for the anaesthetic and procedure you are having. This general guide cannot determine the cause of an individual reaction.
Questions patients ask about dental anaesthetic
Will the injection hurt?
You may feel a small pinch or pressure. A surface gel and slow injection may help. Tell your dentist if you are worried or want a pause.
Why is my lip numb when only one tooth is being treated?
The injection may numb a nerve that also supplies part of your lip, cheek or tongue. This usually wears off as the anaesthetic wears off.
What if my tooth is still painful after the injection?
Tell the dentist before or during treatment. They can test the tooth and consider more anaesthetic or another approach.
Is local anaesthetic safe in pregnancy?
Dental care and local anaesthetic can often be planned during pregnancy, but tell the dentist you are pregnant or might be pregnant so the medicine and timing can be chosen for you. For broader questions about oral changes, treatment timing and X-rays, read our dental care during pregnancy guide.
Can I drive after a local anaesthetic injection?
Local anaesthetic alone generally does not impair alertness. Driving advice changes if you also have sedation, other medicines or a procedure that affects you. Follow your clinician’s specific instructions.
Explore the treatment you are considering
For the procedure itself, see our dental fillings, root canal treatment and tooth removal pages. The anaesthetic plan is discussed in the context of your treatment and health history.
Questions before your appointment?
Tell us about any prior reaction, difficulty getting numb or concern about injections. We can discuss what is appropriate for your treatment before starting.
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