Local anaesthetic injections are a standard part of many dental procedures. Understanding what to expect can help you feel more prepared for your appointment. This page explains how dental injections work, what you may experience during and after the injection, and the potential side effects.
Your dentist starts by drying the area of your mouth with air or cotton, then applies a topical anaesthetic (numbing gel) onto the gum to reduce sensation before the injection. When the needle is inserted, the anaesthetic is delivered slowly and in small steps. The dentist adds extra drops of anaesthetic ahead of the direction the injection is moving, injecting into tissue that is already numbing, which is designed to reduce discomfort.
There are two main types of anaesthetic injections. A block injection numbs a larger area of the mouth and is usually used for the lower teeth. An infiltration injection numbs a smaller, more localised area and is typically used for the upper teeth. The anaesthetic takes 3 to 5 minutes to reach full effect and lasts up to several hours after the procedure.
Most patients experience some sensation during the injection. This commonly includes a stinging or pressure feeling as the solution enters the tissue. The level of discomfort varies between patients and depends on the injection site, the type of injection, and individual sensitivity. Some patients find certain injection sites — particularly block injections in the lower jaw — more uncomfortable than others.
Your dentist uses techniques to reduce discomfort, including topical anaesthetic gel applied before the injection and a slow injection rate. However, some discomfort during the injection is normal and expected.
The most commonly used local anaesthetic in dentistry is Lidocaine. Like all medications, it can cause side effects.
Common effects include numbness extending beyond the treatment area (lips, tongue, cheeks, or nose), which typically wears off within 45 minutes to a few hours; a tingling or "funny" feeling in the numbed areas; bruising or soreness at the injection site; and temporary difficulty eating or speaking while numb.
Less common side effects of Lidocaine include apprehension, dizziness, drowsiness, lightheadedness, nervousness, and ringing in the ears. Allergic reactions to local anaesthetic are rare but possible.
Always inform your dentist of any medications you are currently taking, any allergies you have or have had in the past, and any previous adverse reactions to anaesthesia.
Because the numbed area cannot feel pain, you can accidentally bite your lips, cheeks, or tongue without realising. This is a particular risk for children. Avoid eating or chewing until the numbness wears off. If you need pain medication after your procedure, take it shortly after treatment so it takes effect before the anaesthetic wears off — pain relief typically takes about 30 minutes to work.
Several types of anaesthesia are used in dentistry depending on the procedure: local anaesthetic (injection to numb a specific area), nitrous oxide (inhaled sedation for relaxation), conscious sedation (IV sedation for deeper relaxation), and general anaesthesia (full unconsciousness, used in hospital settings for complex procedures). Your dentist will recommend the appropriate type based on your procedure and medical history.
For full information about treatment risks, please visit our treatment risks page: https://www.gorgeoussmiles.com.au/treatment-risks/
If you have questions about dental anaesthesia or would like to discuss your concerns before a procedure, call Gorgeous Smiles on (03) 9042 0483 or book an appointment online.
Gorgeous Smiles Melbourne CBD | 121 Exhibition St | Book online or call (03) 9042 0483
Author: Dr Minoo Ghamari, Gorgeous Smiles Dental Principal Dentist
The content on this blog is not intended to substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of a qualified dentist with questions you may have regarding medical conditions.
All dental treatment carries risks. The treatments described on this site may not be appropriate for your oral health. A full consultation with an AHPRA-registered dental professional is required before confirming suitability for any procedure. Individual results vary. For information about treatment risks, please visit our treatment risks page.