Lidocaine Injection

Indications

Lidocaine is a local anaesthetic, a medicine that numbs a part of the body. It is used as an injection to numb the area for dental work, stitching, minor surgery and other procedures; as a gel, spray, cream or ointment to numb the skin, mouth, throat or urethra before procedures and to ease pain from minor burns, sores or haemorrhoids; and in hospital, by injection into a vein, to treat certain dangerous heart rhythm problems.

How It Works

Lidocaine blocks sodium channels in nerve cells, so pain signals cannot travel along the nerve and the area goes numb. In the heart, the same action calms some abnormal rhythms.

Dosage and Administration

• Injections (local anaesthesia or heart rhythm): given only by a doctor, dentist or nurse, as prescribed. The dose depends on the procedure and body weight.
• Gel, cream, ointment or spray: apply a thin layer to the affected area as directed on the pack or by the doctor, usually up to 3 or 4 times a day. Do not use more than the pack allows.

After using it in the mouth or throat, do not eat or drink for about 1 hour, until the numbness wears off, to avoid choking or biting the tongue.

Interactions

Beta blockers such as Propranolol, and Cimetidine, can raise lidocaine levels. Using it with other heart rhythm medicines such as Amiodarone, or with other local anaesthetics, increases the risk of side effects on the heart and nervous system. Tell the doctor or dentist about all medicines you take.

Contraindications

• Allergy to lidocaine or other amide-type local anaesthetics.
• Injection into a vein: certain heart block conditions or severe slow heart rate, unless a pacemaker is in place.
• Porphyria.

Side Effects

On the skin or mouth: mild burning, redness or temporary loss of taste. After injection: soreness or bruising at the site.

Get urgent medical help if you notice numbness or tingling around the mouth, a metallic taste, ringing in the ears, dizziness, blurred vision, confusion, shaking or fits, a very slow or irregular heartbeat, or swelling of the face, lips or throat with difficulty breathing.

Pregnancy and Lactation

Lidocaine is widely used for local anaesthesia in pregnancy, including in dental work and childbirth, and is considered acceptable when a doctor or dentist uses it. Only small amounts pass into breast milk, and breastfeeding can usually continue.

Precautions and Warnings

Do not apply to large areas, broken skin or under tight dressings unless a doctor advises, as more can be absorbed. Do not use numbing gels on babies or young children for teething pain. Take extra care in liver disease, heart failure, epilepsy and in older people. Keep it away from the eyes.

Overdose

Too much can cause numb lips, dizziness, ringing ears, drowsiness, fits, slow heartbeat and breathing problems. This is an emergency; get medical help immediately.

Therapeutic Class

Local anaesthetic (amide type); class Ib antiarrhythmic.

Storage

Store below 30°C in a dry place, away from light and out of the reach of children. Do not freeze.