Warming and Buffering Lidocaine Reduces Injection Pain

Buffering lidocaine reduces the pain of injecting the local anesthetic. Warming lidocaine to about 40°C has also been shown to reduce the pain of injection. This randomized, controlled study compared pain of injection with four different solutions of lidocaine: room-temperature and unbuffered; warm; buffered; and warm and buffered.

Thirty-two subjects each received an injection with each of the four solutions. After injection, the subjects compared on a visual analog scale the pain of the solution infiltrating and the pain of the needle entering the skin. The solutions were injected with a 25-gauge needle on a tuberculin syringe. The warm solutions were prepared by placing 30 cc vials of plain 1% lidocaine in an IV solution warmer (40°C). Th…