Background: Receiving local anaestethic injection is painful. A double-blinded randomised study with 32 healthy adult volunteers was performed, with the aim of investigating the effect of buffering lidocaine to reduce the pain during injection.
Methods: Each participant received two subcutaneous injections of 4.5 ml lidocaine 1% on the lower left and right quadrants of the abdomen. One solution was plain lidocaine (pH 6.55) and the other was lidocaine buffered with sodium bicarbonate in a ratio of 9:1 (pH 7.30). After each injection the participant marked the pain experienced during the injection on a visual analogue scale (VAS; 0 = best, 100 = worst), in addition to verbally stating which injection they found was the least painful.
Results: A total of 20 stated that they preferred the buffered solution, while eight said that they preferred the unbuffered solution (p < 0.002). The mean VAS pain-score was 15 (SD = 12) for the buffered injections and 20 (SD = 12) for the unbuffered injections (p < 0.017).
Conclusion: The conclusion is that the pain experienced during the injection of lidocaine can be significantly reduced by buffering the solution before injection.
Keywords: Lidocaine; bicarbonate; injection; pain.