Preventive Effects of Lidocaine, Fentanyl, Acetaminophen, and TENS on Propofol-Induced Injection Pain: A Randomized Double-Blind Clinical Trial.

Background: Propofol is one of the most commonly used drugs in anesthesia, but administering it to patients often causes significant pain and discomfort. Numerous studies have been conducted on various methods to mitigate this adverse effect due to its prevalence. Methods: This study was conducted in 2025 at Kashani Hospital in Isfahan, Iran, involving 150 patients undergoing elective surgery who received propofol for anesthesia induction. They were randomly assigned to five groups: Normal saline (control), transcutaneous electrical nerve stimulation (TENS), acetaminophen, intravenous lidocaine, or intravenous fentanyl. Additionally, this randomized, double-blind, controlled clinical trial (allocation ratio 1:1) employed block randomization. Patients, along with the assessor and the data analyst, were blinded. Statistical analyses were performed using ANOVA, chi-square, and repeated-measures ANOVA. Pain during injection was rated using a 0 - 10 numerical scale. Results: There was no statistically significant difference in pain intensity between the intervention groups when comparing their mean pain scores (P > 0.05). However, in most comparisons, the normal saline group had the highest average pain scores. Conclusions: All interventions except saline reduced propofol injection pain. Secondary outcomes, including patient satisfaction, recovery time, and hemodynamic stability, were also evaluated, and no significant adverse effects were observed among the interventions. These findings support the use of multiple safe strategies to minimize discomfort during anesthesia induction.