BACKGROUND Intravenous ciprofol is a short-acting sedative with minimal respiratory and circulatory suppression and limited analgesia. Intravenous lidocaine provides analgesia during surgical procedures. This study included 70 patients who underwent gastroscopy with analgesia and aimed to evaluate the effects of intravenous lidocaine on the dose of ciprofol required to produce 50% of the maximal effect (ED50). MATERIAL AND METHODS Seventy patients scheduled for elective painless gastroscopy were randomly assigned into 2 groups: group L (n=35, received ciprofol and 1.5 mg/kg lidocaine) and group S (n=35, received ciprofol and normal saline). The primary outcomes measured were the ED50 and the 95% effective dose (ED95) of ciprofol, determined using the modified up-down sequential method and Probit analysis. Secondary outcomes included induction, operation, and recovery times; monitoring of vital signs such as mean arterial pressure, heart rate, and oxygen saturation; and evaluation of postoperative adverse reactions, including sore throat, nausea, vomiting, abdominal pain, and satisfaction scores from endoscopists and anesthesiologists. RESULTS The ED50 of ciprofol in group L was 0.315 mg/kg (95% CI, 0.291-0.342 mg/kg), which was significantly lower than that in group S, 0.42 mg/kg (95% CI, 0.371-0.491 mg/kg). Additionally, group L exhibited shorter induction and recovery times, a lower incidence of postoperative sore throat, and a temporary drop in blood pressure following induction. CONCLUSIONS Intravenous lidocaine during painless gastroscopy reduces the required ciprofol dose, shortens induction and recovery times, and lowers the incidence of postoperative complications, such as sore throat. These findings support its effective role in improving sedation quality and patient outcomes during gastroscopy.