Esophagogastroduodenoscopy (EGD) is the main examination in the upper gastrointestinal field. Aspiration pneumonia may happen if choking occurs during the EGD insertion, and the exam quality and efficacy may be affected if gag reflex occurs. The endoscopist may terminate the exam to avoid complications if the patient could not obey the orders. To reach the high quality of EGD examination and to avoid possible complications, the patient's comfort and compliance during the EGD examination are important. Sedation using propofol can improve the patient's comfort and compliance. However, in patients unsuitable for systemic anesthesia, local lidocaine spray at pharynx is performed instead. Until now, there is no standardization of the waiting time between lidocaine spray and the initiation of EGD. This study aimed to investigate the optimal timing of the initiation of esophagogastroduodenoscopy after lidocaine spray.