Background: Spinal anesthesia is the most commonly used method for elective cesarean section, which is a popular technique due to its simplicity, reliability, and speed to achieve adequate anesthesia. Headache following dura perforation is the most important delayed complication following spinal and epidural anesthesia. Objectives: To evaluate the impact of low-dose intravenous ketamine in patients undergoing cesarean section under spinal anesthesia on the prevention of dura perforation headache (PDPH). Methods: This clinical trial study was performed on 64 pregnant women undergoing cesarean section at Vali-e-Asr Hospital. The patients were divided into two groups. In the case group, 0.15 mg/kg body weight ketamine was injected intravenously and in the control group, normal saline was used as the placebo. The incidence of headache and its severity at one, 4, 12, and 24 hours postoperatively, nausea and its severity were also measured and compared. Independent t-test, Mann-Whitney U and chi-square tests were used. A P value < 0.05 was considered statistically significant. Results: The data revealed that low dose intravenous ketamine significantly decreased patients' headaches (P = 0.001), the sensation of pruritus (P = 0.009), and the need for analgesic (P = 0.001). Furthermore, the sensation of postoperative nausea was less in the case group. The patients in the case and control groups had no significant difference in terms of hypertension or bradycardia (P = 0.717 and 0.939, respectively). Conclusions: The injection of ketamine as a premedication in the cesarean section can reduce the severity of postoperative headache in mothers. Therefore, it is recommended to use ketamine as an anti-headache drug in pregnant women.