The effect of dexamethasone on post-dural puncture headache (PDPH) after spinal anesthesia has not been well elucidated. This randomized, double-blind, placebo-controlled trial was carried out in patients undergoing a cesarean at the Qilu Hospital, Shandong University. The subjects were randomly divided into a placebo and a dexamethasone group. The incidences of PDPH on the first, second, third and seventh postoperative day were studied, and the severity of PDPH was assessed using a visual analog scale. Studies in PubMed, Embase and the Cochrane Library database were searched and included in the present meta-analysis. Summary estimates of weighted mean differences and 95 % confidence intervals (CIs) were obtained using random-effects models. We included 307 participants in the dexamethasone group and 309 in the placebo group for analysis. The results indicated that prophylactic administration of 8 mg dexamethasone did not have any protective effect against PDPH (31 vs. 18, P = 0.054) and even increased the incidence of PDPH in the first 24 h in parturient patients (25 vs. 11, P = 0.016). Furthermore, the meta-analysis also showed that dexamethasone did not prevent the incidence of PDPH in the postoperative follow-up days (RR 1.05; 95 % CI 0.46-2.38; P = 0.91) and may even have increased the trend in the first 24 h. Prophylactic administration of 8 mg dexamethasone does not have any protective effect against PDPH and may even increase the incidence of PDPH in the first 24 h in patients with spinal anesthesia.