Celecoxib is a non-steroidal anti-inflammatory drug that selectively inhibits cyclooxygenase-2 and is prescribed for severe pain and inflammation. The excellent therapeutic effects of celecoxib mean that it is frequently used clinically, including for women of child-bearing age. However, the prenatal effects of this compound have not been studied extensively in vertebrates. The present study examined the developmental toxicity of celecoxib using a frog embryo teratogenic assay-Xenopus (FETAX). In addition, we examined its effects on cell migration using co-cultures of human umbilical vein endothelial cells and 10T1/2 cells. These studies revealed that celecoxib induced concentration-dependent mortality and various malformations of the Xenopus internal organs, including gut miscoiling, haemorrhage, and oedema. Celecoxib also downregulated the expression of vascular wall markers (Msr and alpha smooth muscle actin) and other organ-specific markers (Nkx2.5, Cy1104 and 1FABP). In vitro co-culture studies revealed that celecoxib inhibited pericyte migration and differentiation into vascular smooth muscle cells. In conclusion, celecoxib was both toxic and teratogenic in Xenopus embryos, where it produced serious heart and vessel malformation by inhibiting vascular wall maturation and vascular network formation. (C) 2018 Published by Elsevier Inc.