Thromboxane is a member of the family of lipids known as eicosanoids. It is produced in platelets by thromboxane synthetase , which is produced from the endoperoxides by the cyclooxygenase (COX) enzyme from arachidonic acid.

Thromboxane is a vasoconstrictor and facilitates the clumping of platelets. It is in homeostatic balance in the circulatory system with prostacyclin, a related compound. The widely-used drug aspirin acts by inhibiting the ability of the COX enzyme to synthesize the precursors of thromboxane within platelets.

Thromboxane is named for its role in clot formation (thrombosis).