Prostaglandins are a type of chemical that can be found in almost all tissues of mammals. Prostaglandins exist in cyclic form, and are composed of derivatives of fatty acids. They exert their functions both locally (in the basic vicinity of their production), as well as traveling through the bloodstream to act on distant target organs (in an endocrine manner). In fact, some prostaglandins are the "middle man" messengers between hormones and other components in cells. There are many types of prostaglandins, including those labeled PGA1, PGE1, PGE2, and PGI1.

Prostaglandins work on a number of different target tissues, including the uterus, ovaries, and fallopian tubes. Although the actions of prostaglandins are diverse depending upon the cell type in which they interact, they are best known for producing smooth muscle contraction. Prostaglandins are known to be involved in the initiation and maintenance of uterine contractions during labor, as well as in the production of the uncomfortable cramps occurring during menstrual periods. Prostaglandins are also involved in regulating the size of the blood vessels of the kidney. Prostaglandins affect the actions of the blood cells responsible for clotting (platelets). Prostaglandins are involved in the production of fever. Prostaglandins are also involved in the process of inflammation, and anti-inflammatory medications such as aspirin and ibuprofen work by interfering with the production of prostaglandins.