Sphingosine (2-amino-4-octadecene-1,3-diol) is an 18-carbon amino alcohol with an unsaturated hydrocarbon chain, which forms a primary part of sphingolipids, a class of cell membrane lipids that include sphingomyelin, an important phospholipid.

Sphingosine can be phosphorylated in vivo via two kinases, sphingosine kinase type 1 and sphingosine kinase type 2. This leads to the formation of sphingosine-1-phosphate, a potent signaling lipid.Sphingolipid metabolites, such as ceramide, sphingosine and sphingosine-1-phosphate, are lipid signaling molecules involved in diverse cellular processes.

There is no direct route of synthesis from sphinganine to sphingosine; it has to be acylated first to dihydroceramide, which is then dehydrogenated to ceramide. Sphingosine is formed via degradation of sphingolipid in the lysosome.