The bloody brittlegill was first described as Agaricus sanguinarius by Heinrich Christian Friedrich Schumacher in 1803, and redescribed under its current binomial name by mycologist Stephan Rauschert in 1989.

Both the specific epithets sanguinaria and sanguinea are derived from the Latin word sanguis ('blood'), a reference to the mushroom's colour.

The cream to pale ochre gills are adnate to slightly decurrent, narrow and forking.

It is widespread in the northern temperate zones, and is mycorrhizal with softwood trees, often Pinus (pine) in coniferous woodland, on sandy soils.

The active agent has not been identified but is thought to consist of sesquiterpenes, which have been isolated from Russula sardonia,[7] and the related genus Lactarius.