Safranin is used as a counterstain in some staining protocols, colouring cell nuclei red.

There is also trimethyl safranin, which has an added methyl group in the ortho- position (see Arene substitution pattern) of the lower ring.

Both compounds behave essentially identically in biological staining applications, and most manufacturers of safranin do not distinguish between the two.

They are crystalline solids showing a characteristic green metallic lustre; they are readily soluble in water and dye red or violet.

It can be readily diazotized, and the diazonium salt when boiled with alcohol yields aposafranine or benzene induline, C18H12N3.