Russia's leading anti-drug crusader says the abuse of synthetic marijuana is turning into a "horrible" epidemic in his country.

Experts say a range of hallucinogens known as "spice" are very hard to kick, and addicts lose sleep, weight and get kidney and brain disorders from them.

Evgeny Roizman, who spoke Wednesday, heads a rehabilitation clinic in the central city of Ekaterinburg.

Concerned about the spread of "spice," Russian drug enforcement agencies have banned several of its chemical ingredients. But producers can easily change the chemical makeup to come up with new brands, which are advertised online and widely sold across Russia.

Components of "spice" have been banned in several European nations and in parts of the United States.