The man-made drug, often known as Spice or Black Mamba, mimics the effects of cannabis but is produced in illegal labs from a cocktail of chemicals and can be dozens of times stronger.
Jails are "awash" with the substance, according to the Prison Officers Association (POA), with reports of stashes of the drug being dropped by drone or thrown over walls, and prison officers attacked by high inmates.
Peter Clarke, chief inspector of prisons, said violence and bullying are increasing as addicted inmates get into debt with dealers.
It is "getting worse, not better", Mr Clarke told the Guardian.
"Prison staff have told me that the effect on individuals and prisons as a whole is unlike anything they have seen before."