Renew have published a leaflet on Spice and other synthetic cannabinoids.  They can be highly addictive, toxic drugs that have been known to cause overdose and fatalities.
There is no safe way to use spice, it is not the same as cannabis – it is more potent, more unpredictable and more dangerous.
Spice is very addictive – regular use of spice can lead to a dependency and withdrawal when not using.

Download the information leaflet