How effective are cannabinoids in treating arthritis?

THC and pain. Cannabinoids do have an effect on pain but no effect on inflammation. They work on the the cb 1 receptor for its effect. Unfortunately the cb 1 receptor is also involved in the reward process in addicts, drug misusers etc... So the risk of becoming addicted is very high. Really not a good idea to use this class.
Effective. Cannabinoids do relieve pain. However, I am unaware of any direct effect on inflammation. However, other drugs can relieve pain without exposing a person to the hazard of smoke or cognitive impairment.