"Generally, as analgesics, cannabinoids have minimal toxicity and present no risk of lethal overdose.48 End-organ failure secondary to medication effect has not been described and no routine laboratory monitoring is required in patients taking these medications."

Source

Aggarwal, Sunil K., "Cannabinergic Pain Medicine: A Concise Clinical Primer and Survey of Randomized-controlled Trial Results," Clinical Journal of Pain (Philadelphia, PA: February 23, 2012), p. 3.
http://www.ncbi.nlm.nih.gov/p…