Investigators at the University of Bonn in Germany reported that the topical administration of THC significantly reduced inflammation in mice exposed to various chemical irritants. Researchers also reported that mice lacking endocannabinoid receptors demonstrated exacerbated allergic reactions to skin irritants, whereas mice with elevated levels of endocannabinoids showed a decreased reaction.

"These results demonstrate a protective role of the endocannabinoid system in [treating] contact allergy in the skin and suggest a target for therapeutic intervention," authors concluded.

Because cannabinoids are fat-soluble and are not readily absorbed through the skin, topical cannabis-based ointments lack the psychoactivity of inhaled marijuana or oral THC pills (e.g., Marinol).

Clinical trials performed in Europe demonstrate that the application of a cannabis-based ointment can greatly reduce uremic pruritus (mild to severe itching as a result of kidney disease) and xerosis (abnormal dryness of the skin) in hemodialysis patients.

A separate US study reports that the oral administration of THC can relieve pruritis in patients with liver disease.

Cannabis-based ointments were historically used to treat inflammation up until the early part of the 20th century.

For more information, please contact Paul Armentano, NORML Senior Policy Analyst, at: paul@norml.org. Full text of the study, "Attenuation of allergic contact dermatitis through the endocannabinoid system," appears in the June 2007 issue of Science. Additional information regarding cannabinoids and skin inflammation is available in the NORML report "Emerging Clinical Applications for Cannabis and Cannabinoids," online at: http://www.norml.org/index.cfm?Group_ID=7014.