Treatment-resistant chronic pruritus relieved with medical cannabis


Findings from a case study from Johns Hopkins University School of Medicine suggest that medical cannabis may be an effective treatment for chronic pruritus.

The patient in the reported case is a Black woman in her 60s who had a 10-year history of chronic pruritus. She presented at the Johns Hopkins Itch Center with complaints of extreme pruritus on her arms, legs and stomach. Examining physicians found numerous hyperpigmented, raised skin lesions on her body. They unsuccessfully tried a number of treatments, including several systemic therapies, centrally acting nasal sprays, steroid creams and phototherapy.

“Chronic itch can be an especially difficult condition to treat, with off-label therapeutics often utilized,” said the case report’s senior author, Dr. Shawn Kwatra, in a press release. “With the increased utilization of medical marijuana and our knowledge of the role of the endocannabinoid system [a complex cell-signalling system that regulates a variety of functions in the body] in chronic itch, we decided to try medical marijuana with a patient who failed several therapies and had few options left.” Dr. Kwatra is an assistant professor of dermatology at the Johns Hopkins University School of Medicine in Baltimore.

Treatment with medical cannabis provided the patient with rapid improvement in her pruritus symptoms.

“We had the patient rate her symptoms using a numerical rating scale, where 10 is the worst itch and zero is no itch at all,” Dr. Kwatra said. “She started at 10 but dropped to four within 10 minutes after initial administration of the medical marijuana. With continued use of the cannabis, the patient’s itch disappeared altogether.”

The researchers say that they believe that tetrahydrocannabinol (THC) attaches to brain receptors that influence inflammation and nervous system activity, which they say could lead to a reduction in skin sensations such as itchiness.

Dr. Kwatra said that although conclusive studies have yet to be done to validate medical marijuana as an effective measure for the relief of previously unmanageable itch, he believes it warrants further clinical trials.

“Controlled studies are needed to determine dosing, efficacy and safety for medical marijuana in the treatment of various human itch subtypes, and once those are performed, we will better understand which patients are most likely to benefit from this therapy,” he said.

The case was published online in JAMA Dermatology (April 9, 2021).