Chronic itch—known clinically as chronic pruritus—is characterized as an
unrelenting and sometimes even debilitating sensation to itch, and often
lowers the quality of life for those who suffer with it. Treating the
condition has been difficult because there are few Food and Drug
Administration-approved therapies. Now, a recent case study by Johns Hopkins
Medicine researchers provides evidence that a promising option for patients
with chronic itch may already be available: medical marijuana (cannabis).
A report on the team's findings was published in JAMA Dermatology.
"Chronic itch can be an especially difficult condition to treat, with
off-label therapeutics often utilized," says Shawn Kwatra, M.D., assistant
professor of dermatology at the Johns Hopkins University School of Medicine.
"With the increased utilization of medical marijuana and our knowledge of
the role of the endocannabinoid system [a complex cell-signaling 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."
Kwatra and his colleagues examined an African American woman in her 60s with
a 10-year history of chronic itch. The patient initially arrived at the
Johns Hopkins Itch Center with complaints of extreme pruritus on her arms,
legs and stomach. Upon a skin examination, numerous hyperpigmented, raised
skin lesions were revealed. Several treatments were offered to the
patient—including several systemic therapies, centrally acting nasal sprays,
steroid creams and phototherapy—but they all failed.
Kwatra says that using medical marijuana—either by smoking or in liquid form
—provided the woman with nearly instantaneous improvement.
"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," Kwatra says. "She started
at 10 but dropped to 4 within 10 minutes after initial administration of the
medical marijuana. With continued use of the cannabis, the patient's itch
disappeared altogether."
The researchers believe that one of the active ingredients in medical
marijuana, tetrahydrocannabinol—commonly known by its abbreviation
THC—attaches itself to brain receptors that influence the nervous system.
When this occurs, inflammation and nervous system activity decrease, which
also could lead to a reduction in skin sensations such as itchiness.
Kwatra says 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 says.
Reference:
Youkyung S. Roh et al. Treatment of Chronic Pruritus With Medical Marijuana,
JAMA Dermatology (2021). DOI:
10.1001/jamadermatol.2021.1194
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Medical Science