Summary: A recent case report indicates that medical marijuana may offer rapid symptom relief for people with chronic itch. Researchers propose that THC interacts with brain and nervous system receptors, which can lower inflammation and nerve activity and, in turn, reduce the sensation of itch.
Source: Johns Hopkins Medicine
Chronic itch, medically known as chronic pruritus, is an ongoing, often debilitating urge to scratch that can significantly reduce quality of life. Effective, approved treatments are limited, which has left many patients reliant on off-label therapies or interventions that provide only partial relief.
A new case study from Johns Hopkins Medicine researchers suggests that a currently available option—medical marijuana—may help patients whose itch has not responded to standard therapies.
The team’s findings were reported on April 9, 2021, in JAMA Dermatology.
“Chronic itch can be especially difficult 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. Given the growing use of medical marijuana and emerging knowledge about the endocannabinoid system’s role in modulating itch and other sensations, the researchers decided to trial medical cannabis for a patient who had exhausted multiple treatment options.
The reported patient was an African American woman in her 60s with a decade-long history of persistent itch. She first sought care at the Johns Hopkins Itch Center for severe pruritus affecting her arms, legs and abdomen. Physical examination revealed numerous raised, hyperpigmented skin lesions consistent with chronic scratching.
The patient had previously tried several approaches, including systemic therapies, centrally acting nasal sprays, topical steroid creams and phototherapy, but experienced little or no lasting benefit. After other options failed, clinicians offered a trial of medical marijuana taken by inhalation or as a liquid preparation.
According to the report, the patient experienced near-immediate relief. Using a numerical rating scale in which 10 represented the worst possible itch and 0 represented no itch, she rated her symptoms at 10 before treatment. Within 10 minutes of initial administration of the medical cannabis, her itch score dropped to 4, and with continued use the sensation eventually resolved.
The researchers propose a plausible biological mechanism: tetrahydrocannabinol (THC), one of the principal active compounds in cannabis, binds to cannabinoid receptors found in the brain and nervous system. This interaction can modulate neural signaling and inflammatory processes that contribute to the perception of itch. By dampening those pathways, THC may reduce the intensity of itch sensations in some patients.
Kwatra and colleagues emphasize that this evidence comes from a single case, not a controlled clinical trial, and therefore should be interpreted cautiously. They note the urgent need for formal studies to determine appropriate dosing, long-term safety, and which subtypes of chronic itch are most likely to respond to cannabinoid-based therapies.
“Controlled studies are needed to determine dosing, efficacy and safety for medical marijuana in the treatment of various human itch subtypes,” Kwatra says. “Once rigorous trials are performed, we will better understand which patients are most likely to benefit from this therapy.”
This case report adds to growing clinical interest in cannabinoids as potential treatments for refractory sensory symptoms, including debilitating pruritus. For clinicians and patients, the findings highlight both the potential and the limits of current evidence: while anecdotal and early reports may be encouraging, well-designed randomized controlled trials are essential before medical marijuana can be recommended routinely for chronic itch.
About this chronic itch research news
Source: Johns Hopkins Medicine
Contact: Sheree-Monet Wisdom – Johns Hopkins Medicine
Image: The image is in the public domain
Original Research: Closed access. “Treatment of Chronic Pruritus With Medical Marijuana” by Shawn Kwatra et al., JAMA Dermatology (published April 9, 2021).
Abstract
Treatment of Chronic Pruritus With Medical Marijuana
Chronic pruritus is a burdensome symptom that can arise from dermatologic, neurologic and systemic conditions. It is frequently resistant to conventional therapies and can severely impair quality of life. Currently, there are few, if any, U.S. Food and Drug Administration–approved treatments specifically for chronic itch, which often forces clinicians and patients to use off-label medications.
This article describes a single-case report of successful use of medical marijuana to treat chronic pruritus in a patient whose symptoms had not responded to multiple other interventions. The case supports further clinical investigation of cannabinoid-based approaches to managing persistent itch.