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Systematic Review of Kratom: Risks and Benefits for Mental Health


Reviewed: Swogger MT, Walsh Z. Kratom use and mental health: a systematic review. Drug Alcohol Depend. 2018;183:134-140.

In this systematic review of the scant literature on the effects of kratom (Mitragyna speciosa, Rubiaceae) leaf on mental health, authors Marc Swogger, PhD, and Zach Walsh, PhD, contend that the 2016 public warnings by the US Centers for Disease Control and Prevention (CDC) and Drug Enforcement Administration (DEA) of possible kratom-induced psychosis or death are unsupported by evidence. The authors are clinical psychologists with a strong record of research and publications on the behavioral and mental health effects of psychoactive substances. According to the authors, criminalizing kratom would increase potential harms, restrict research, and deny access to possible benefits. Reminiscent of the 1930s criminalization of “marihuana” (cannabis [Cannabis spp., Cannabaceae]), the authors believe that some government statements and media stories have fomented “drug hysteria” regarding kratom.

Kratom leaves have been used for centuries in Southeast Asia for pain, cough, and diarrhea; enhanced energy and stamina; and as an opioid substitute or to relieve opioid withdrawal symptoms. Traditionally chewed fresh or taken in a water infusion, leaves may also be smoked or vaporized. Kratom products (e.g., extracts, capsules, gums, and powders) are widely available in North America and Europe, and via the internet. Processed, concentrated products raise new concerns about potential adverse effects (AEs), making kratom research particularly timely.

Many of kratom’s potential risks and benefits are in the realm of mental health. The authors searched for reports that were published between January 1960 and February 2017.* Case studies were excluded, as were studies with inadequately described methods. Of 49 initial results, after excluding duplicates and those that did not meet criteria, 13 cross-sectional or retrospective studies were reviewed. Nine reported on user surveys in Thailand or Malaysia; two on calls to US poison control centers; and two on US surveys on kratom use. The presented results pertain to harm reduction, mood, and AEs.

In the United States, misuse of prescribed and prohibited opioids has reached “catastrophic” levels, according to the authors. They state that new approaches to opioid harm reduction and cessation are needed. Harm from drug abuse can be reduced, for example, by substituting substances with similar effects but that cause less severe harm (e.g., methadone or buprenorphine use for opioid addiction). Two Malaysian studies suggest that kratom may have potential in opioid substitution. In one study of 136 users, most of whom were men who reported low education and/or a history of drug use, 90% used kratom as an opioid substitute, and 84% said it helped with withdrawal symptoms. In the other study of 293 men, who were generally younger (mean age = 28) and better educated (66% reported at least an upper secondary education) than those in the first study, 15% used kratom to reduce or stop use of “illicit substances” (e.g., opioids, cannabis) and/or manage withdrawal. Of 8,049 respondents to a US-based internet survey, almost half said they used kratom to reduce or stop opioid use. A minimum dose of 5 g was deemed effective by these respondents. Nearly half were women, a population traditionally underrepresented in kratom research, and 80% reported some college education. This study also reported on the use of kratom for mood effects. Respondents who had Medicare, Medicaid, no insurance, or were self-insured were more likely to use kratom for its mood-enhancing and opioid-substituting effects. Female gender and being married were negatively associated with both uses.

Kratom is reported as energizing at low doses and calming at higher ones. In one of the Malaysian studies cited above, 28% of 293 male users said that kratom boosted energy and alertness, and 26% said that it brought about euphoria, relaxation, or contentment. Of 161 kratom users who responded to a US-based survey, 30% reported an enhanced sense of well-being and 9% reported increased energy. Kratom users often mention its relaxing and anxiety-reducing effects, but none of the reviewed studies specifically addressed kratom’s anxiolytic effects, especially relative to sedation or impaired social motivation, which are drawbacks to some common anxiolytics. Drowsiness and sedation were reported by 19.4% of 660 people who called US poison control centers after taking kratom (2010-2015). However, more than 40% of those who reported drowsiness and sedation had used other substances concurrently. Of the 8,049 respondents in the large US-based survey mentioned previously, 79.4% reported more energy, 75.6% reported less depressed mood, and 74.3% reported less anxiety. Energizing effects were reported with intake of 1 g or less; benefits to depression and anxiety were reported with intake up to 5 g.

Psychosocial AEs of kratom use typically are related to tolerance, withdrawal, and difficulty in abstaining. In ethnically and culturally diverse studies, reported withdrawal symptoms include fatigue, craving, tremors, muscle cramps/aches, insomnia, anxiety/tension, depressed mood, nausea/vomiting, hot flashes/sweating, diarrhea, and watery eyes. These symptoms resemble symptoms of opioid withdrawal but lack comparable intensity or duration. There is no evidence that kratom causes psychopathology or aggression. While 4% of subjects in a Malaysian study who were asked specifically about hallucinations had experienced such visual anomalies, these may have been caused by other substances ingested, existing psychopathology, or respondents confusing “hallucinations” with a mild visual perception enhancement, which has been reported as a kratom effect. The authors conclude that “kratom use appears to have several important mental health benefits that warrant further study. Kratom dependence is a risk for some people, though the dependence syndrome appears to be mild in its psychosocial and physiological effects relative to that of opioids.”

* It is unclear if the authors searched for reports on kratom alone or included its alkaloids mitragynine and 7-hydroxymitragynine, which are unmentioned in their review

—Mariann Garner-Wizard