Swogger MT, Walsh Z. Kratom use and mental health: a systematic review. Drug Alcohol Depend. February 1, 2018;183:134-140.
In a systematic review of the scant literature on kratom's (Mitragyna speciosa, Rubiaceae) effects on mental health, the authors argue 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. According to the authors, criminalizing kratom possession and use would increase potential harms, restrict research, and deny access to possible benefits. Reminiscent of the 1930s criminalization of "marihuana" (cannabis [Cannabis sativa, Cannabaceae]; see Schedule I, Controlled Substances Act), some government statements and media stories have fomented "drug hysteria."
Kratom leaves have been used for centuries in Southeast Asia, Malaysia, and the Philippines 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 and/or vaporized. Kratom products (e.g., extracts, capsules, gums, and powders) are widely available in North America, Europe, and via the internet. Processed, concentrated products raise new concerns about potential adverse effects (AEs), making kratom research particularly timely. In the United States, abuse of prescribed and prohibited opioids has reached "catastrophic" levels. New approaches to harm reduction and cessation are needed. Many of kratom's potential risks and benefits are in the realm of mental health. The authors searched for reports encompassing broad emotional, psychological, and social domains that were published between January 1960 and February 2017.* Case studies were excluded, as were those that inadequately described their methods. Of 49 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, calls to US poison control centers; and two, US surveys on kratom use. Results are presented pertaining to harm reduction, mood, and AEs.
Harm from drug abuse can be reduced by substituting substances with similar effects but less severe harm, e.g., methadone or buprenorphine use for opioid addiction. Evidence indicates that cannabis can substitute for alcohol, opioids, and cocaine (from Erythroxylum spp., Erythroxylaceae). Two Malaysian studies signal kratom's potential in opioid substitution. In one, of 136 users, mostly men with low education and/or prior drug use history, 90% used kratom as an opioid substitute, and 84% said it helped with withdrawal. In the other study, of 293 men who were younger and more educated than in the first, 15% used kratom to reduce or stop use of "illicit substances" (opioids, cannabis) and/or manage withdrawal. Of 8049 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, underrepresented in kratom research, and 80% had some college education. This study also reported on use of kratom for its mood effects; for these and its opioid-substituting effect, use was more likely for respondents who had Medicare, Medicaid, or no/self-insurance. 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 kratom boosted energy and alertness; 26% mentioned euphoria, relaxation, or contentment. Of 161 users who responded to a US-based survey, 30% reported an enhanced sense of well-being; 9%, increased energy. Kratom users often mention relaxation and reduced anxiety, but no study specifically addressed kratom's anxiolytic effects, especially relative to sedation or impaired social motivation, drawbacks to some common anxiolytics. Drowsiness and sedation were reported by 19.4% of 660 people who called poison control centers after taking kratom (2010-2015), but >40% had used other substances concurrently. In the large US-based survey mentioned above, of 8049 respondents, 79.4% reported more energy; 75.6%, less depressed mood; and 74.3%, less anxiety. Energizing effects were reported with intake of ≤1 g; benefits to depression and anxiety, up to 5 g. Withdrawal symptoms, on the contrary, may include depression, anxiety, irritability, agitation, and hostility.
Psychosocial AEs of kratom use seem related solely to tolerance, withdrawal, and difficulty in abstaining. In ethnically and culturally diverse studies, withdrawal symptoms include fatigue, craving, tremors, muscle cramps/aches, insomnia, anxiety/tension, depressed mood, nausea/vomiting, hot flashes/sweating, diarrhea, and watery eyes, strikingly resembling symptoms of opioid withdrawal but lacking comparable intensity or duration. There is no evidence that kratom causes any psychopathology or aggression. While 4% of subjects in a Malaysian study who were asked specifically about hallucinations had experienced such visual anomalies, these may be due to other substances ingested, existing psychopathology, or confusing "hallucinations" with a mild visual perception enhancement reported as a kratom effect. While the "most robust finding" of this review may be "that the study of kratom's effects on humans, and mental health in particular, is in its infancy," the authors amply demonstrate the folly of premature, ill-informed regulation of a natural product with no significant harm to public health and the potential to reduce opioid dependency, safely manage pain, and relieve anxiety.
* It is unclear if the authors searched for reports on kratom alone or included its main alkaloids mitragynine and 7-hydroxymitragynine, unmentioned in their review. Also, among search terms listed (anxiety, posttraumatic stress, etc.), sexual dysfunction is not mentioned, and kratom's effects on libido and sexual performance are not discussed; however, Table 1 mentions increased sexual desire reported as a benefit of kratom use in one study.