Almost nobody selling this material writes about its risks, which is why the search results for this question are split between alarmist news coverage and forum speculation. Neither is much use.

This is an overview of what the published literature and Health Canada actually document. It is written by a company with an obvious commercial interest in the answer being reassuring, so everything below is sourced and you should check it.

What Health Canada lists

Health Canada's stated position is that kratom "may pose serious health risks when swallowed or inhaled," and it names: drowsiness, nausea, vomiting, seizures, liver toxicity, and excessively rapid heartbeat. It adds that kratom "has been linked to both narcotic and stimulant-like effects, and has potential for abuse and dependence."

That is a regulator's summary, drawn largely from case reports and adverse event data. It is worth taking seriously, and it is also worth understanding which items rest on solid evidence and which rest on a handful of cases where other substances were present.

The common and well-documented effects

Gastrointestinal. Nausea, vomiting and constipation are the most consistently reported adverse effects across surveys. In the largest survey of users to date, published in Drug and Alcohol Dependence in 2017 with 8,049 respondents, negative effects were predominantly gastrointestinal and were dose-dependent, appearing mainly at higher doses and higher weekly frequency. Constipation in particular is unsurprising given the pharmacology.

Drowsiness and sedation. Widely reported, dose-related.

These are the effects with the strongest evidence base, and notably they are the least dangerous ones.

The serious ones

Liver injury. This is real and it is the risk we think is most under-discussed in this category. In the Drug-Induced Liver Injury Network prospective study, eight of 404 cases of herbal and dietary supplement associated liver injury between 2004 and 2018 involved kratom-containing products, seven of them convincingly attributed. The pattern is typically cholestatic, and onset is usually weeks rather than days after starting. We cover this in detail in a dedicated article, including what the early signs look like.

Dependence and withdrawal. Documented in both survey and clinical literature. A withdrawal syndrome exists and is generally described as milder than that of classical opioids, but "milder" is not "absent." Covered separately.

Seizures. Reported in case literature, frequently in the context of polysubstance use or very high doses. The evidence here is weaker than for liver injury, and causation is harder to establish when other substances are involved.

Tachycardia. Reported, generally dose-related.

The interaction problem

This is the risk least likely to appear on a vendor site and arguably the most practically important.

Mitragynine inhibits several cytochrome P450 enzymes, notably CYP2D6 and CYP3A4, which are responsible for metabolising a very large share of common prescription medications. Inhibiting them can raise the blood levels of other drugs a person is taking.

This matters most for exactly the people most likely to be interested in this material: people already taking several prescription medications. We have given it its own article.

What the mortality data actually shows

The headline figures circulated in news coverage are usually presented without the context that changes their meaning.

The CDC examined 27,338 overdose deaths across 27 states between July 2016 and December 2017. Kratom was detected in 152 of them, which is 0.56%. It was determined to be a cause of death in 91. Of those 91, only seven had kratom as the only substance detected among those tested for. Fentanyl was present in around 65% of the kratom-positive deaths and heroin in roughly a third.

Two conclusions follow, and both are true at once. Fatal outcomes involving kratom alone are rare. And combination, particularly with opioids, benzodiazepines or alcohol, is the circumstance in which nearly all of these deaths occurred.

Where the evidence genuinely is thin

We should be as clear about the gaps as about the findings.

There are no randomised controlled trials of kratom in humans for any indication. The survey data everyone quotes, including the figures we cite above, comes from self-selected samples of current users, which builds in survivorship bias: people who tried it and found it unhelpful or unpleasant stopped, and are not in the sample. The authors of those surveys said so themselves.

The first human study under an FDA-regulated drug development programme, an NIH phase I trial of purified mitragynine, only had its investigational new drug application take effect in 2026. A phase I trial in healthy volunteers is a safety and dosing study. It is the beginning of an evidence base, not the arrival of one.

Why we publish this

Because it is true, because people search for it and deserve an accurate answer, and because a company that will not tell you the risks of its own product has told you something important about itself.

Sources

This is information, not medical advice. If you are concerned about a health effect you are experiencing, speak to a doctor or pharmacist and tell them what you have taken. Verified Botanicals sells botanical material for reference and research purposes only. Not intended for human consumption.