Kanna (Sceletium tortuosum) has centuries of traditional use and a small but growing body of modern research. This article covers what that research reports about side effects, the one interaction that matters most, and who should not take kanna.
The interaction that matters: serotonin
Kanna's alkaloids have serotonergic activity. That is the basis of what it does — and the basis of its most important restriction.
Do not use kanna if you take an SSRI, SNRI, MAO inhibitor, tricyclic antidepressant, lithium, a triptan, tramadol, dextromethorphan, St. John's Wort, 5-HTP, or any other serotonergic medication or supplement, unless you have first consulted the prescribing clinician. Combining serotonergic substances can cause serotonin syndrome, a rare but serious condition.
This is not fine print. It is the single most important thing to know before taking kanna, and it applies to supplements as much as prescriptions — St. John's Wort and 5-HTP count.
What the research reports
Clinical studies on kanna extracts — all run in healthy adults — report good tolerability at servings up to 25mg of a standardized research extract. In the first human brain-imaging study, participants reported no side effects from a single 25mg serving. In a pilot exercise study using 25mg daily for three days, none were reported either.
The side effects that do appear in the wider literature are uncommon and mild: headache and nausea, more likely at larger servings.
Who should not take kanna
Kanna is not for anyone under 18, or for people who are pregnant or nursing. Anyone with a diagnosed medical condition should consult a physician before use. Do not drive or operate machinery until you know how kanna affects you.
Sensible use
Start with one serving — for our extract powders that is 25mg, and effects run two to three hours. Do not stack kanna with other serotonergic supplements. If you experience adverse effects, stop taking it and seek medical attention.
Serving sizes and formats are covered in A Beginner's Guide To Kanna.
†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
