What the evidence says. Graded preliminary: a handful of small, short, largely developer-linked RCTs of one extract show modest signals on stress reactivity and cognition in healthy volunteers, but a meta-analysis found no effect on anxiety and no trial has tested people with clinical depression or anxiety. (Preliminary evidence: Early or small human trials; promising but not yet conclusive.)
What is Kanna (Sceletium)?
Kanna (Sceletium) (Sceletium tortuosum) is a sleep and mood supplement used for reduced stress reactivity (small acute trials). NutriDex grades the human evidence as Preliminary. Kanna (Sceletium tortuosum, also classed as Mesembryanthemum tortuosum) is a South African succulent traditionally chewed or fermented by San and Khoikhoi people to lift mood and ease stress. Its alkaloids, chiefly mesembrine and mesembrenone, block the serotonin transporter (the same target as SSRI antidepressants) and inhibit the enzyme PDE4. Most clinical data come from one standardised extract, Zembrin, at 25 mg/day, tested in small trials of healthy volunteers: a 3-week crossover (n=21) found better cognitive flexibility and executive function; single doses reduced amygdala threat reactivity on brain imaging (n=16) and lowered anxiety before a stress task (n=20); an 8-day trial in 60 young adults improved complex reaction tasks but not mood. A 2023 meta-analysis of four RCTs (117 participants) found no significant effect on anxiety, and no trial has tested people with diagnosed depression or anxiety disorders. Trials are small, short and mostly linked to the extract's developers.
Purported Benefits
✓Reduced stress reactivity (small acute trials)
✓Cognitive flexibility and executive function
✓Mood and sleep (self-reported, unconfirmed)
✓Traditional mood lifter
Dosing & Compounds
Typical Dose
Trials used a standardised extract (Zembrin, ~0.35–0.45% total alkaloids) at 25 mg once daily for up to 3 months; raw or fermented plant material is unstandardised and varies widely in alkaloid content.
Active Compounds
MesembrineMesembrenoneMesembrenolMesembranol
Safety & Cautions
⚠
In trials of up to 3 months, 25 mg/day of standardised extract was well tolerated, with occasional headache, nausea or drowsiness; long-term safety is unknown. Because mesembrine inhibits the serotonin transporter, combining kanna with SSRIs, SNRIs, MAOIs, tramadol, triptans, St John's wort, 5-HTP or MDMA carries a theoretical risk of serotonin toxicity (no confirmed cases published), so it should not be added to antidepressants without medical advice. Avoid in pregnancy, breastfeeding and bipolar disorder, and take care with alcohol or sedatives. Recreational concentrates and snuffed or smoked products are unstandardised and far stronger than trial doses. Educational only — always check with your doctor or pharmacist before combining Kanna (Sceletium) with any medicine.
Kanna (Sceletium) is most often taken for Reduced stress reactivity (small acute trials), Cognitive flexibility and executive function, Mood and sleep (self-reported, unconfirmed), Traditional mood lifter. South African succulent with mild, SSRI-like mood and stress effects.
Does Kanna (Sceletium) work — what does the evidence say?
Preliminary evidence. Early or small human trials; promising but not yet conclusive. Kanna (Sceletium tortuosum, also classed as Mesembryanthemum tortuosum) is a South African succulent traditionally chewed or fermented by San and Khoikhoi people to lift mood and ease stress. Its alkaloids, chiefly mesembrine and mesembrenone, block the serotonin transporter (the same target as SSRI antidepressants) and inhibit the enzyme PDE4. Most clinical data come from one standardised extract, Zembrin, at 25 mg/day, tested in small trials of healthy volunteers: a 3-week crossover (n=21) found better cognitive flexibility and executive function; single doses reduced amygdala threat reactivity on brain imaging (n=16) and lowered anxiety before a stress task (n=20); an 8-day trial in 60 young adults improved complex reaction tasks but not mood. A 2023 meta-analysis of four RCTs (117 participants) found no significant effect on anxiety, and no trial has tested people with diagnosed depression or anxiety disorders. Trials are small, short and mostly linked to the extract's developers.
What is the typical dose of Kanna (Sceletium)?
Trials used a standardised extract (Zembrin, ~0.35–0.45% total alkaloids) at 25 mg once daily for up to 3 months; raw or fermented plant material is unstandardised and varies widely in alkaloid content.
Is Kanna (Sceletium) safe? Any cautions or side effects?
In trials of up to 3 months, 25 mg/day of standardised extract was well tolerated, with occasional headache, nausea or drowsiness; long-term safety is unknown. Because mesembrine inhibits the serotonin transporter, combining kanna with SSRIs, SNRIs, MAOIs, tramadol, triptans, St John's wort, 5-HTP or MDMA carries a theoretical risk of serotonin toxicity (no confirmed cases published), so it should not be added to antidepressants without medical advice. Avoid in pregnancy, breastfeeding and bipolar disorder, and take care with alcohol or sedatives. Recreational concentrates and snuffed or smoked products are unstandardised and far stronger than trial doses.
How many studies support Kanna (Sceletium)?
NutriDex cites 9 sources for Kanna (Sceletium), graded "Preliminary".
Cite this page
APA
Peh, D. (2026). Kanna (Sceletium) (Sceletium tortuosum): Benefits, Dosage, Side Effects & Evidence. NutriDex — The Supplement Research Compendium. Retrieved 18 Oct 2026, from https://nutridex.info/s/kanna
BibTeX
@misc{nutridex_kanna,
author = {Peh, Daryl},
title = {Kanna (Sceletium) (Sceletium tortuosum): Benefits, Dosage, Side Effects \& Evidence},
year = {2026},
howpublished = {NutriDex --- The Supplement Research Compendium},
url = {https://nutridex.info/s/kanna},
note = {Reviewed by Dr Daryl Peh, MBBS Singapore, MMed FM. Accessed 2026-10-18}
}
For medical claims, citing the underlying primary studies linked above is preferred. NutriDex is an educational reference, not medical advice.