Last Updated: September 28 2022

Also known as Kanna, sceletium tortusoum is a herb that is traditionally chewed prior to stressing endeavours. It suggest that it may play a role in reducing state anxiety although more evidence is required.

Kanna is most often used for


Sceletium tortuosum is a herb known as Kanna which is traditionally known as a psychoactive herb. It is not known to be hallucinogenic nor habit forming but is taken prior to stressing events such as hunting (traditional use) for its cognitive effects.

Limited evidence does not suggest any improvement in reaction time or many parameters of cognitive performance such as memory although there may be an attenuation of state anxiety. State anxiety refers to the increase in anxiety experienced during a high stress event (such as a cognitive or physical test) and administration of Kanna prior to these events may reduce how much anxiety is experienced and thus the deleterious effects of anxiety on performance.

While the mechanisms as to why Kanna exerts these effects is not conclusively known, it is known to influence the amygdala of the brain (a brain region central in emotional processing) and is known to also have inhibitory effects on both the serotonin transporter as well as an enzyme known as phosphodiesterase 4 (PDE4); both of these proteins existing in the amygdala.

While there is not enough evidence to currently recommend Kanna, its main role of reducing state anxiety appears promising and there are a few other claims (such as antidepressive effects) which remain untested.

What else is Kanna known as?
Note that Kanna is also known as:
  • Kanna
  • Channa
  • Kougoed
  • Sceletium Tortuosum
Dosage information

Currently studies using Kanna have used the brand name Zembrin® at doses of 8-25mg prior to cognitive testing. This brand name is a 2:1 concentration of Kanna based on dry weight and is considered equivalent to 16-50mg of the dry weight of the plant itself.

Kanna has been studied as oral administration (capsules) but traditionally the leaves have been chewed and saliva swallowed for similar effects.

Optimal frequency of dosing (ie. either only on testing days or daily) is currently not known.

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1.^Smith MT1, Crouch NR, Gericke N, Hirst MPsychoactive constituents of the genus Sceletium N.E.Br. and other Mesembryanthemaceae: a reviewJ Ethnopharmacol.(1996 Mar)
2.^Stafford GI1, Pedersen ME, van Staden J, Jäger AKReview on plants with CNS-effects used in traditional South African medicine against mental diseasesJ Ethnopharmacol.(2008 Oct 28)
5.^Terburg D1, Syal S, Rosenberger LA, Heany S, Phillips N, Gericke N, Stein DJ, van Honk JAcute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala and its connection to the hypothalamusNeuropsychopharmacology.(2013 Dec)
6.^Chiu S1, Gericke N2, Farina-Woodbury M3, Badmaev V4, Raheb H5, Terpstra K5, Antongiorgi J3, Bureau Y5, Cernovsky Z1, Hou J5, Sanchez V5, Williams M5, Copen J6, Husni M7, Goble L5Proof-of-Concept Randomized Controlled Study of Cognition Effects of the Proprietary Extract Sceletium tortuosum (Zembrin) Targeting Phosphodiesterase-4 in Cognitively Healthy Subjects: Implications for Alzheimer's DementiaEvid Based Complement Alternat Med.(2014)
10.^Gericke N1, Viljoen AMSceletium--a review updateJ Ethnopharmacol.(2008 Oct 28)
11.^Murbach TS1, Hirka G2, Szakonyiné IP2, Gericke N3, Endres JR4A toxicological safety assessment of a standardized extract of Sceletium tortuosum (Zembrin(®)) in ratsFood Chem Toxicol.(2014 Dec)
13.^Shikanga EA1, Hamman JH, Chen W, Combrinck S, Gericke N, Viljoen AMIn vitro permeation of mesembrine alkaloids from Sceletium tortuosum across porcine buccal, sublingual, and intestinal mucosaPlanta Med.(2012 Feb)
15.^Pringle A1, Browning M, Cowen PJ, Harmer CJA cognitive neuropsychological model of antidepressant drug actionProg Neuropsychopharmacol Biol Psychiatry.(2011 Aug 15)
23.^Loria MJ1, Ali Z2, Abe N2, Sufka KJ3, Khan IA2Effects of Sceletium tortuosum in ratsJ Ethnopharmacol.(2014 Aug 8)