Sutherlandia and Kanna (Sceletium): Traditional Use and Evidence
Sutherlandia and kanna (Sceletium) are southern African plants with long traditional use. What trials in people found, how kanna may overlap with antidepressants, and key cautions.
Content last updated . This page has not been medically reviewed.
Two plants, two stories
Sutherlandia (Sutherlandia frutescens, also placed in the genus Lessertia) and kanna (Sceletium tortuosum, also called kougoed) are both plants of southern Africa with long histories of traditional use. They are sold today as supplements, so people often ask whether the traditional claims hold up. This page describes the traditional use in its own terms, then separates what was measured in the lab from what was tested in people. For HIV-related claims about Sutherlandia, see African herbs and HIV or AIDS claims.Sutherlandia: traditional use
A 2008 review describes Sutherlandia as a popular plant in traditional medicine, native to South Africa, Lesotho, southern Namibia and southeastern Botswana. It lists many uses, including poor appetite, stomach complaints, colds, fever, kidney conditions, stress and anxiety, and use as a bitter tonic and an anti-stress medicine called 'musa-pelo. It also records use as a cancer tonic since at least 1895. [1] The review does not name the specific peoples behind each use, and this page does not guess. Historical use is not evidence of safety or benefit; see why a long history of use is not proof.Sutherlandia: what trials in people found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Safety in healthy adults | A randomized, double-blind, placebo-controlled pilot of 25 adults over 3 months (12 on Sutherlandia, 13 on placebo) found no significant differences in adverse events. Participants on Sutherlandia reported better appetite. [2] | Promising but limited (small, safety-focused) |
| Safety in adults with HIV | A 24-week trial analyzed 107 adults with HIV. Sutherlandia did not change viral load or CD4 count. Days of infection-related events were higher in the Sutherlandia group (p = 0.045), attributed to two tuberculosis cases in people taking isoniazid preventive therapy. The authors called for study of a possible interaction. [3] | Mixed; no benefit shown, a possible interaction signal |
| Treating cancer or any other disease | The 2008 review said preclinical data justified controlled clinical studies. [1] We found no completed trial showing benefit for any disease. | Insufficient evidence (cancer use is traditional use only) |
| Effect on how the body processes medicines | A lab study found Sutherlandia and African potato extracts affected an enzyme (CYP3A4) and a transporter (P-glycoprotein) involved in handling antiretroviral drugs. The authors warned this could risk treatment failure or toxicity. [4] | Preclinical (lab study) |
| Effect on atazanavir blood levels in people | In a small study of 12 healthy men, 12 days of Sutherlandia was followed by lower blood levels of the HIV medicine atazanavir (about 20 percent lower on average). The authors concluded it could lead to too little medicine in the blood. [14] | Promising but limited as a warning sign (very small study, healthy men) |
A 2005 review of Sutherlandia and African potato found no clinical trials of efficacy for HIV and low-level evidence of harm from drug interactions. [5]
Kanna (Sceletium): traditional use
Reviews describe kanna as a plant used by the San and Khoikhoi peoples, traditionally chewed (and in one review also smoked). Reported uses include relieving thirst, hunger, fatigue, toothache and abdominal pain, and as a mood-lifter, along with social and spiritual purposes. [6][7] Some of these uses are social or spiritual. This site does not describe how kanna is prepared or used in those settings; the communities and the scholars who work with them are the right sources.Kanna: lab findings and trials in people
A 2011 lab study found a standardized kanna extract blocked the serotonin transporter and an enzyme called PDE4, and that mesembrine was the most active alkaloid at the serotonin transporter. The authors suggested this might explain clinical effects. [8] This is a proposed mechanism, not a proven one.| Question | What the source found | Strength of evidence |
|---|---|---|
| Safety over three months | A randomized, placebo-controlled trial of 37 healthy adults compared two daily amounts of a standardized extract with placebo. It was well tolerated, and no efficacy outcomes were measured. [9] | Promising but limited (safety only) |
| Brain response to threat | A crossover study of 16 healthy volunteers found reduced amygdala reactivity to fearful faces after a single dose. [10] | Promising but limited (brain imaging, not symptoms) |
| Laboratory-induced anxiety | Two small placebo-controlled studies in 20 healthy volunteers: no treatment effect in the first, lower reported anxiety before the stress task in the second. The authors called the evidence tentative. [11] | Insufficient evidence |
| Anxiety or depression as illnesses | A 2021 review said the plant had not yet been studied in a clinical population. [6] | Insufficient evidence |
Sellers sometimes describe kanna as a natural antidepressant. Those are marketing claims; the trials above did not test people with depression or anxiety disorders.
Related pages
African traditional medicine overview, African potato, traditional herbs and prescription medicines and talking with a health professional.Frequently asked questions
Is Sutherlandia proven to treat cancer or HIV?
No. It has a long traditional reputation as a tonic, but a 2005 review found no clinical trials of efficacy for HIV, and a 24-week trial in adults with HIV showed no change in viral load or CD4 count. [5][3]
Is Sutherlandia safe to take with HIV medicines?
That is not established. Lab work shows it can affect enzymes and transporters that handle antiretroviral drugs, and a small study in 12 healthy men found lower blood levels of the HIV medicine atazanavir after Sutherlandia, and a trial raised a possible interaction with tuberculosis prevention medicine. Ask your HIV clinician or pharmacist first. [4][14][3]
Can kanna replace my antidepressant?
No. Trials have not tested kanna in people with depression or anxiety disorders, and the two may overlap in how they act on serotonin. Do not stop or change a prescribed medicine without your prescriber. [6][8][12]
Who traditionally used kanna?
Reviews describe use by the San and Khoikhoi peoples of southern Africa. [7][6] Some uses were social or spiritual, and this site does not describe them.
Is kanna legal?
It depends on the country and the product. Kanna is on a UN "plants of concern" list, and regulation is described as challenging, so check the rules where you live and talk with a pharmacist. [13]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Medicine interactions and other cautions
- Antidepressants (SSRIs). SSRIs are selective serotonin reuptake inhibitors, the most widely used type of antidepressant. [12] Because the kanna extract also blocks the serotonin transporter in lab tests [8], the two may overlap. We found no study testing kanna together with an SSRI, so the size of any risk is unknown. Anyone taking an antidepressant should ask a prescriber or pharmacist before using kanna. The NHS notes that antidepressants can cause problems with some other medicines, including the herbal remedy St John's wort. [12]
- Product variation. In one analysis of six commercial kanna products, the amount of one active compound (hordenine) ranged from about 0.03 to 1.07 mg per gram of plant material. [13] Kanna is also on a United Nations Office on Drugs and Crime list of "plants of concern", and the authors say regulation is challenging. [13] Rules differ by country, so check your own.
- Pregnancy, breastfeeding and children: proper evidence not found for Sutherlandia or kanna in these groups. See traditional medicines in pregnancy and childhood.
- Mental health. Anxiety or low mood that lasts, or any thought of self-harm, needs a clinician. In the United States, call or text 988 for crisis support, or call 911 in an emergency. Never stop a prescribed medicine to try a plant remedy.
References
- A review of the taxonomy, ethnobotany, chemistry and pharmacology of Sutherlandia frutescens. J Ethnopharmacol 2008. Read 2026-10-22.
- A randomized, double-blind, placebo-controlled trial of Lessertia frutescens in healthy adults. PLoS Clin Trials 2007. Read 2026-10-22.
- Consumption of Sutherlandia frutescens by HIV-Seropositive South African Adults: An Adaptive Double-Blind Randomized Placebo Controlled Trial. PLoS One 2015. Read 2026-10-22.
- Impact of African herbal medicines on antiretroviral metabolism. AIDS 2005. Read 2026-10-22.
- African herbal medicines in the treatment of HIV: Hypoxis and Sutherlandia. An overview of evidence and pharmacology. Nutr J 2005. Read 2026-10-22.
- Sceletium tortuosum: A review on its phytochemistry, pharmacokinetics, biological and clinical activities. J Ethnopharmacol 2021. Read 2026-10-22.
- A Chewable Cure "Kanna": Biological and Pharmaceutical Properties of Sceletium tortuosum. Molecules 2021. Read 2026-10-22.
- Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids. J Ethnopharmacol 2011. Read 2026-10-22.
- A randomized, double-blind, parallel-group, placebo-controlled trial of Extract Sceletium tortuosum in healthy adults. J Altern Complement Med 2013. Read 2026-10-22.
- Acute effects of Sceletium tortuosum (Zembrin), a dual 5-HT reuptake and PDE4 inhibitor, in the human amygdala. Neuropsychopharmacology 2013. Read 2026-10-22.
- Sceletium tortuosum ameliorates experimentally induced anxiety in healthy volunteers. Hum Psychopharmacol 2020. Read 2026-10-22.
- NHS: Antidepressants. Read 2026-10-22.
- Quantification of hordenine in a complex plant matrix... Application to the 'plant of concern' Sceletium tortuosum. Drug Test Anal 2022. Read 2026-10-22.
- Müller AC, Skinner MF, Kanfer I. Effect of the African Traditional Medicine, Sutherlandia frutescens, on the Bioavailability of the Antiretroviral Protease Inhibitor, Atazanavir. Evid Based Complement Alternat Med 2013. Abstract read via Europe PMC 2026-10-24.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.