Who Should Not Take Kanna?
For several groups the research is silent, and silence is a reason to ask a clinician before trying it, not a green light.
Who should not take kanna? The honest answer is not a tidy list of banned conditions. It is a set of groups where the safety research either does not exist or points to caution, so the right first step is a conversation with a doctor or pharmacist. This post goes through each group, says what the sources actually state, and shows who the human trials left out. It is a companion to is kanna safe?
People who are pregnant or breastfeeding, take antidepressants or other serotonin-affecting medicine, have liver or kidney problems, have a mental health condition, are having surgery, or are under the age limit on a product should ask a clinician before using kanna [1][6]. Human trials enrolled healthy adults [7], so for these groups the safety data are missing, which is not the same as safe.
Is kanna safe during pregnancy or breastfeeding?
No one can say it is, and the sensible default is to skip it unless a clinician tells you otherwise.
WebMD states: "It is not known if or how sceletium could affect pregnancy or harm a fetus," and it is not known if sceletium passes into breast milk [1]. The 2014 cognition trial, one of the few human studies we could read in full, listed pregnancy among its exclusion criteria [2]. So the people who were studied were not pregnant.
Unknown does not mean harmless, and it does not mean harmful. It means the question has not been answered. For a product with that gap, the cautious choice is to avoid it while pregnant or nursing, or to take the question to your obstetrician or midwife.
Should people on antidepressants or other medicines avoid it?
They should not self-experiment. They should talk to the prescriber or pharmacist first, and not stop any prescription to try kanna.
WebMD lists MAOIs (including those taken within the past two weeks), SSRIs, SNRIs, tricyclic antidepressants, antipsychotics, triptans and St. John's wort as medicines to discuss with a provider, and says the research on drug interactions is incomplete [1]. The reasoning is mechanistic: a standardized kanna extract blocked the serotonin transporter in lab tests [8], and MedlinePlus describes serotonin syndrome as a reaction that most often occurs when two or more serotonin-affecting medicines or drugs are combined [3]. We found no published case of kanna causing it and no human interaction study.
MedlinePlus is clear on one more point that matters here: do not stop taking your medicine, and talk to your health care provider about your concerns first [3]. The full explanation is in kanna and SSRIs, and a broader table is in kanna drug interactions.
What about mental health conditions, including bipolar disorder?
We found no research on kanna in people with bipolar disorder or other diagnosed conditions, so the answer is to ask the clinician who manages your care.
WebMD advises telling a provider about mental health conditions before using sceletium, and about any history of prescription or street drug misuse [1]. The human studies were in healthy volunteers. A 2021 review notes the plant has not yet been studied in a clinical population [9], and a 2026 critical review flags small samples and studies in clinically irrelevant populations [10]. The Chiu trial excluded people with active suicide risk and those whose Hamilton depression score was 8 or higher [2].
We are not saying kanna worsens any condition. We are saying the research cannot tell you either way, and that anyone with a serious mood condition has medical reasons to want a clinician in the loop. Nothing on this site suggests kanna for any condition.
What about liver, kidney or heart conditions?
WebMD lists kidney or liver problems among the conditions to tell a provider about, and the trials excluded several serious conditions.
- Liver and kidney. In a 3-month trial of 37 healthy adults, blood chemistry showed no significant changes [4]. We found no case report of liver injury attributed to kanna. But healthy participants say little about people whose livers or kidneys already struggle with processing substances. WebMD says to mention these problems to a provider [1].
- Heart and blood pressure. We found no trial reporting a cardiovascular problem. The 3-month trial found no apparent differences in vital signs or ECG [4]. However, the Chiu trial excluded uncontrolled hypertension, recent heart attack or unstable angina, among other conditions [2], so those groups are unstudied.
- Seizure disorders, diabetes and others. We found no source that addresses kanna in these groups. Ask your clinician.
See also kanna side effects for what the trials recorded.
What about before surgery?
Tell your surgical team and anesthesiologist about every supplement, kanna drinks included, and follow their instructions on timing.
The American Society of Anesthesiologists says supplements can cause problems around surgery because they may prolong the effects of anesthesia, increase bleeding risk, raise blood pressure, interfere with other medications or cause heart problems. It says that in some cases an anesthesiologist may recommend stopping supplements at least two weeks before a procedure [6]. The brochure does not name kanna, and we found no study of kanna and anesthesia. The advice is general, and it is the reason to disclose rather than assume.
Is kanna safe for children and teens?
We found no safety studies in anyone under 18. The trials we read enrolled adults: a 3-month study of healthy adults [4], a 3-week study with a mean age of 54.6 [2], and an 8-day study of 60 adults aged 20 to 35 [5].
Product age limits are set by each brand and retailer, not by clinical data. For a drink marketed to adults, we would use 21 as the cautious line, as noted in is kanna safe?. That is an editorial judgment, not a finding from research. For the legal side, see is kanna legal?
Who else should hold off?
- People allergic to sceletium or any ingredient in a product. WebMD says they should not use it, and to stop and get help right away for signs of a serious allergic reaction [1].
- People who drink alcohol heavily or plan to drink. WebMD says there is not enough research to know whether sceletium interacts with alcohol [1]. We recommend not combining them. See kanna and alcohol.
- Anyone who has had an unexplained reaction to a kanna product. WebMD notes that product content can vary with growing conditions, harvest timing and processing, and that some sceletium products have been found to contain other ingredients, such as ephedrine [1].
- People with a history of misuse of prescription or street drugs. WebMD lists this among the things to tell a provider [1]. If you are worried about substance use, SAMHSA's National Helpline is free, confidential and open 24/7: 1-800-662-4357.
Who did the trials leave out?
Almost everyone in a clinic. The trials were designed to test small questions in healthy people.
| Group | Evidence in the studies we read |
|---|---|
| Pregnant people | Excluded from the Chiu trial [2]. No data otherwise. |
| Breastfeeding | No data [1]. |
| People with active suicide risk or a Hamilton depression score of 8 or higher | Excluded from the Chiu trial [2]. |
| Uncontrolled hypertension, recent heart attack, unstable angina, kidney failure, hepatitis, cirrhosis, epilepsy, malignancy | Excluded from the Chiu trial [2]. |
| BMI above 30 | Excluded from the Chiu trial [2]. |
| Children and teens | No trial found. Adult samples only [2][4][5]. |
| People on antidepressants and other serotonin-affecting medicine | No interaction study found. |
| Long-term users | Longest controlled trial was 3 months [4]. |
The exclusion list is from one trial's full text [2]; other trials may have used different criteria that we could not read.
So "who should not take kanna" has a plain-language answer. If you fall in any row above, or you are not sure, ask a pharmacist or doctor before you buy. The label of a kanna drink, a supplement or a tincture does not replace that advice. Do not stop or change a prescribed medicine on your own.
This page is general information, not medical advice. These statements have not been evaluated by the FDA, and kanna products are not intended for any disease or health condition.
References
- WebMD. Sceletium: Uses, side effects, interactions. webmd.com
- Chiu S, et al. Proof-of-concept randomized controlled study of cognition effects of the proprietary extract Sceletium tortuosum (Zembrin) targeting phosphodiesterase-4 in cognitively healthy subjects. Evid Based Complement Alternat Med 2014;2014:682014. PubMed Central
- MedlinePlus. Serotonin syndrome. National Library of Medicine. medlineplus.gov
- Nell H, Siebert M, Chellan P, Gericke N. A randomized, double-blind, parallel-group, placebo-controlled trial of Extract Sceletium tortuosum (Zembrin) in healthy adults. J Altern Complement Med 2013;19(11):898-904. PubMed
- Hoffman JR, Markus I, Dubnov-Raz G, Gepner Y. Ergogenic effects of 8 days of Sceletium tortuosum supplementation on mood, visual tracking, and reaction in recreationally trained men and women. J Strength Cond Res 2020;34(9):2476-81. PubMed
- American Society of Anesthesiologists. Herbal and dietary supplements and anesthesia (patient brochure, 2020). asahq.org (PDF)
- Reay J, Wetherell MA, Morton E, Lillis J, Badmaev V. Sceletium tortuosum (Zembrin) ameliorates experimentally induced anxiety in healthy volunteers. Hum Psychopharmacol 2020;35(6):1-7. PubMed
- Harvey AL, et al. Pharmacological actions of the South African medicinal and functional food plant Sceletium tortuosum and its principal alkaloids. J Ethnopharmacol 2011;137(3):1124-9. PubMed
- Olatunji TL, et al. Sceletium tortuosum: a review on its phytochemistry, pharmacokinetics, biological and clinical activities. J Ethnopharmacol 2021;280:114476. PubMed
- de Jong M, et al. Mesembryanthemum tortuosum and Zembrin: mixed evidence from in vivo animal and clinical studies on their antidepressant and anxiolytic effects. Planta Med 2026;92(8):806-823. PubMed
Frequently asked questions
Can you take kanna while pregnant or breastfeeding?
Nobody knows. WebMD says it is not known if or how sceletium could affect pregnancy or harm a fetus, or whether it passes into breast milk [1]. The trial we reviewed in detail excluded pregnancy [2]. Avoid it unless your clinician says otherwise.
Should people on antidepressants avoid kanna?
They should talk to a prescriber or pharmacist before trying it. WebMD lists SSRIs, SNRIs, MAOIs and tricyclic antidepressants as medicines to discuss with a provider [1]. No study has tested kanna with them. Never stop a prescribed medicine on your own [3].
Is kanna safe for teenagers or children?
We found no safety studies in children or teens. The human trials we read enrolled adults [2][4][5]. Kanna products carry brand-set age limits, and we would not rely on them as a safety guarantee.
Should I stop kanna before surgery?
Tell your surgical and anesthesia team about it. The American Society of Anesthesiologists says some patients are advised to stop supplements at least two weeks before a procedure [6]. Follow your own team's instructions.
Is kanna okay with bipolar disorder or other mental health conditions?
We cannot say. WebMD advises telling a provider about mental health conditions before using sceletium [1], and the trials enrolled healthy volunteers [7]. Ask the clinician who manages your care.