Rhodiola rosea

Below are our grades for mental fatigue, perceived stress and endurance. Our how we grade evidence page explains each grade, and the evidence matrix compares compounds.

Two systematic reviews set the scene. A 2011 review of 11 placebo-controlled randomized controlled trials found that rhodiola may have beneficial effects on physical and mental performance, but noted a lack of independent replication of the individual studies [2]. Only 5 of the 10 trials it scored reached more than three points on the Jadad quality score [2]. The US National Center for Complementary and Integrative Health (NCCIH) says most of the research in people is of low-to-moderate quality [26].

Does rhodiola reduce mental fatigue?

Evidence is mixed: older trials of one extract reported less mental fatigue [3][4][5], while a later registered trial found the opposite [6]. A 2012 systematic review included 11 controlled trials and found that three of five randomized trials of mental fatigue reported a benefit [1]. The same review found that every included study had a high risk of bias or reporting flaws that made its validity hard to judge, and it called the research contradictory [1]. For context, see our hub on mental energy and fatigue.

The positive trials all tested the SHR-5 extract against placebo. In a double-blind crossover trial in 56 young, healthy physicians on night duty, scores on mental fatigue tests improved with one tablet a day, with a statistically significant improvement reported during the first two-week period [3]. In a small randomized, double-blind pilot trial, foreign students in an examination period took the extract or placebo for 20 days; the most significant improvements were in physical fitness, mental fatigue and neuro-motor tests, and the authors thought the dose was probably too low [4]. In 161 military cadets aged 19 to 21, a single dose raised an anti-fatigue index compared with placebo, with no significant difference between the two doses tested [5].

These three trials share a co-author and use the same extract [3][4][5], and the 2011 review flagged the lack of independent replication [2]. Their funding is not stated in the PubMed records we checked.

The main counterweight is a registered trial (NCT01278992) from a different research group, funded by the Government of Alberta through AVAC Ltd. [6]. Forty-eight nursing students on shift work took 364 mg of rhodiola or an identical placebo daily for 42 days [6]. Fatigue worsened with rhodiola compared with placebo on both fatigue measures, though the authors advise caution in reading the result [6].

Two further studies were in people with a diagnosed fatigue syndrome or long-lasting fatigue symptoms, and results may not apply to healthy adults. In a randomized, double-blind trial of 60 adults meeting Swedish diagnostic criteria for fatigue syndrome (a clinical population), both groups improved, showing a placebo effect, but 576 mg a day of SHR-5 for 28 days improved a burnout scale and some attention measures more than placebo [7]. An uncontrolled, open-label study of 100 adults with prolonged or chronic fatigue, who took 2 x 200 mg of WS 1375 for 8 weeks, reported the greatest change after 1 week; the authors describe the analysis as exploratory and meant to generate hypotheses [10].

Does rhodiola lower perceived stress?

The evidence is thin and lacks placebo controls. As of November 11, 2026 we found no placebo-controlled trial of rhodiola alone that measured perceived stress in healthy adults (PubMed and Europe PMC search, November 11, 2026). For related compounds, see our hub on mood and stress.

In a trial funded by Dr Willmar Schwabe GmbH & Co. KG, 80 mildly anxious adults were randomized to 2 x 200 mg a day of the branded product Vitano or to no treatment [8]. The rhodiola group reported less stress and better total mood than the untreated controls at 14 days, with no relevant difference in cognitive test performance [8]. The authors note that it was not placebo-controlled and say they cannot determine a causal relationship [8].

A single-arm, open-label study gave 200 mg of WS 1375 twice daily for 4 weeks to 101 adults with life-stress symptoms [9]. Every questionnaire, including the Perceived Stress Questionnaire, improved, but the study had no comparison group [9]. Its funding is not stated in the PubMed record.

EMA's herbal committee also considered small placebo-controlled studies in adults with stress and fatigue. It observed a possible effect but identified several shortcomings in them, so its conclusions rest on long-standing use instead [22].

Does rhodiola improve endurance?

Evidence is mixed, and the two most recent meta-analyses disagree [11][12]. A 2025 meta-analysis of 26 randomized controlled trials in 668 healthy participants (mean age 22.0) found rhodiola improved VO2max, the body's maximum oxygen uptake (11 studies; effect size, a standardized measure of the difference between groups, 0.32), time to exhaustion (7 studies; 0.38) and time-trial performance (5 studies; -0.40), all small effects compared with placebo or control [11]. Its authors say differences between studies (heterogeneity) warrant cautious interpretation, and some variability persisted after subgroup analyses [11]. VO2max improved more at doses above 600 mg a day in a subgroup analysis [11].

A 2026 meta-analysis of 9 randomized trials (424 healthy adults) found no significant effect on VO2max (95% CI: -0.91 to 2.99; P=0.30) [12]. It pooled several Rhodiola species, including Rhodiola crenulata, and its authors attribute the uncertainty to differences in study design, sample size, dosing and duration [12]. A 2023 systematic review of 13 trials (263 participants) concluded that single doses helped endurance and perceived exertion, while repeated daily use helped anaerobic performance but not endurance, and most included studies had unclear or high risk of bias [13]. See our physical performance hub for other compounds.

Individual trials show the same split. In a randomized, double-blind crossover trial in 24 young healthy volunteers, 200 mg of extract taken 1 hour before testing extended time to exhaustion from 16.8 to 17.2 minutes compared with placebo, but in a 12-person 4-week phase, daily use changed none of the measures [14]. In a double-blind crossover trial in 18 adults, 3 mg/kg taken 1 hour before a 6-mile cycling time trial produced a finish of 25.4 minutes against 25.8 minutes with a carbohydrate placebo, with lower perceived exertion [15]. In contrast, in a randomized trial in 12 resistance-trained men, 1500 mg a day for 4 days produced no significant difference in time to exhaustion [16], and in a double-blind trial in 26 physically active male students, 600 mg a day for 4 weeks did not change endurance capacity, though it shortened reaction time [17].

What the evidence does not show

NCCIH concludes that there isn't enough reliable evidence to determine whether rhodiola is useful for any health-related purpose [26]. Participants in the 2025 endurance meta-analysis had a mean age of 22.0 [11], and men outnumbered women in the 2023 review by 198 to 65 [13], so results may not transfer to women or older adults.

As of November 11, 2026 we found no human pharmacokinetic studies reporting the half-life of rhodiola constituents (PubMed and Europe PMC search, November 11, 2026), so this page cannot report a half-life. In the single-dose endurance trials, participants took the extract 1 hour before testing [14][15]. A systematic review found effects on endurance after single doses but not after repeated daily use [13].

EMA's monograph covers a dry extract made with 67-70% ethanol [21]. In the UK, registered products include capsules with 153 mg of extract and tablets with 200 mg of the WS 1375 extract [24]. Health Canada requires the label direction "Avoid taking before bedtime" on products made under its monograph [23].

A 2011 systematic review of randomized trials found only a few mild adverse events [2], and a 2025 meta-analysis of 26 endurance trials found none reported, though it notes that underreporting cannot be ruled out [11]. In the 42-day nursing trial, the total number of adverse events did not differ between rhodiola and placebo [6]. No serious side effects attributable to the extract were reported in the fatigue syndrome trial [7], and adverse events in the 101-person open-label study were mostly mild, with none serious [9].

EMA lists headache, nausea, abdominal pain, diarrhea, skin rash and itching as undesirable effects, with frequency not known [21]. NCCIH says rhodiola is possibly safe for up to 12 weeks, with side effects that may include dizziness, headache, insomnia, and dry mouth or excessive saliva [26], and Memorial Sloan Kettering lists dizziness and dry mouth [27]. Health Canada requires products under its monograph to tell users: "Stop use if you experience irritability or insomnia" [23].

Some safety data are missing. EMA notes that tests on reproductive toxicity, genotoxicity and carcinogenicity are not available, that no studies have looked at driving and using machines, and that no case of overdose has been reported [21].

The clearest human data concern one liver enzyme. In a randomized crossover study, 13 healthy volunteers took a probe cocktail of medicines with and without 14 days of a commercial rhodiola product (Arctic Root, made by the Swedish Herbal Institute) [18]. Rhodiola lowered the losartan metabolite ratio by 21%, a sign of reduced CYP2C9 activity, and had no significant effect on the other enzymes tested, including CYP3A4 [18]. The authors call the effect modest but say it might be clinically relevant for CYP2C9 drugs with a narrow therapeutic index, such as phenytoin and warfarin [18]. NCCIH reports interactions with losartan [26], and Memorial Sloan Kettering advises people taking warfarin to talk to their healthcare provider [27].

In laboratory (in vitro) tests, rhodiola extracts were potent inhibitors of the enzyme CYP3A4 and the drug transporter P-glycoprotein [19]. Memorial Sloan Kettering says the clinical relevance of the CYP3A4 finding is yet to be determined [27].

Health Canada's monograph requires labels to tell people to ask a health care practitioner before use if they take antidepressant medication, hormone replacement therapy or birth control medication [23]. Memorial Sloan Kettering cites a case report of a fast, irregular heartbeat when rhodiola was taken with an antidepressant [27]. EMA's monograph, by contrast, states that no clinically relevant interactions have been observed [21]. As of November 11, 2026, we had not checked the Natural Medicines, LiverTox or DrugBank interaction entries.

If you take any of these medicines, talk to your doctor or pharmacist before combining them with rhodiola.