Ashwagandha vs Rhodiola: Which Adaptogen Fits Your Stress?

Adaptogens are plant extracts defined by their ability to help the body resist a broad range of stressors without pushing physiology in a single direction. Of the dozens marketed under the label, two have accumulated enough controlled human trials to take seriously: ashwagandha (Withania somnifera) and rhodiola (Rhodiola rosea).

“Adaptogen” is one of the most overused words on a supplement shelf: a vague promise that a herb will help your body “adapt to stress,” applied to almost anything. Strip away the marketing, though, and two plants have earned a real place in the clinical literature: ashwagandha and rhodiola. They’re worth taking seriously, but not for the reasons the labels usually suggest. The most useful thing to know is that they pull in opposite directions. One tends to settle you; the other tends to lift you. Picking the right one starts not with the bottle but with naming the kind of stress you’re actually carrying.

What “adaptogen” actually means

The term comes from mid-20th-century Soviet research and has a specific definition: a substance that’s broadly non-toxic, that helps the body resist a wide range of stressors, and that has a normalising effect, nudging an over-stressed system down and an under-functioning one up, rather than pushing in a single direction. The proposed mechanism centres on the hypothalamic-pituitary-adrenal (HPA) axis, the feedback loop that governs your cortisol response to stress.

That’s a plausible biological story, not a magic one. Adaptogens are studied as consistent-use supplements that gently shift your stress physiology over weeks, not as something you take in a rough moment for an immediate effect. The trial populations also matter: almost all of this research is in “stressed but healthy adults,” not people with a diagnosed condition.

Ashwagandha: the calming adaptogen

Ashwagandha (Withania somnifera) has moved from Ayurvedic tradition into the clinical-trial literature more successfully than almost any other herb, and its research centres on calming stress: the wired, tense, can’t-switch-off kind.

The landmark 2012 trial by Chandrasekhar and colleagues gave 64 chronically stressed adults a standardised root extract (KSM-66) at twice-daily 300 mg doses for 60 days, and found significant reductions in perceived-stress scores and in serum cortisol versus placebo. A 2019 trial by Lopresti and colleagues, using a different concentrated extract (Shoden) at 240 mg a day in 60 stressed adults, similarly found a significant drop on the Hamilton Anxiety scale alongside changes in cortisol and DHEA-S. These named, standardised extracts (not generic root powder) are the products that produced the headline results.

When the trials are pooled, the picture is encouraging but not unanimous. A 2025 systematic review and meta-analysis (Bachour and colleagues, BJPsych Open) combined 15 studies and 873 participants and reported significant reductions in anxiety, perceived stress and cortisol after eight weeks of supplementation, while noting no measurable improvement in overall quality of life. That last detail is a useful reality check, and it isn’t the only one. A separate 2025 meta-analysis by Albalawi, looking specifically at the cortisol-versus-perceived-stress question across studies of roughly 488 people, found a clear, statistically significant drop in cortisol but no significant effect on perceived stress: a genuine disconnect between the biological marker and how people actually reported feeling.

The fair summary for ashwagandha is: a real, repeatedly-observed effect on the stress hormone cortisol, a generally positive but inconsistent effect on how stressed and anxious people feel, and a body of evidence that is moderate in quality rather than definitive. It’s the herb to reach for when stress shows up as tension, racing thoughts and trouble winding down at night, but not a reason to expect a transformation.

Rhodiola: the energizing adaptogen

Where ashwagandha tends to calm, rhodiola (Rhodiola rosea, or golden root) tends to lift. It grows wild in cold northern climates, and much of its research (a lot of it from Scandinavia and the former Soviet states) focuses on the opposite face of stress: exhaustion, brain fog and burnout, the running-on-empty feeling rather than the wired one.

The most-cited supportive trial is Olsson and colleagues’ 2009 study of the standardised SHR-5 extract: 60 people meeting diagnostic criteria for stress-related fatigue took 576 mg a day for 28 days, and the rhodiola group improved over placebo on a burnout scale and on tests of attention and concentration, with a blunted cortisol response to waking. Earlier SHR-5 work (including Darbinyan’s study of physicians working night shifts) pointed the same way, toward better mental performance under fatigue.

The whole literature is mixed, though. The most rigorous synthesis, a 2012 systematic review by Ishaque and colleagues, identified 11 controlled trials and concluded that the evidence is contradictory: only some studies showed a benefit, no two measured the same outcomes, and every included trial carried a high or unclear risk of bias, which made pooling the results impossible. An earlier systematic review by Hung, Perry and Ernst reached a similarly cautious verdict. A well-designed 2014 trial by Punja and colleagues, testing rhodiola in 48 nursing students working shifts, found the opposite of the hoped-for result: outcomes actually favoured the placebo group, though the authors urged caution in interpreting it.

Read together, rhodiola is best described as promising but genuinely under-proven: a plausible mechanism, a couple of decent positive trials in burnout and fatigue, and a research base too small and too uneven to be confident about. It’s a reasonable choice when your stress looks like depletion rather than agitation (take it in the morning, as it can feel mildly stimulating), but it sits at the more tentative end of “moderate” evidence, closer to ashwagandha’s poorer cousin than its equal.

How to tell which one fits your stress

Strip both herbs back to what their research actually targets, and the choice is mostly about naming your own stress. Wired stress (tension, a racing mind, trouble sleeping, tired but unable to switch off) points toward ashwagandha, which has the stronger anxiety- and cortisol-specific trial record; take it in the evening. Worn-out stress (fatigue, brain fog, low drive, burnout, running on empty) points toward rhodiola, whose research centres on mental stamina under load; take it in the morning so it doesn’t disturb sleep.

Neither is an acute fix, and neither replaces the basics (sleep, movement, daylight, and connection) that do the heavy lifting for mood and stress resilience. Think of them as one small, optional layer of support on top of that foundation.

A supportive role, not a treatment

This is research on stress and fatigue in otherwise-healthy adults, not on treating a mental-health condition. Neither ashwagandha nor rhodiola is a treatment for depression or an anxiety disorder, and nothing here should be read that way.

If low mood, persistent anxiety, or exhaustion is interfering with your daily life, the most important step isn’t choosing an adaptogen. Talk to a doctor or therapist who can help you build a real plan, which a supplement might support as one small part. If you need to talk to someone now, our Get help page lists free, confidential options, and our medical disclaimer explains the limits of general information like this.

Typical use

The trials that showed a signal share a few practical patterns. These are general observations from the literature, not a prescription. Your dose, and whether either herb is appropriate at all, is a conversation for a clinician, especially if you take other medication.

For ashwagandha, the extract is the active ingredient. The results came from named, standardised extracts: KSM-66 (root-only, standardised to at least 5% withanolides, typically 300–600 mg a day), Sensoril, or Shoden (more concentrated, effective at lower doses). Generic “ashwagandha root powder” with no named extract and no stated withanolide content is not what the trials tested. Our ashwagandha profile breaks down how to read a label.

For rhodiola, look for a standardised SHR-5-type extract (roughly 3% rosavins and 1% salidroside, the ratio used in the supportive trials) at around 200–400 mg, taken in the morning because of its mild stimulating effect. Our rhodiola rosea profile covers what to check for.

Give either one weeks, not days. Where benefits appeared, they built over roughly four to eight weeks of consistent daily use. A fair trial is at least six to eight weeks before you decide whether it’s doing anything for you. And match the herb to the stress rather than the other way around: calm for wired, lift for worn-out. The energising reputation of rhodiola in particular can mask the fact that it doesn’t replace rest.

What to look for in an adaptogen supplement for stress

Since the right adaptogen depends on the kind of stress you carry, the label reading is what makes or breaks a purchase. Match the herb to the stress first, then check four things. Look for a named, standardised extract rather than a generic root powder: KSM-66 or Sensoril for ashwagandha, an SHR-5-type extract for rhodiola, because those are what the trials used. Check the stated active percentage, at least 5% withanolides for ashwagandha, roughly 3% rosavins and 1% salidroside for rhodiola. Confirm the dose falls in the studied range, about 300 to 600 mg a day for ashwagandha and 200 to 400 mg for rhodiola. And favour third-party testing for identity and contaminants, which also lowers the rare liver-injury concern tied to poor-quality ashwagandha. Our ashwagandha profile and rhodiola rosea profile break down how to read each label, and the stress guide frames where adaptogens sit among other support.

Cautions and interactions

“Natural” doesn’t mean “no considerations,” and the two herbs have quite different caution profiles.

Ashwagandha is not recommended during pregnancy. It can nudge thyroid hormone levels, so use caution if you have a thyroid condition or take thyroid medication, and check with your doctor first. If you take sedatives or immunosuppressant medication, discuss it with a clinician before starting. Rare cases of liver injury have been reported, which is another reason to buy reputable, third-party-tested brands rather than the cheapest powder.

Rhodiola can feel stimulating, so take it earlier in the day to avoid disrupting sleep. Talk to your doctor before combining it with antidepressants or stimulants, or if you have bipolar disorder because of its activating effect.

Combining the two herbs, or either with other supplements, is worth raising with a clinician rather than improvising, particularly alongside any medication that affects mood or sleep, or if you’re breastfeeding or managing an existing health condition.

The bottom line

Ashwagandha and rhodiola are the two adaptogens with enough research behind them to take seriously, but “enough to take seriously” is not the same as “proven.” Ashwagandha has the stronger and more consistent record, reliably lowering cortisol and, less consistently, easing how stressed and anxious people feel; it suits the wired kind of stress. Rhodiola is more tentative: a couple of supportive burnout trials set against contradictory reviews and at least one null result. It suits the worn-out, depleted kind. For both, the standardised extract matters more than the milligram count on the front of the bottle, and the most useful first step is matching the herb to the stress you actually have.

For more detail, see our full profiles of ashwagandha and rhodiola rosea, or browse the journal for more on mood, stress and sleep support.

Supplements mentioned

• Ashwagandha (KSM-66 / Sensoril): our profile of the calming adaptogen, with evidence tier, how to choose a standardised extract, typical use and cautions.
• Rhodiola Rosea: our profile of the energizing adaptogen for fatigue and burnout, with dosing and cautions.

Sources

1. Chandrasekhar K, Kapoor J, Anishetty S. A prospective, randomized double-blind, placebo-controlled study of safety and efficacy of a high-concentration full-spectrum extract of ashwagandha root in reducing stress and anxiety in adults. Indian Journal of Psychological Medicine. 2012;34(3):255–262. doi:10.4103/0253-7176.106022. https://pmc.ncbi.nlm.nih.gov/articles/PMC3573577/
2. Lopresti AL, Smith SJ, Malvi H, Kodgule R. An investigation into the stress-relieving and pharmacological actions of an ashwagandha (Withania somnifera) extract: a randomized, double-blind, placebo-controlled study. Medicine (Baltimore). 2019;98(37):e17186. doi:10.1097/MD.0000000000017186. https://pubmed.ncbi.nlm.nih.gov/31517876/
3. Bachour G, Samir A, Haddad S, Houssaini MA, El Radad M. Effects of ashwagandha supplements on cortisol, stress, and anxiety levels in adults: a systematic review and meta-analysis. BJPsych Open. 2025;11(S1):S39. doi:10.1192/bjo.2025.10136. https://www.cambridge.org/core/journals/bjpsych-open/article/effects-of-ashwagandha-supplements-on-cortisol-stress-and-anxiety-levels-in-adults-a-systematic-review-and-metaanalysis/6F2D7847C1F64707F2034A45FD6CF0C0
4. Albalawi AA. Dual impact of ashwagandha: significant cortisol reduction but no effects on perceived stress — a systematic review and meta-analysis. Nutrition and Health. 2025;31(4):1395–1408. doi:10.1177/02601060251363647. https://journals.sagepub.com/doi/10.1177/02601060251363647
5. Olsson EM, von Schéele B, Panossian AG. A randomised, double-blind, placebo-controlled, parallel-group study of the standardised extract SHR-5 of the roots of Rhodiola rosea in the treatment of subjects with stress-related fatigue. Planta Medica. 2009;75(2):105–112. doi:10.1055/s-0028-1088346. https://pubmed.ncbi.nlm.nih.gov/19016404/
6. Ishaque S, Shamseer L, Bukutu C, Vohra S. Rhodiola rosea for physical and mental fatigue: a systematic review. BMC Complementary and Alternative Medicine. 2012;12:70. doi:10.1186/1472-6882-12-70. https://pmc.ncbi.nlm.nih.gov/articles/PMC3541197/
7. Hung SK, Perry R, Ernst E. The effectiveness and efficacy of Rhodiola rosea L.: a systematic review of randomized clinical trials. Phytomedicine. 2011;18(4):235–244. doi:10.1016/j.phymed.2010.08.014. https://pubmed.ncbi.nlm.nih.gov/21036578/
8. Punja S, Shamseer L, Olson K, Vohra S. Rhodiola rosea for mental and physical fatigue in nursing students: a randomized controlled trial. PLoS ONE. 2014;9(9):e108416. doi:10.1371/journal.pone.0108416. https://pmc.ncbi.nlm.nih.gov/articles/PMC4182456/

A note from us: adaptogens can play a small supporting role in how you handle everyday stress, but they are not a treatment for depression, anxiety, or burnout as a clinical condition. If stress or low mood is interfering with your life, a doctor or therapist is the right first step. If you need support now, our Get help page lists free, confidential options.