Adaptogens for Beginners: Ashwagandha and Rhodiola, Complete Guide 2026

In 2023, Denmark banned ashwagandha in dietary supplements, and in the European Union, a procedure under Article 8 of Regulation 1925/2006 is underway regarding this raw material, which may result in a similar ban across the entire market (Brendler et al., 2026). This is an inconvenient but honest start to a guide on adaptogens. These plants have real pharmacology and thus real risks. Ashwagandha and rhodiola are added to carts more often than any other anti-stress herb, usually without reading anything beyond the package description. Below you will find what can be said about them based on human studies: what doses were tested, how small the trials were, what we still don’t know, and who should definitely avoid these herbs.

KEY INFORMATION
• A series of 23 cases from Indian centers describes liver injury after ashwagandha. Three patients with pre-existing liver disease died (Philips et al., Hepatology Communications 2023).
• Ashwagandha: tested doses were 240-600 mg standardized extract, trials lasted from 30 to 112 days. Rhodiola: 400-576 mg for 4 weeks.
• Ashwagandha lowers TSH and raises T3 and T4, so it is risky in hyperthyroidism and when taking levothyroxine.
• Do not use during pregnancy or breastfeeding. Denmark withdrew ashwagandha from supplements in 2023.
• Clinical trials of both herbs are small, from 50 to 101 participants, and the tested extract is sometimes supplied or funded by its manufacturer.

What is an adaptogen and how is it different from coffee?

An adaptogen is a plant that is supposed to increase the body’s resistance to stress nonspecifically, i.e., regardless of the stressor. The criteria by which it is recognized were formulated in 1969 by Soviet pharmacologists Israel Brekhman and Igor Dardymov, setting three conditions: nonspecific action, normalization of physiology in both directions, and lack of significant toxicity (Brekhman and Dardymov, Annual Review of Pharmacology, 1969).

The difference from coffee lies in the direction of action. Caffeine always stimulates the sympathetic nervous system, regardless of whether the body needs it. An adaptogen is supposed to boost performance when it is lacking and calm down when stimulation is too high. This sounds suspiciously convenient and indeed it is difficult to measure such bidirectionality in a single study.

Pharmacologically, this involves the hypothalamic-pituitary-adrenal axis. Panossian argued that adaptogen actions cannot be described by a classic single receptor model because their molecular targets and signaling pathways are linked simultaneously to stress hormones and homeostasis regulators (Panossian, Annals of the New York Academy of Sciences, 2017). A 2021 review by the same team traced the concept from tradition to conventional medicine, described a biphasic response (small doses act as a mild stressor triggering adaptive pathways), and stated plainly that the potential of adaptogens remains poorly studied (Panossian et al., Medicinal Research Reviews, 2021).

It is worth remembering where the term came from. Brekhman worked for the Soviet pharmaceutical industry on preparations for athletes, soldiers, and shift workers, and his first works concerned eleuthero. The criteria were thus written for a specific practical purpose, not to define a pharmacological class in today’s sense.

The practical conclusion is that “adaptogen” is neither a legal nor medical category. It does not mean tested, does not mean safe, and says nothing about dose. It only indicates the tradition to which the plant belongs. A manufacturer who places this word on the label does not have to prove anything beyond that the raw material may be added to food.

Which adaptogen has what evidence and for what?

Eight plants and fungi are sold in Poland as adaptogens, but the state of evidence in humans varies greatly among them. Ashwagandha and rhodiola have about a dozen randomized trials each, while schisandra and eleuthero have practically only preclinical studies. The table below summarizes doses actually tested in clinical trials.

Note the row with ginseng. A 2010 Cochrane review included nine randomized trials, only five of which could be analyzed, and data could not be pooled due to differences in doses and measurements. The authors concluded there is no convincing evidence for cognitive improvement in healthy people (Geng et al., Cochrane 2010). This illustrates how far popularity can outpace data. More about fungi can be found in the post on adaptogenic mushrooms.

What have studies really shown about ashwagandha?

Two randomized trials form the core of the rest. Chandrasekhar et al. gave 64 people under chronic stress 300 mg extract twice daily for 60 days and achieved a significant reduction in all stress scales versus placebo and lowered serum cortisol (Chandrasekhar et al., 2012).

The second is Lopresti et al.: 60 adults, 240 mg standardized Shoden extract once daily for 60 days, double-blind. The ashwagandha group had a significantly greater reduction in anxiety on the HAM-A scale and morning cortisol and DHEA sulfate than placebo (Lopresti et al., 2019). The often-cited “23% cortisol reduction” is true but describes within-group change over time in the ashwagandha group, with a 0.5% increase in placebo, not the between-group difference. The between-group comparison was also significant, so the number may be cited if context is given.

A 2023 systematic review collected nine clinical trials measuring cortisol in stressed individuals. Supplementation lowered secretion without serious adverse effects, but the authors noted three things: studies differed in preparation and dose, lasted 30 to 112 days, and none checked what longer cortisol reduction does to adrenal function (Della Porta et al., 2023).

Separate are animal and cell culture studies, of which there are hundreds for ashwagandha. They describe withanolides’ effects on cancer, neurodegeneration, and inflammation, usually at concentrations unattainable by swallowing a capsule. These explain mechanisms but say nothing about what happens to a human taking 600 mg extract daily. Store descriptions mix both evidence levels, citing a mouse alongside anxiety scales.

Another point producers don’t mention but is visible in funding sections: the extract used by Chandrasekhar was supplied by Ixoreal Biomed, owner of the KSM-66 brand, and Lopresti’s study was funded by Arjuna Natural, which also supplied the tested Shoden preparation. This does not invalidate results but suggests treating them as signals, not conclusive evidence, especially in trials with about sixty participants.

What dose of ashwagandha and how soon does it work?

Tested doses in humans range from 240 to 600 mg standardized extract daily, given once or twice with meals. Below 240 mg there are no data, and above 600 mg almost none. Final measurements in the described trials were after 8 weeks or later, so assessment after one week is unsupported.

Three trade names of extracts exist on the market. KSM-66, used in Chandrasekhar’s study, is described as an extract obtained exclusively from root, without leaves, standardized by HPLC to at least 5% withanolides. Sensoril is made from root and leaf, i.e., a different raw material. Shoden, used in Lopresti’s study at 240 mg, is standardized to not less than 35% glycosylated withanolides. No study compares these three extracts head-to-head in the same people, so repeated store claims that one “calms better” and another “supports performance better” lack data support.

The best-documented effect concerns sleep. Langade et al. assigned 60 people with insomnia in a 2:1 ratio: forty received 300 mg extract twice daily for 10 weeks, twenty placebo. Sleep was measured by actigraphy. Sleep onset latency was 29.0 minutes versus 33.9 minutes in placebo, and sleep efficiency increased from 75.6 to 83.5% versus 75.1 to 79.7% in placebo (Langade et al., 2019). This is a real but modest improvement: about five minutes faster falling asleep.

Timing should be adjusted to your response. Ashwagandha can be sedative, so for some it works better in the evening, an hour before sleep. If you feel drowsy after a morning dose, move it to evening before deeming the preparation ineffective. Producers recommend taking with food, as withanolides absorb better with fat, though human studies comparing absorption fasting versus fed are practically absent. Practical dosing details are discussed separately in the post on ashwagandha for sleep and stress.

Can ashwagandha damage the liver?

Yes, and this is the most serious documented problem of this plant. Philips et al. collected 23 cases of drug-induced liver injury after ashwagandha from Indian centers from 2019-2022, including eight after single-ingredient preparations. Five patients had pre-existing chronic liver disease, three developed acute liver failure on that basis, and all three died (Philips et al., Hepatology Communications 2023).

The key detail is that chemical analysis of seized preparations showed no adulteration or contamination. Only natural plant compounds were found. Liver injury was caused by ashwagandha itself, not by an additive, which is often cited in similar reports.

The clinical picture is most often hepatitis with cholestasis. Biopsies showed features of bile stasis with hepatocyte necrosis and inflammatory infiltrate. In most patients without prior liver disease, injury was prolonged but self-limiting. One patient progressed to chronic form. A 2026 review points to transformation of withanolides by cytochrome P450 enzymes into reactive metabolites as a probable mechanism and lists besides hepatotoxicity also thyrotoxicosis and adrenal suppression (Kumar et al., 2026).

Proportions matter. Millions take ashwagandha, and only dozens of cases are described, so risk for a healthy liver remains low. The problem is that no one knows its scale: drug-induced liver injury is rarely reported, and supplements even less so, as patients often omit them in history. Reports came independently from three sources: an earlier series described cases from Iceland and the US drug-induced liver injury network (Björnsson et al., 2020), and the Indian one comes from a completely different market and producers. This argues against a single faulty batch theory.

Practically, if you have fatty liver, past viral hepatitis, cirrhosis, or take hepatotoxic drugs, ashwagandha is not for you. Signals to stop the preparation and see a doctor include yellowing of skin or eyes, dark urine, pale stool, persistent itching, and pain under the right rib cage.

What does ashwagandha do to the thyroid and why is it discouraged in pregnancy?

Ashwagandha shifts thyroid hormones toward hyperthyroidism. In an eight-week randomized trial with 50 people with subclinical hypothyroidism, 600 mg daily lowered TSH and raised T3 and T4 significantly versus placebo (Sharma et al., 2018). For this group, this is a beneficial effect. For others, it can be problematic.

A review of ashwagandha’s effects on the endocrine system describes the same direction: increased T3 and T4 secretion by the thyroid and subsequent TSH decrease via the hypothalamic-pituitary-thyroid axis (Wiciński et al., 2023). If you have Graves’ disease, toxic nodular goiter, or take levothyroxine, this means a risk of hormone overdose without changing the drug dose. TSH control after 6-8 weeks from start is a minimum, and consulting an endocrinologist before starting is wiser.

Pregnancy is different from what most guides repeat. Ashwagandha has an Ayurvedic reputation as an abortifacient, and regulators warn based on that. A 2026 systematic review traced the citation chain and found the original sources weak, and animal studies showed no significant reproductive toxicity at doses corresponding to human consumption. The authors summarized the evidence as inconclusive (Tallon et al., 2026).

Inconclusive is not the same as safe. No trials involve or will involve pregnant women, so the recommendation remains simple: do not use ashwagandha during pregnancy or breastfeeding. Denmark’s 2023 decision to withdraw it from supplements was based on thyroid, sex hormones, and abortifacient reports.

Several other situations require caution. Ashwagandha enhances sedative and hypnotic drugs as it has sedative activity itself. It stimulates some immune responses, which theoretically conflicts with immunosuppressants after transplant and in autoimmune diseases. Rhodiola has isolated reports of stimulation and insomnia, and people with bipolar disorder should avoid it without psychiatrist approval. None of these interactions have been measured in randomized trials, so consulting your doctor replaces missing data.

How does rhodiola work and when is the effect seen?

Rhodiola (Rhodiola rosea) acts opposite to ashwagandha: instead of calming, it reduces mental fatigue. The best randomized trial included 60 people with fatigue syndrome who received 576 mg SHR-5 extract daily for 28 days. Compared to placebo, burnout scale scores and three attention indicators in the CCPT II test improved (Olsson et al., 2009).

This study is worth reading carefully because it shows how strong the placebo effect is here. Both groups improved on burnout, mental health, and MADRS depression scales. The difference favoring rhodiola appeared only in between-group comparisons and only in some measures. The authors also noted the extract blunted the morning cortisol surge upon awakening.

Measurements were taken on day 1 and day 28, so the widespread claim of “significant improvement from day 14” does not come from this work. Four weeks is the minimum period after which there is anything to assess.

Standardization matters more here than with ashwagandha. Studies used extracts standardized simultaneously for rosavins and salidroside, in proportions mimicking raw root. Products without stated percentages or standardized only for salidroside are not equivalent to what was studied.

Species also matter. Rhodiola crenulata and Rhodiola kirilowii, cheaper and chemically different, are sold. Rosavins occur practically only in Rhodiola rosea, so substitute species do not reproduce the study profile even if labeled “rhodiola.” The Latin name on the label settles this in two seconds. More about the plant is in the post on Rhodiola rosea.

Does rhodiola help with burnout and low mood?

The answer is: probably somewhat, but evidence is weaker than marketing suggests. Mao et al. compared rhodiola, sertraline, and placebo in 57 people with mild to moderate depression for 12 weeks. None of the between-group differences reached statistical significance (Mao et al., 2015).

Numbers were: HAM-D score drop of 8.2 points with sertraline, 5.1 with rhodiola, and 4.6 with placebo. The authors called their work a proof-of-concept study, not definitive. One clear and significant difference was adverse events: 63.2% on sertraline, 30.0% on rhodiola, and 16.7% on placebo. This is about twice fewer events than the drug, not 1.4 times fewer as popular versions claim.

Another often-cited study is Edwards et al. on WS 1375 extract. One hundred one people with life stress symptoms took 200 mg twice daily for four weeks, and all seven questionnaires showed improvement, partly after just three days (Edwards et al., 2012). The catch is it was an open, single-arm, non-randomized study. No one received placebo, so the extract effect cannot be separated from participation effect. The popular version cites a “28% burnout index drop,” but none of the tools used measured burnout.

The takeaway for readers is twofold. For mental fatigue in healthy people, rhodiola has the best data among adaptogens and an adverse effect profile comparable to placebo. For diagnosed depression, it does not replace treatment, and trying to substitute medication with an herb means many weeks without proven therapy. These are two different situations, often conflated in store descriptions.

How to distinguish a good extract from a shelf fake?

The deciding factor is the number on the package. Standardized extracts state the percentage of active substances. For ashwagandha, these are withanolides; for rhodiola, rosavins and salidroside. Lack of such a number means content is unknown, and the milligram dose then only indicates powder mass in the capsule.

The scale of the problem is measurable. Analysis of rhodiola products from the US market showed rosavin content from 0.01 to 3.08% and salidroside from 0.07 to 2.91%, a variation exceeding 300 times between products. Some deviated from label claims, one likely contained synthetic salidroside, and all seven tested capsules had trace amounts of arsenic, cobalt, and lead (Porwollik and Jafari, 2026).

For adaptogenic mushrooms, it depends on what the extract is made from. The fruiting body contains beta-glucans, while mycelium grown on grain contains mostly starch from the substrate. A label stating “fruit body” with polysaccharide content describes something different than one with “mycelium.”

An analytical certificate, or COA, is the third element. It confirms active substance content and absence of heavy metals and pesticide residues for a specific batch. Serious producers provide it upon giving the batch number. In Polish law, adaptogens are dietary supplements registered with the Chief Sanitary Inspectorate. Registration is not market approval after efficacy testing, and producers cannot claim treatment or disease prevention.

Price can be a hint, though unreliable. Producing a standardized root extract requires more raw material and a separate process than grinding it to powder, so a package declaring 5% withanolides at the cheapest powder price is a warning sign. The reverse is not true: high price alone confirms nothing, as no one has checked price versus label compliance. The deciding factor is the batch number document, not shelf position.

How to start to know if it works at all?

The biggest beginner mistake is starting with three preparations at once. In such a setup, you cannot tell what worked, what harmed, and what was mood fluctuation. The five steps below turn supplementation into a simple test with one variable.

The weakest link in such a trial is usually not the preparation but lack of a reference point. A person keeping a journal sees the difference or lack thereof in numbers after eight weeks. A person without a journal mostly remembers the last week. Breaks like “four weeks on, one week off” have no basis in studies, as no trial tested such a scheme, but a break gives a chance to check the state without the preparation.

Before buying anything, also check things that work stronger than any adaptogen combined. Regular sleep time, limiting afternoon caffeine, and daytime activity change morning cortisol more than 600 mg extract and cost nothing. A supplement added to a disrupted circadian rhythm usually has nothing to fix. If fatigue persists despite these changes, a sensible first step is blood count with ferritin and TSH rather than another capsule.

Summary: what to remember before the first package?

Ashwagandha and rhodiola are the two best-studied adaptogens, which in this group means about a dozen small randomized trials, usually funded by raw material producers. Effects are real but moderate. Five minutes faster falling asleep and a few points on burnout scales are not the same as promises in store descriptions.

On the risk side, the picture is clearer than on benefits. Ashwagandha damages the liver in some people, affects thyroid hormones, and has no place in pregnancy. Denmark withdrew it from supplements, and an EU procedure may repeat this. Rhodiola has a better safety profile, but product quality on the market is hit or miss.

It is also fair to name the knowledge state about the other six plants in the table. Ginseng has a Cochrane review ending with no convincing evidence, maca four trials deemed insufficient by reviewers, cordyceps one study with 28 people. The rest rely mainly on preclinical work. They are sold with as confident language as ashwagandha, despite a huge evidence gap.

If you still want to try, do it as an experiment: one herb, standardized extract at a dose from studies, a journal, and eight weeks of patience. And check beforehand if you belong to any groups for whom these plants are contraindicated.

Frequently Asked Questions

How long does it take to notice the effect of ashwagandha?

A review of nine trials reports durations from 30 to 112 days (Della Porta et al., 2023). The studies described here assessed effects after 8 weeks or later, and in the insomnia trial, sleep efficiency increased throughout 10 weeks. Assessment after one week is meaningless, as none lasted that short.

Is ashwagandha safe for the liver?

Not for everyone. A team from India described 23 cases of liver injury after ashwagandha from 2019-2022. Five patients had pre-existing liver disease, three developed acute liver failure on that basis, and all three died (Philips et al., 2023).

Does ashwagandha affect the thyroid?

Yes. In an eight-week trial with 50 people with subclinical hypothyroidism, a dose of 600 mg daily lowered TSH and raised T3 and T4 compared to placebo (Sharma et al., 2018). The same mechanism is problematic in hyperthyroidism and when taking levothyroxine.

Can adaptogens be taken during pregnancy?

No. Ashwagandha has a reputation in Ayurveda as an abortifacient, although a 2026 review considered these reports inconclusive and affected by citation distortion (Tallon et al., 2026). Inconclusiveness is not proof of safety, and no trials involve pregnant women.

Does rhodiola act faster than ashwagandha?

It appears so, although no direct comparison has been conducted. Rhodiola trials measured effects after 28 days, and an open 2012 study noted improvement after just three days (Edwards et al., 2012). Ashwagandha studies usually lasted 8 weeks or longer.

Can I combine ashwagandha with rhodiola?

There are no human studies on this combination, so the answer is based on pharmacology, not data. Rhodiola is taken in the morning as it can be stimulating, ashwagandha in the evening as it can be sedative. For beginners, it is wiser to test one herb at a time before considering combining.

How do I know if I’m buying an extract and not ground root?

By the number on the label. Standardized extracts state the percentage of withanolides or rosavins and salidroside. Analysis of seven rhodiola products from the US market showed rosavin content ranging from 0.01 to 3.08%, a 300-fold variation between products (Porwollik and Jafari, 2026).

If you are looking for standardized preparations with stated active substance content, browse the supplements category in our store and compare labels with the doses described above. For cortisol reduction alone, the post on supplements for stress and cortisol is also useful.

This article is for informational and educational purposes and does not replace consultation with a doctor. If you are pregnant, breastfeeding, taking medications, or have chronic conditions, consult a specialist before using supplements or herbs.

Author: Michał Waluk · Published: 2026-05-11 · Updated: 2026-08-11