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Adaptogens are considered plant-based and mild, but side effects can still occur, ranging from mild gastrointestinal discomfort to rare but serious reactions. Especially with ashwagandha, rhodiola, and ginseng, it is worth taking a look at the available studies, risk groups, and possible drug interactions before you start taking them.
- For ashwagandha, doses of less than 500 mg daily for up to three months are considered relatively safe, but doses of 600 mg or more over eight weeks have also been used in sleep studies.
- Since 2017, several case reports of liver damage caused by ashwagandha have been published, with symptoms appearing 2 to 12 weeks after starting treatment and usually subsiding within one to three months after discontinuation.
- Some authorities recommend using ginseng for no more than three months, as nervousness and, rarely, heart rhythm disorders can occur.
- If you are taking medication for blood sugar, blood pressure, or thyroid conditions, as well as anticoagulants, it is advisable to consult a doctor before taking ashwagandha, rhodiola, or ginseng.
Contents
- Overview of side effects by adaptogen
- Ashwagandha and the liver
- Who should be especially cautious
- Drug interactions
- Warning signs and the next step
- Conclusion: Consult a doctor instead of guessing
- Frequently asked questions
Which side effects have been documented for which adaptogen?
Gastrointestinal discomfort, fatigue, or restlessness are the most common side effects, and these are more of a nuisance than a danger. Serious side effects are rare, but when they occur, they are serious: liver damage caused by ashwagandha and interactions with medication.
| Adaptogen | Reported side effects | Doses and duration used in studies | How well documented? |
|---|---|---|---|
| Ashwagandha | Nausea, vomiting, diarrhea, drowsiness, headache, dizziness, sleepiness, skin rashes, and rarely liver damage (1) | For people without particular risk factors, doses of less than 500 mg daily for up to three months are considered relatively safe; doses of 600 mg or more over eight weeks have also been used in sleep studies (2) | Preliminary evidence: The side effects are based mainly on case reports, and comprehensive toxicological studies are lacking (2) |
| Rhodiola (rose root) | Lowers blood sugar and blood pressure (3) | Used for 12 weeks in a randomized study with 57 participants; rhodiola caused fewer adverse effects than the antidepressant sertraline (3) | Preliminary evidence: A few small studies |
| Ginseng (Panax ginseng) | Most commonly nervousness and irritability, and occasionally asthma attacks, high blood pressure, palpitations, heart rhythm disorders, and postmenopausal uterine bleeding (3) | Some authorities recommend using it for no more than three months (3) | Common side effects are well documented, but serious reactions have only been reported in individual cases |
| Cordyceps | If any, side effects are usually mild: diarrhea, constipation, and gastrointestinal discomfort | In a 48-week randomized study, there was no difference in the rate of side effects compared with a placebo | Unclear: there are almost no systematic human safety data, and most studies are small and short-term |
What about maca? There are no reliable human studies on the Andean tuber that have specifically investigated side effects, clear doses, and durations of use. This does not mean that maca is problematic. It only means that no one can reliably tell you how well tolerated it will be over many months.
One caveat applies to all the data: many safety statements are based on limited doses and durations. What worked well for eight weeks is not evidence that it will be safe for a year of continuous use.
Is ashwagandha harmful to the liver?
Liver damage caused by ashwagandha is rare but has been documented. Since 2017, several case reports have been published worldwide, including cases from Europe and Germany, including cases of acute liver failure (1).
In most cases, it was cholestatic or mixed hepatitis, identifiable by jaundice and itching. The symptoms appeared 2 to 12 weeks after starting treatment and usually subsided within one to three months after discontinuation.
In short: Cholestatic means that bile flow is impaired. Bile builds up, bile pigments enter the bloodstream, and this is exactly what causes yellowish skin, yellowish whites of the eyes, and itching.
In the controlled studies themselves, liver enzymes did not increase. Several products examined in the case reports were proven to contain pure ashwagandha without contamination, so contaminated powder is often ruled out as an explanation.
Why did the BfR still issue a warning? Because studies usually last only a few weeks and include only selected, healthy people. Rare reactions only become apparent when very large numbers of people take a substance. Furthermore, due to the lack of data, the authority could not establish a safe guideline for intake. That is why it also advises everyone without known risk factors to exercise caution (1).
If you want to learn more about ashwagandha and sleep, this article may be of interest: what is behind ashwagandha and sleep quality.
For whom are adaptogens (still) not a good choice?
For pregnant or breastfeeding women, children and adolescents, and people with liver, thyroid, or autoimmune diseases, adaptogens should not be used without medical supervision. The German Federal Institute for Risk Assessment explicitly stated this for ashwagandha in September 2024 (1); for other plants, the data are simply lacking.
| If this applies to you | Affected adaptogens | Why |
|---|---|---|
| Pregnancy or breastfeeding | Ashwagandha, cordyceps, and essentially all of them | The BfR expressly advises against ashwagandha (1); there is almost no safety data on cordyceps, so consult a doctor beforehand |
| Children and adolescents | Ashwagandha, cordyceps | The BfR and WHO advise against ashwagandha preparations (1) (2); data on cordyceps are lacking |
| Existing or previous liver disease | Ashwagandha | Case reports of liver damage; the BfR expressly advises against it (1) |
| Thyroid disease, especially with hormone therapy | Ashwagandha | Can affect thyroid function (1); consult a doctor before taking |
| Autoimmune diseases such as multiple sclerosis, lupus, or rheumatoid arthritis | Cordyceps | Can stimulate the immune system. The evidence is inconsistent, so a case-by-case decision with a doctor is necessary |
| Chronic illness or advanced age | Cordyceps | Due to the lack of safety data, a general recommendation to consult a doctor is given |
A word on Hashimoto: There is no controlled human study on ashwagandha for Hashimoto's thyroiditis. There is therefore neither evidence that it is harmful nor proof that it is safe over the long term. This gap is the reason why people with autoimmune thyroiditis or ongoing thyroid treatment are advised to exercise caution.
Which medications can adaptogens interact with?
Interactions with thyroid hormones, blood sugar and blood pressure medications, anticoagulants, immunosuppressants, antidepressants, and sedatives have been documented. Which plant is affected varies depending on the medication.
| If you take this | Affected adaptogen | What can happen | Recommended step |
|---|---|---|---|
| Thyroid hormones (e.g., levothyroxine) | Ashwagandha | In a placebo-controlled study, ashwagandha stimulated the body's own hormone production; combined with tablets, the hormone level can rise above the set target range | Consult a doctor beforehand and have your levels checked |
| Blood sugar medications | Ashwagandha (1), rhodiola (3) | Blood sugar can drop further, leading to hypoglycemia | Consult a doctor beforehand |
| Blood pressure medications | Ashwagandha (1), rhodiola (3) | Blood pressure can drop too low | Consult a doctor beforehand |
| Anticoagulants such as warfarin, as well as aspirin and nonsteroidal anti-inflammatory drugs | Rhodiola, ginseng (3) | Rhodiola can increase the concentration of warfarin (3). In a clinical study, the warfarin concentration dropped after two weeks of ginseng use, and the anticoagulant effect diminished | Do not combine without consulting a doctor |
| Immunosuppressants | Ashwagandha (1), rhodiola (3), cordyceps | The plants can counteract the medication's effect | Consult a doctor beforehand |
| Antidepressants | Rhodiola, ginseng (3) | Rhodiola with SSRIs: possible enhancement of effects. Ginseng: interactions with MAO inhibitors have been documented | Consult the treating practice beforehand |
| Sedatives (barbiturates) | Ashwagandha | The WHO warns of a possible enhancement of effects (2) | Consult a doctor beforehand |
| Corticosteroids, Digoxin, Hormone Replacement Therapy | Ginseng (3) | Interactions described | Consult your doctor beforehand |
Important: Your medications remain as prescribed. If anything needs to change, your doctor will decide, not the supplement. The pharmacy is also a quick point of contact, where interactions can be checked directly over the counter.
Good to know: Adaptogens are not only found in individual products. They are also often included in combination products (for example, CLAV's FOCUS contains 100 mg of ginseng extract per daily serving). If you take blood thinners, therefore check the ingredients list of every product.
How can you tell if your body is not reacting well to an adaptogen?
An important clue is the timing: symptoms that appear for the first time after you start taking it and were not there before. Stomach discomfort, nausea, unusual drowsiness in the morning, or more restless sleep are consistent with what has been reported for ashwagandha and other adaptogens (1).
In such a case, taking a break is the sensible first step. Stop taking the product and see for a few days whether the symptoms subside. If they do not improve or they return, you should see your family doctor.
Jaundice and itching are different. If your skin or the whites of your eyes turn yellowish, or if you experience itching for no apparent reason (especially within the first 2 to 12 weeks after starting), please seek medical advice promptly (2). Liver function can be quickly determined with a blood test.
And if you are wondering why it all sounds so vague: The studies on ashwagandha were primarily designed to find a benefit. Side effects were not systematically recorded, and different preparations, dosages, and combination products make it difficult to draw clear conclusions (1). Your own observations are therefore more valuable than they sound.
What CLAV products say about risk and origin
Every CLAV product states a recommended intake, which is intended as an upper limit: The stated daily amount should not be exceeded. The products are not recommended for children or pregnant women; further restrictions (for example for breastfeeding women or adolescents) are stated on the respective product page. CLAV itself notes that individual intolerances may occur in isolated cases. The products are manufactured in Germany, and all products are vegan.
Siberian ginseng, also known as taigawurzel, is botanically a different plant from the classic ginseng in the table above. At CLAV, it is contained in the capsule as pure root powder (900 mg per daily serving from two capsules, only powder and a plant-based capsule shell, from €17.90). If you take medication or have a pre-existing medical condition, the same rule applies here: consult your doctor first. Click here for the product.
You can find maca at CLAV in the STRONG complex with Black Maca and Tribulus, from €27.90. Because there are no targeted side-effect studies for maca, the information on the product page is particularly important here. Click here for the product.
If you want to know more about adaptogens in general, this article may be of interest to you: Basics of adaptogens and stress.
Sources
- German Federal Institute for Risk Assessment (BfR) (2024): Ashwagandha (sleep berry) preparations with possible health risks. Communication No. 039/2024. bfr.bund.de.
- Medical Tribune Switzerland: Ashwagandha: sleep-promoting adaptogen with rare risks. medical-tribune.ch.
- MSD Manual: Rhodiola (Professional Edition) and Ginseng (Patient Edition). Rhodiola · Ginseng.
The honest answer: Consult your doctor instead of guessing
The real problem is not that too little is known about adaptogens. Even the best study cannot reflect which tablets you take, which pre-existing medical condition you have, or what stage of life you are in. Your next step: Write down which medications and supplements you take and what symptoms you have noticed. Go through this list once with your doctor or at the pharmacy.
If you do not belong to any precaution group and tolerate your adaptogen well, you can rest easy. Pay attention to new symptoms, stick to the recommended intake, and take jaundice or itching seriously. That is all you need to make an informed decision.
FAQ: Frequently asked questions about the side effects of adaptogens
Can I simply stop taking ashwagandha, or do I need to taper off?
In most cases, you can simply stop. Tapering off is not required for ashwagandha as a dietary supplement. However, if you take thyroid, blood sugar, or blood pressure medications, inform your doctor. Your levels may shift after stopping.
Can taking it for weeks be harmful?
Rarely. In controlled studies, liver function tests remained unremarkable, and severe reactions are isolated cases. If the question keeps bothering you, your family doctor can determine your liver function tests with a simple blood test. Then you will know for sure.
Does the same precaution apply to well-controlled hypothyroidism without Hashimoto's?
Yes, especially then. Ashwagandha can additionally stimulate the body's own hormone production. Together with levothyroxine, the hormone level can rise above the carefully adjusted target range. Therefore, consult your doctor before taking it.
Which dosage form is better tolerated: powder, capsule, or extract?
None of the three is proven to be better tolerated, as comparative studies on tolerability are lacking. The capsule is only the shell. What matters is whether it contains powder or a concentrated extract. According to the BfR, the different preparations are one of the reasons why clear statements are difficult to make.
What should I tell my doctor if I talk about an adaptogen?
The name of the plant, the product including the recommended intake, how long you have been taking it, and all other medications and supplements you take. The easiest way is to bring the package with you. Symptoms you have noticed should also be included.
Does the same precaution apply to traditional powders such as Siberian ginseng?
Yes. The BfR warning applies generally to ashwagandha preparations, and a long tradition is no substitute for safety evidence. The same principle applies to Siberian ginseng: consult your doctor first if you take medication or have a pre-existing medical condition, then take it.
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