Ashwagandha Side Effects
Ashwagandha is often marketed for stress and sleep, but “natural” does not mean risk-free. If you are considering it, or already using it for stress support, the main safety questions are fairly clear: stomach upset and drowsiness are the side effects people notice most often, and there are more serious concerns around liver injury, thyroid effects, and medicine interactions. This guide keeps the focus on what is known, what is uncertain, and when it is time to get help rather than wait it out.
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- Author: Supplement Explained
- Role: Editorial Publisher
- Last reviewed: March 27, 2026
- Last updated: March 27, 2026
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- Use: Informational only. Not personal medical advice.
Quick answer
The most commonly reported ashwagandha side effects are upset stomach, loose stools, nausea, and drowsiness. Those can happen early and may seem minor, but there are also more important safety concerns.
- Liver injury has been linked to ashwagandha in some people. Rare does not mean trivial.
- Ashwagandha may affect thyroid function and may interact with thyroid medicine.
- It may also interact with medicines for diabetes, blood pressure, sedation, and immune suppression.
- Short-term use up to about 3 months may be safe for some adults, but long-term safety is not clear.
- It may not be safe during pregnancy or breastfeeding, or for people with prostate cancer.
If you want a broader overview of the supplement itself, see our ashwagandha guide. If you are already having symptoms and are unsure what to do, start with when to talk to a clinician.
Key Takeaways
- Liver injury has been linked to ashwagandha in some people. Rare does not mean trivial.
- Ashwagandha may affect thyroid function and may interact with thyroid medicine.
- It may also interact with medicines for diabetes, blood pressure, sedation, and immune suppression.
- Short-term use up to about 3 months may be safe for some adults, but long-term safety is not clear.
What is clearly known
U.S. government health sources are fairly consistent on the main safety points.
- Common side effects usually include upset stomach, loose stools, nausea, and feeling drowsy.
- Short-term use appears to be tolerated by some adults, but long-term safety is still unclear.
- Rare cases of liver injury have been linked to ashwagandha supplements.
- A few studies suggest ashwagandha may affect how the thyroid gland works.
- Ashwagandha may interact with certain medicines, including thyroid medicines, diabetes medicines, blood pressure medicines, sedatives, and immune-suppressing drugs.
What is less clear is exactly who will develop a serious problem and why. That is why safety decisions should not rely only on whether a product is labeled herbal or sold over the counter.
Common side effects people notice first
The side effects many users notice first are digestive or sedating.
- Upset stomach
- Loose stools
- Nausea
- Drowsiness
These effects matter because they can be easy to dismiss. Stomach symptoms may be blamed on food or stress. Drowsiness may be mistaken for the reason someone started taking ashwagandha in the first place, especially if they were hoping it would help them feel calmer or sleepier.
But side effects are not something to push through casually. If drowsiness is strong, unexpected, or happens along with a sedative or sleep medication, that is not a “wait and see” situation. The combination can increase impairment and raise safety risks.
Liver and thyroid concerns
The two issues that deserve more caution than many shoppers realize are liver injury and thyroid effects.
Liver concerns: Both NIH sources note that ashwagandha has been linked to liver injury in some people. These reports appear to be uncommon, but they are important because liver problems can become serious if ignored. Unexplained jaundice, dark urine, or other signs that something is wrong should not be brushed off as a temporary supplement adjustment.
Thyroid concerns: A few studies suggest ashwagandha may affect how the thyroid gland works. That matters for people with thyroid disease, people being evaluated for thyroid symptoms, and anyone taking thyroid medication. New palpitations, unusual sweating, heat intolerance, shakiness, unexplained fatigue, or noticeable changes after starting the supplement deserve medical attention rather than self-experimenting.
If you have a history of liver problems or thyroid disease, a supplement that can potentially affect those systems is a good reason to check with a clinician before using it.
Medicine interactions and higher-risk groups
Ashwagandha may interact with several categories of medicine. The concern is not only whether the supplement “works,” but whether it changes the effect or safety of drugs you already rely on.
- Thyroid medicines
- Diabetes medicines
- Blood pressure medicines
- Sedatives
- Medicines that suppress the immune system
Extra caution is also warranted for some groups even before talking about interactions.
- Pregnant or breastfeeding people: ashwagandha may not be safe.
- People with prostate cancer: ashwagandha may not be safe.
- People with thyroid concerns, liver symptoms, or multiple prescription medicines: get individualized advice before starting.
If your health picture is complicated, the safer move is to review it with a clinician or pharmacist first rather than trying to sort out risk on your own.
When to stop guessing and get help
Do not treat the following situations as minor or routine:
- Drowsiness that is significant, feels unusual, or happens while you are also taking a sedative or sleep medicine
- Yellowing of the skin or eyes, dark urine, or other symptoms that could suggest liver injury
- New or worsening thyroid-related symptoms after starting ashwagandha
- Symptoms that begin after adding ashwagandha to thyroid, diabetes, blood pressure, or immune-suppressing treatment
- Any concerning reaction during pregnancy or breastfeeding
If you are unsure whether a symptom is worth acting on, it usually is. Use this clinician contact guide for practical next steps.
FAQ
Short answers to the questions readers most often ask before taking the next step.
What are the most common ashwagandha side effects?
The most commonly noted side effects are upset stomach, loose stools, nausea, and drowsiness.
Can ashwagandha cause liver problems?
It has been linked to liver injury in some people. The reports appear to be rare, but they are taken seriously. Symptoms such as jaundice or dark urine should not be ignored.
Does ashwagandha affect the thyroid?
A few studies suggest it may affect how the thyroid gland works. If you have thyroid disease, take thyroid medicine, or develop thyroid-type symptoms after starting it, get medical advice.
Is drowsiness from ashwagandha harmless?
Not always. Drowsiness is a known side effect, but it is more concerning if it is strong, unexpected, or happens along with sedatives or sleep medicines.
Who should avoid ashwagandha or be especially careful?
NIH sources say it may not be safe during pregnancy or breastfeeding, or for people with prostate cancer. Extra caution also makes sense for people with thyroid concerns, liver symptoms, or those taking medicines that may interact with it.
How long is ashwagandha considered safe to use?
NCCIH says short-term use up to about 3 months may be safe, but long-term safety is not clear.
Can ashwagandha interact with prescription medicines?
Yes. It may interact with thyroid medicines, diabetes medicines, blood pressure medicines, sedatives, and medicines that suppress the immune system.
Update Note
Last reviewed and updated on March 27, 2026. We revisit priority pages when important evidence, safety, labeling, or regulatory context changes.