Ashwagandha Side Effects: What's Documented and What's Not

For most healthy adults, short-term ashwagandha is well tolerated, and the side effects people actually report are mild: an upset stomach, loose stools, and drowsiness.¹ That's the honest headline, and it's where most articles stop. It shouldn't be where you stop. A minority of people should not take ashwagandha at all — pregnancy is a flat contraindication, not a "check with your doctor" — and there are two rare-but-serious signals, liver injury and thyroid effects, worth understanding before your first capsule. One more thing the label won't tell you: the safety data only runs to about three months. Beyond that, no one really knows.¹ Here's what the evidence shows, separated cleanly from what people merely say online.

The common, mild side effects — the ones studies actually report

When ashwagandha causes problems in clinical trials, they're usually minor and dose-related. This is the evidence-backed tier: reported in controlled studies, not just anecdotes.

Stomach upset, nausea, and loose stools

Gastrointestinal complaints are the most common. The NIH Office of Dietary Supplements lists stomach upset, loose stools, nausea, and drowsiness as the typical mild effects.¹ They tend to show up early, tend to be dose-dependent, and often settle when you take the capsule with food rather than on an empty stomach. In the well-known 2012 trial of a 300 mg twice-daily root extract, adverse effects were mild and no more frequent than with placebo.¹⁴ If your stomach rebels, lowering the dose or moving it to a meal usually fixes it.

Drowsiness — the plant is literally named for sleep

The species name is Withania somnifera — somnifera meaning "sleep-inducing" — and mild sedation is a genuine, commonly reported effect.¹³ For someone taking it in the evening for stress or sleep, that's a feature. For someone dosing in the morning, it can be an unwelcome afternoon fog. If you feel groggy, shifting the dose to the evening is the obvious first move.

Headache and grogginess

Less common, and usually mild: some people report headaches or a heavy, dulled feeling, particularly at higher doses.¹ These are the kinds of effects that resolve on their own or when you cut back.

The rare but real one: ashwagandha and liver injury

This is the section the "generally safe and well tolerated" blogs skip, and it's the one that matters most. Ashwagandha can, rarely, injure the liver — and the signal is real, documented, and growing in the medical literature.

Keep the denominator in view first: ashwagandha use in the United States has surged into the millions of people, and clinically apparent liver injury remains rare against that backdrop.¹² Rare is not the same as never. The National Institutes of Health's LiverTox database classifies ashwagandha as a likely cause of clinically apparent liver injury — its likelihood score is "B" — and notes that cases, first reported in 2017, have increased since.² A 2026 systematic review of the published literature counted 37 reported cases.⁹ The true number is probably higher, because supplement-related injury is chronically underreported.⁷

The pattern is consistent across reports: injury typically appears 2 to 12 weeks after starting, usually as a cholestatic or mixed pattern with jaundice and itching.² The foundational 2020 case series from Iceland and the U.S. Drug-Induced Liver Injury Network described five patients — all developed jaundice and none progressed to liver failure, with liver tests normalizing within one to five months in the four who were followed.⁶ That's the reassuring end of the range. The other end is not: the 2026 review documented three deaths and one liver transplant among its cases, and LiverTox notes that rare fatal injury or the need for emergency transplant has occurred, concentrated in people with pre-existing liver disease.⁹² Researchers using the standardized RUCAM causality method have rated cases as probable, which is why the literature attributes the injury to ashwagandha itself rather than coincidence.⁷

Who should be most cautious: anyone with existing liver disease or cirrhosis, and heavy drinkers. LiverTox recommends avoiding ashwagandha in cirrhosis or advanced chronic liver disease outright.² Stacking it with other supplements that stress the liver adds risk you can't easily measure. And because what's actually in the bottle varies so much between products — more on that below — part of the danger is not knowing your true exposure.

Drug and condition interactions

Ashwagandha isn't inert, and its interaction profile is the reason a pharmacist should be in the loop if you take regular medication. The interaction box at the top of this page summarizes the key ones; here's the detail.

Thyroid medication

Ashwagandha can raise thyroid hormone levels, and both the NIH and Merck's professional reference flag a potential interaction with thyroid hormone medications such as levothyroxine.¹⁵ If you already take thyroid medication, ashwagandha could push your levels too high; if you have an overactive thyroid, it may add fuel to it. This is a "clear it with the prescriber first" situation, not a DIY experiment.

Sedatives, benzodiazepines, and alcohol

Because ashwagandha has its own mild sedative effect, it can add to the effects of central-nervous-system depressants. The NIH's complementary-health center notes that ashwagandha may increase the effects — and side effects — of sedatives and benzodiazepines.⁴¹ The same additive logic applies to alcohol and other drowsiness-causing medicines: combining them can leave you more sedated than you bargained for.

Immunosuppressants and autoimmune disease

Ashwagandha can stimulate immune activity, so in theory it may work against immunosuppressant drugs — the medications transplant recipients and some autoimmune patients depend on.¹⁵ For the same reason, people with autoimmune conditions such as Hashimoto's thyroiditis, lupus, or rheumatoid arthritis should be cautious: revving up an already overactive immune system is not obviously a good idea, and the evidence here is mechanistic rather than settled.

Diabetes and blood-pressure medication

Ashwagandha may lower blood sugar and blood pressure. Layered on top of antidiabetes or antihypertensive medication, that can add up to levels dropping further than intended.¹⁵ If you take either, monitor and talk to your prescriber before adding it.

Who should not take ashwagandha

Some people should simply skip it. This is where honest safety writing parts ways with the brand blogs — we say "don't," not "ask your doctor," where the evidence supports it.

• Pregnancy — do not use. This is a contraindication, not a caution. Merck's professional manual states ashwagandha should not be used during pregnancy because of possible abortifacient effects.⁵ It has a documented traditional use for inducing abortion, and it was one of the concerns behind Denmark's 2023 restriction of ashwagandha in food supplements.¹³ There is no data establishing it is safe in pregnancy, and good reason to think it isn't. If you are pregnant or might become pregnant, don't take it.
• Breastfeeding — avoid. There's no safety data for nursing infants, which is reason enough to stay off it.⁵¹
• Liver disease, cirrhosis, or heavy alcohol use — avoid, for the reasons in the liver section above.²
• Thyroid, autoimmune, or hormone-sensitive conditions — caution or avoid, and only with clinician sign-off, given the interactions above.¹
• Before surgery — pause it well ahead (a common rule of thumb is about two weeks). Its sedative effects can add to anesthesia and other perioperative drugs,¹ so stopping in advance is the cautious call.
• Children — not enough data to recommend it.¹

Side effects specific to men

Ashwagandha's reputation as a "testosterone booster" gets it framed as a men's supplement, so it's worth being straight about the hormonal angle. In a 2019 randomized trial in overweight men, an ashwagandha extract produced modest increases in testosterone and DHEA-S versus placebo over eight weeks.¹⁵ That's a real but small effect from a short study, and it isn't a reason to fear the supplement. It is a reason for caution in one specific group: because it can nudge hormones, men with a hormone-sensitive condition — hormone-sensitive prostate cancer in particular — should be careful and clear it with their oncologist first. For most men, the hormonal shift is minor; for that group, "minor" is still worth a conversation.

The "emotional blunting" question, handled honestly

Search around and you'll find people describing a flat, numb, unmotivated feeling after weeks of daily ashwagandha — "emotional blunting," apathy, a loss of the highs along with the lows. A prominent podcast figure popularized a caution about not using it continuously for more than roughly six weeks. So what's actually true?

Here's the honest landscape: this is anecdote-heavy and evidence-light. There is no controlled trial showing that ashwagandha causes anhedonia or emotional blunting. The controlled evidence generally points the other way — trials tend to report improved mood and lower stress markers, including reduced cortisol.¹⁴ But those trials carry real limitations: different extracts, small samples, short durations, and frequent industry funding. On the other side, the reports of feeling flat are lived experiences, not nothing — and a 2025 case report even documented apparent withdrawal-type symptoms after stopping ashwagandha, while explicitly noting that this is a single case, that alternative explanations are possible, and that no controlled evidence establishes such effects.¹¹

So we won't inflate this into a scare, and we won't wave it away. The plausible mechanism is unproven and the trial evidence for blunting is absent. Practically: if a few weeks in you feel emotionally muted, it is entirely reasonable to stop and see whether you return to baseline. You don't need a randomized trial's permission to notice you feel worse.

Quality, extract, and dose: why side effects vary so much

Two people can have completely different experiences with "ashwagandha" because they're not taking the same thing. The plant's active compounds are withanolides, and products vary widely in how much they contain and how they're standardized. The two most-studied branded extracts behave differently: KSM-66 is a root-only extract positioned for performance and stress, while Sensoril is a root-and-leaf extract with a higher withanolide content and a more sedating, calm-and-sleep profile. Same herb, different side-effect profile and dose.

Then there's the gap between what studies used and what's on the shelf. Many gummies deliver a fraction of the dose used in trials, while unverified capsules can swing the other way. And because the supplement market is loosely policed, products can carry contaminants — heavy metals, or ingredients that don't match the label — which is one more reason a case of liver injury is hard to trace to a cause. This is why third-party testing and a transparent, standardized product matter more than the marketing on the front of the bottle.

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How long is it safe to take?

Honestly? Nobody knows past a point. Most trials run 8 to 12 weeks, and the NIH's assessment is that ashwagandha "appears to be well tolerated for up to about 3 months of use," and that its long-term safety is not known.¹ That's the ceiling of the evidence. Taking it for many months or years is uncharted territory, and the popular advice to "cycle" it — a few weeks on, a few weeks off — is anecdotal rather than evidence-based. It's a reasonable-sounding habit, but say it plainly: no trial has shown that cycling prevents any harm.

The bottom line

For most healthy adults, short-term ashwagandha is well tolerated, and the common side effects — stomach upset, loose stools, drowsiness — are mild and manageable. The serious risks are rare but real: dozens of documented cases of liver injury, and a genuine interaction with thyroid medication, sedatives, and immunosuppressants. The hard lines are firmest in pregnancy — don't use it — and in liver disease. If you take prescription medication or have a chronic condition, talk to a pharmacist before you start, watch for the liver warning signs, and remember that the safety evidence runs out at about three months. This is educational information, not medical advice.

Frequently asked questions

What are the most common side effects of ashwagandha?

The most common are mild and gastrointestinal — nausea, loose stools, and an upset stomach — along with drowsiness. They're usually dose-related and often ease when you take ashwagandha with food or lower the dose. Serious effects are rare. If symptoms persist, stop and check with a clinician.

Can ashwagandha damage your liver?

Rarely, yes. Liver injury is documented, with dozens of published cases since 2017. Most were reversible jaundice that cleared after stopping, but rare severe cases — including liver failure and transplant — have occurred. Stop and seek care for jaundice, dark urine, or upper-right-abdomen pain, and avoid ashwagandha if you have liver disease.

Who should not take ashwagandha?

Do not take it if you are pregnant (possible abortifacient effect) or breastfeeding. Avoid it with liver disease, cirrhosis, or heavy alcohol use. Use caution — and get clinician sign-off — if you have thyroid, autoimmune, or hormone-sensitive conditions, or take sedatives, immunosuppressants, or thyroid medication. It isn't recommended for children.

Is ashwagandha safe to take every day or long-term?

It appears well tolerated for daily use up to about three months, which is as far as the studies go. Its long-term safety, over many months or years, is unknown. The popular advice to "cycle" it is anecdotal, not evidence-based. If you use it daily, keep the duration in mind and reassess.

Does ashwagandha cause emotional blunting?

Some people report feeling emotionally flat or unmotivated after weeks of daily use, but no controlled trial has shown that ashwagandha causes this. Trials generally report improved mood, with acknowledged limitations. The evidence for blunting is anecdotal. If you feel emotionally muted while taking it, it's reasonable to stop.

Can you take ashwagandha with medication?

It depends on the medication. Ashwagandha can interact with thyroid medication, sedatives and benzodiazepines, immunosuppressants, and diabetes and blood-pressure drugs. Because these interactions can be significant, ask a pharmacist or your prescriber before combining ashwagandha with any regular medication.