Ashwagandha Side Effects, Drug Interactions & Who Should Avoid It

Ashwagandha is frequently described as a natural supplement for stress and sleep.

That can make it sound almost automatically safe.

For most healthy adults using standardized extracts for a few weeks or months, the available clinical evidence is reasonably reassuring.

But “generally well tolerated” is not the same as:

safe for everyone. Ashwagandha Side Effects

Ashwagandha can cause mild side effects such as:

stomach upset,

nausea,

loose stools,

and drowsiness.

More importantly, it may affect:

• thyroid function,
• blood glucose,
• blood pressure,
• immune activity,
• sedation,
• and possibly hormone-sensitive conditions.

There are also now enough published cases of ashwagandha-associated liver injury that the risk should no longer be dismissed simply because it appears rare.

The most accurate summary is:

Ashwagandha appears reasonably well tolerated during short-term use in many healthy adults, particularly when standardized single-ingredient root extracts are used. However, rare but potentially serious liver injury has been documented, thyroid effects are biologically and clinically plausible, medication interactions are possible, and major health authorities advise avoidance or extra caution during pregnancy, breastfeeding, surgery, thyroid disease, autoimmune disease, and certain medication use. Ashwagandha Side Effects

That is the safety profile buyers should understand before choosing an ashwagandha supplement.

Important: This article is educational and is not medical advice. If you take prescription medication, have a medical condition, are pregnant or breastfeeding, have liver or thyroid disease, or develop unusual symptoms after starting ashwagandha, discuss the supplement with an appropriate healthcare professional.

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Ashwagandha Safety at a Glance

Question	Current Evidence
Generally tolerated short term?	Yes, in many controlled trials
Common side effects	GI upset, nausea, loose stools, drowsiness
Rare liver injury?	Yes, documented
Can affect thyroid function?	Yes, evidence suggests it can
Pregnancy	Major U.S. guidance recommends avoiding
Breastfeeding	Avoid due insufficient safety data
Autoimmune disease	NCCIH recommends against use
Before surgery	NCCIH recommends avoiding
Medication interactions	Possible with several drug classes
Long-term safety	Still less certain than short-term safety
Best-studied population	Generally healthy adults using standardized extracts

Best Ashwagandha Supplement in 2027: 7 Top Picks Compared

Is Ashwagandha Generally Safe?

For many healthy adults, short-term clinical-trial data are reassuring.

NIH’s Office of Dietary Supplements states that ashwagandha is generally well tolerated for approximately:

up to three months

in many studies, with adverse effects usually mild. Ashwagandha Side Effects

A newer 2026 systematic review focused specifically on standardized root-only extracts.

It included:

23 studies

and:

2,317 participants

using roughly:

125–600 mg/day

for durations ranging from a single dose to:

180 days.

Across those trials, hepatic, renal, hematological, endocrine, and cardiovascular biomarkers generally remained within normal clinical ranges, and no clinically meaningful pattern of adverse laboratory effects was identified.

That is encouraging. Ashwagandha Side Effects

An even larger 2026 randomized multicenter trial involved:

1,002 adults

and compared:

600 mg/day ashwagandha root extract

with placebo for:

8 weeks.

No serious adverse events occurred, and liver, kidney, and hematological laboratory measures remained within normal ranges.

So why do safety concerns remain?

Because randomized trials and rare adverse-event reports answer different questions.

Trials are good at detecting:

common side effects.

They are much less capable of detecting:

rare idiosyncratic reactions occurring in perhaps a very small fraction of users.

That is exactly where liver injury enters the discussion.

What Are the Most Common Ashwagandha Side Effects?

NIH and NCCIH identify mostly mild short-term effects, including:

• stomach discomfort,
• nausea,
• loose stools or diarrhea,
• vomiting,
• and drowsiness.

Large doses may be particularly likely to cause gastrointestinal irritation.

LiverTox notes that higher oral doses can produce:

nausea, vomiting, diarrhea, and gastrointestinal upset.

For many people, those symptoms resolve after the supplement is stopped. Ashwagandha Side Effects

But not every new symptom should automatically be attributed to ashwagandha.

The more useful question is whether the symptom:

• began after starting the supplement,
• improves after stopping it,
• returns with repeat exposure,
• or is accompanied by warning signs requiring medical evaluation.

Can Ashwagandha Cause Liver Damage?

Yes—but apparently rarely.

This is one of the most important updates to the modern safety picture.

Older descriptions of ashwagandha often stated that serious liver toxicity had not been observed.

That is no longer accurate. Ashwagandha Side Effects

LiverTox, maintained by the National Institute of Diabetes and Digestive and Kidney Diseases, now classifies ashwagandha as a:

likely cause of clinically apparent liver injury.

Reported cases most commonly developed after approximately:

2–12 weeks

of use.

Typical presentations include:

• jaundice,
• itching,
• elevated bilirubin,
• and a cholestatic or mixed pattern of liver injury.

Most reported cases eventually improved after discontinuing ashwagandha.

But recovery can take:

weeks to months.

Rare severe outcomes have also occurred.

What Does the New 2026 Liver-Injury Review Show?

A 2026 scoping review identified:

25 patients

across 13 published reports of ashwagandha-associated liver injury.

The most common biochemical pattern was:

cholestatic or mixed liver injury.

Jaundice and itching were common.

Most patients recovered after discontinuation and supportive care.

However, severe outcomes included:

• one liver transplantation,
• and three deaths among patients with pre-existing cirrhosis who developed decompensation.

That distinction is critical.

For a healthy person, the absolute risk appears low.

For someone with:

advanced chronic liver disease or cirrhosis

the consequences may be considerably more serious. Ashwagandha Side Effects

LiverTox therefore advises avoiding ashwagandha in people with advanced chronic liver disease.

What Symptoms Could Suggest Liver Injury?

Seek appropriate medical attention if new symptoms develop such as:

• yellowing of the skin or eyes,
• unusually dark urine,
• persistent itching,
• pale stools,
• significant nausea,
• unusual fatigue,
• or abdominal discomfort

after starting ashwagandha.

These symptoms do not prove ashwagandha caused liver injury. Ashwagandha Side Effects

But continuing the supplement while significant jaundice or systemic symptoms develop would not be sensible.

Why Do Clinical Trials Look Safe If Liver Injury Exists?

Because rare adverse events can easily escape a trial.

Imagine a reaction occurs in:

1 out of several thousand users.

A study involving:

100 participants

or even:

1,000 participants

could easily report zero cases. Ashwagandha Side Effects

That does not contradict the case-report literature.

It simply means:

short-term population-level tolerability appears good while rare idiosyncratic reactions remain possible.

This distinction is important for nearly every dietary supplement.

Can Ashwagandha Affect the Thyroid?

Yes.

This is another issue that deserves more attention.

A randomized placebo-controlled trial studied:

50 adults with subclinical hypothyroidism.

Participants received:

600 mg/day ashwagandha root extract

for eight weeks. Ashwagandha Side Effects

Compared with placebo, ashwagandha significantly:

• lowered TSH,
• increased T3,
• and increased T4.

That study was investigating a possible therapeutic effect in people with subclinical hypothyroidism.

But from a safety perspective, it tells us something important:

ashwagandha can influence thyroid physiology.

NIH therefore warns that ashwagandha may interact with thyroid medications. Ashwagandha Side Effects

Can Ashwagandha Cause Hyperthyroidism or Thyrotoxicosis?

Rare case reports suggest that it may contribute in susceptible people.

One published case involved a 73-year-old woman who developed:

• thyrotoxicosis,
• symptoms of hyperthyroidism,
• and supraventricular tachycardia

while using ashwagandha. Ashwagandha Side Effects

Her symptoms and thyroid tests improved after the supplement was discontinued.

Another 2024 case described:

painless thyroiditis

after approximately two months of ashwagandha use in a previously healthy 47-year-old man.

Again, symptoms and thyroid markers improved after discontinuation.

Case reports cannot establish how common the risk is.

But combined with the randomized trial showing changes in TSH, T3, and T4, they make it unreasonable to treat ashwagandha as thyroid-neutral.

Who Should Be Especially Careful?

People with:

• hyperthyroidism,
• hypothyroidism,
• Hashimoto’s disease,
• Graves’ disease,
• thyroid nodules under evaluation,
• or thyroid medication use

should not assume ashwagandha is harmless simply because it is sold over the counter. Ashwagandha Side Effects

NCCIH currently lists thyroid disorders among the situations where ashwagandha is not recommended.

Can Ashwagandha Interact With Thyroid Medication?

Potentially.

If ashwagandha independently increases T3 or T4 or changes TSH, combining it with:

levothyroxine or other thyroid treatment

could theoretically alter the intended treatment effect. Ashwagandha Side Effects

This does not mean every combination causes a dangerous interaction.

It means thyroid medication dosing is precise enough that adding a supplement capable of affecting thyroid hormones deserves professional review.

Can Ashwagandha Interact With Diabetes Medication?

Potentially.

Ashwagandha has been investigated for effects on blood glucose.

A 2026 systematic review of 11 randomized trials found a modest average reduction in fasting blood glucose, although the HbA1c evidence remained inconclusive.

That makes an interaction with glucose-lowering medications biologically plausible.

NIH and NCCIH both list antidiabetes medications among potential interaction concerns.

Someone taking:

• insulin,
• sulfonylureas,
• metformin,
• GLP-1–based therapies,
• or another diabetes medication

should not change medication based on supplement use. Ashwagandha Side Effects

The relevant issue is whether combining therapies alters blood glucose enough to require clinical monitoring.

Can Ashwagandha Interact With Blood-Pressure Medication?

Potentially.

NCCIH specifically includes:

antihypertensive medications

among drugs that may interact with ashwagandha.

Again, this does not mean every combination is dangerous. Ashwagandha Side Effects

But someone already taking medication to lower blood pressure should avoid assuming that an herb with physiological effects cannot contribute additional changes.

Ashwagandha and Sedatives

Drowsiness is one of the better-recognized ashwagandha adverse effects.

That raises an obvious concern when it is combined with:

• sleeping medication,
• anti-anxiety medication,
• sedating antihistamines,
• certain pain medicines,
• or other CNS depressants.

NCCIH lists sedatives among possible medication interactions.

The concern is not that ashwagandha is equivalent to a prescription sedative.

It is that sedating effects may potentially add together. Ashwagandha Side Effects

If someone is already using medication for sleep or anxiety, adding another sleep-oriented supplement deserves more caution than it would in a medication-free healthy adult.

Ashwagandha and Anti-Seizure Medication

NCCIH also lists:

anticonvulsant medications

among possible interactions. Ashwagandha Side Effects

Someone with epilepsy or another seizure disorder should therefore not experiment with ashwagandha without professional guidance.

This is particularly important because changing seizure-medication effectiveness can have serious consequences.

Ashwagandha and Immunosuppressants

Ashwagandha is often marketed as supporting immune function.

That becomes a potential problem when someone is deliberately taking medication to:

suppress immune activity.

NCCIH advises caution with immunosuppressant medications and also does not recommend ashwagandha for people with autoimmune disorders.

Examples where this concern may become relevant include people using immunosuppression for:

• organ transplantation,
• inflammatory conditions,
• autoimmune disease,
• or certain cancer treatments.

The interaction depends on the drug and condition. Ashwagandha Side Effects

It should not be guessed from a generic internet interaction list.

Should People With Autoimmune Disease Avoid Ashwagandha?

NCCIH currently recommends against ashwagandha use in people with:

autoimmune disorders.

The theoretical concern is that altering immune activity may be undesirable in conditions where immune regulation is already abnormal.

Examples include:

• rheumatoid arthritis,
• lupus,
• multiple sclerosis,
• autoimmune thyroid disease,
• and others.

Not every autoimmune condition is identical. Ashwagandha Side Effects

But this is one of the situations where self-directed supplement experimentation is much less appropriate.

Is Ashwagandha Safe During Pregnancy?

Major current U.S. guidance recommends:

avoiding ashwagandha during pregnancy.

NCCIH explicitly says it should be avoided.

NIH ODS also notes longstanding concerns about possible abortifacient effects.

However, this topic deserves nuance. Ashwagandha Side Effects

A 2025 systematic review examined the historical and scientific basis of claims that ashwagandha causes abortion or fetal harm.

The authors found that some traditional warnings were based on weak or repeatedly cited secondary evidence, while animal studies did not consistently demonstrate reproductive toxicity at relevant doses.

That does not establish safety during pregnancy.

It simply means:

the evidence that ashwagandha directly causes miscarriage is less certain than some warnings suggest.

Because high-quality human pregnancy safety data are lacking, the practical recommendation remains conservative:

avoid ashwagandha during pregnancy unless an appropriate clinician specifically recommends otherwise.

Pregnancy is not a situation where an absence of proven harm should be interpreted as proof of safety.

Is Ashwagandha Safe While Breastfeeding?

There is insufficient reliable evidence establishing safety for:

• the breastfeeding parent,
• breast-milk transfer,
• or the nursing infant.

NCCIH therefore says ashwagandha should not be used while breastfeeding.

This is primarily an evidence-gap issue. Ashwagandha Side Effects

There is not enough high-quality lactation research to justify routine use.

Why Should Ashwagandha Be Stopped Before Surgery?

NCCIH specifically recommends against use in people who are about to undergo surgery.

Potential concerns include:

• sedative effects,
• blood-pressure effects,
• blood-glucose effects,
• thyroid effects,
• and interactions with perioperative medications.

That does not mean ashwagandha has been proven to cause surgical complications. Ashwagandha Side Effects

It means a multi-system botanical is not something the anesthesiology and surgical teams should discover only after a procedure has started.

If surgery is planned, tell the healthcare team about:

all supplements

—not just prescription drugs.

What About Prostate Cancer?

NIH and NCCIH both note concerns for people with:

hormone-sensitive prostate cancer

because some research suggests ashwagandha may increase testosterone in certain populations. Ashwagandha Side Effects

Evidence on testosterone is not consistent enough to claim that ashwagandha dramatically raises testosterone in everyone.

But when someone has a hormone-sensitive malignancy, even a potential hormonal effect deserves greater caution.

Does Ashwagandha Cause Heart Palpitations?

Palpitations are not among the most consistently reported common side effects.

However, thyroid stimulation can indirectly produce:

• rapid heart rate,
• palpitations,
• tremor,
• heat intolerance,
• and anxiety-like symptoms

if thyrotoxicosis develops.

The published case involving supraventricular tachycardia illustrates this possibility. Ashwagandha Side Effects

So a new rapid heartbeat after starting ashwagandha should not automatically be dismissed as “detox” or an adaptogenic adjustment.

Is a Higher Dose More Dangerous?

Possibly, depending on the extract and outcome.

Higher doses can increase gastrointestinal exposure and potentially increase the likelihood of mild side effects.

But the rare liver reactions described in the literature appear largely:

idiosyncratic

rather than simply a predictable toxicity that occurs once a particular dose is exceeded.

That means taking a low dose cannot guarantee zero risk. Ashwagandha Side Effects

And taking a high dose does not automatically cause liver injury.

The more useful principle remains:

use a research-relevant dose of the exact extract rather than exceeding the label because “more must work better.”

Our ashwagandha dosage guide explains the research ranges by KSM-66, Sensoril, Shoden, and other preparations.

Are Root-Only Extracts Safer Than Root-and-Leaf Extracts?

We cannot conclusively say that. Ashwagandha Side Effects

The 2026 systematic review of 23 studies found standardized root-only extracts reassuring across more than 2,300 participants.

But that does not prove:

root-only is inherently safer than root + leaf.

It simply means the review deliberately evaluated one class of standardized preparations.

Different extracts have:

• different phytochemical profiles,
• different withanolide concentrations,
• different manufacturing processes,
• and different clinical datasets.

Safety evidence should therefore be tied as closely as possible to the actual extract being used.

Does “Third-Party Tested” Eliminate Safety Risk?

No.

Third-party testing can help verify things such as:

• identity,
• heavy-metal contamination,
• microbial contamination,
• and label accuracy.

That is valuable.

But it cannot eliminate:

• individual allergy,
• medication interactions,
• thyroid responses,
• or rare idiosyncratic liver injury.

Testing answers:

“Is the product what it claims to be?”

It does not necessarily answer:

“Is this ingredient appropriate for this particular person?”

Both questions matter. Ashwagandha Side Effects

How Long Can You Safely Take Ashwagandha?

NIH and NCCIH remain cautious because most evidence is short term.

General guidance still states that ashwagandha appears reasonably tolerated for:

about three months

while longer-term safety is less established.

Newer 2026 evidence is encouraging. Ashwagandha Side Effects

The root-only systematic review included trials extending as long as:

180 days

without a consistent pattern of clinically meaningful laboratory abnormalities.

A separate 12-week study even tested:

2,000 mg/day

of a root extract in healthy adults and found no serious clinical safety signal, with laboratory values remaining in reference ranges.

But these findings should not be stretched into:

“Ashwagandha is proven safe forever.”

Six months of trial data is not the same as:

five years,

ten years,

or indefinite supplementation. Ashwagandha Side Effects

Who Should Avoid Ashwagandha?

Based on current government guidance and clinical safety concerns, the strongest caution applies to people who are:

pregnant

breastfeeding

preparing for surgery

or have:

thyroid disease

autoimmune disease

advanced chronic liver disease

or:

hormone-sensitive prostate cancer. Ashwagandha Side Effects

Additional caution is appropriate for people taking:

• diabetes medication,
• blood-pressure medication,
• thyroid hormone,
• immunosuppressants,
• sedatives,
• or anti-seizure medications.

This does not mean every person in those categories will experience an interaction. Ashwagandha Side Effects

It means the available evidence is not strong enough to assume routine unsupervised use is appropriate.

When Should You Stop Taking Ashwagandha?

Stop and seek appropriate medical advice if you develop concerning new symptoms such as:

• jaundice,
• dark urine,
• severe itching,
• persistent vomiting,
• marked abdominal pain,
• rapid or irregular heartbeat,
• tremor,
• unexplained weight loss,
• significant rash,
• or symptoms of a serious allergic reaction.

Also reconsider continued use if you develop persistent:

• diarrhea,
• nausea,
• excessive drowsiness,
• or another symptom that consistently appears after supplementation.

A supplement is optional. Ashwagandha Side Effects

There is no reason to tolerate meaningful adverse effects simply to complete an arbitrary eight-week trial.

Frequently Asked Questions

The Bottom Line

So, is ashwagandha safe?

For many generally healthy adults using a reputable standardized extract for a relatively short period:

the evidence is reassuring.

A 2026 systematic review covering:

23 trials and 2,317 participants

found standardized root extracts generally well tolerated across doses of roughly 125–600 mg/day, with no consistent pattern of clinically significant changes in liver, kidney, blood, endocrine, or cardiovascular markers. Ashwagandha Side Effects

A separate:

1,002-person randomized trial

found no serious adverse events after eight weeks of 600 mg/day root extract.

But that is only half of the safety story.

Rare liver injury is real enough that:

LiverTox now classifies ashwagandha as a likely cause of clinically apparent liver injury.

A 2026 review identified 25 reported patients, most presenting with cholestatic or mixed liver injury, jaundice, and itching.

Most recovered after stopping the supplement.

But severe outcomes occurred particularly among people with pre-existing chronic liver disease.

Ashwagandha can also affect thyroid function. Ashwagandha Side Effects

One randomized trial showed meaningful changes in:

TSH, T3, and T4

after eight weeks, while rare cases of thyrotoxicosis and thyroiditis have been reported.

And major U.S. guidance currently recommends avoiding or using additional caution with ashwagandha during:

pregnancy

breastfeeding

thyroid disease

autoimmune disease

upcoming surgery

and certain medication use.

So the correct conclusion is not:

“Ashwagandha is dangerous.”

And it is not:

“Ashwagandha is natural, so it is completely safe.”

It is:

Ashwagandha has a reasonably reassuring short-term safety profile for many healthy adults, but it is biologically active, can interact with health conditions and medications, and carries rare but potentially serious risks that deserve appropriate screening.

That is especially important when choosing a supplement.

A good ashwagandha product should not be judged only by:

• how many milligrams it contains,
• how high the withanolide percentage is,
• or how many reviews it has.

Also consider:

the standardized extract

the research-relevant dose

third-party quality testing

your medications

your health history

and:

whether ashwagandha is appropriate for you in the first place. Ashwagandha Side Effects

For our comparison of finished products by extract, dose, standardization, testing, value, and intended use, see our Best Ashwagandha Supplements guide.