Ashwagandha Side Effects: Risks and Safety Guide

If you’re one of the millions who take ashwagandha for stress or sleep, you’ve probably seen headlines about liver damage and regulatory bans. The herb’s reputation as a gentle adaptogen sits uneasily beside a growing number of clinical reports linking it to everything from stomach upset to severe jaundice. This article walks through what the evidence actually says, who should steer clear, and why Denmark decided to pull it from shelves.

Most frequently reported side effects: Stomach upset, loose stools, nausea, drowsiness ·
Serious side effects: Rare but include liver injury, thyroid hormone disruption ·
Regulatory action: Denmark banned ashwagandha in 2023 due to liver toxicity concerns ·
Common dosage range: 300–600 mg daily ·
Safety in pregnancy: Not recommended; may cause miscarriage

Five key facts about ashwagandha side effects and regulation:

For more on supplement safety, see our guide on Sea Moss Benefits: Health Claims, Risks and Evidence.

Are there negative side effects to ashwagandha?

Common gastrointestinal side effects

• Large doses of ashwagandha can cause diarrhea, nausea, and vomiting (NIH LiverTox (U.S. National Library of Medicine)).
• Upset stomach and loose stools are among the most frequently reported complaints in clinical trials (NIH LiverTox).

Neurological side effects (drowsiness, headache)

• Drowsiness and headache have been noted in clinical studies, though typically mild (NIH LiverTox).
• The sedative effect can be amplified if combined with other central nervous system depressants (Netherlands Pharmacovigilance Centre Lareb).

Serious side effects (liver injury, thyroid effects)

• Rare but clinically apparent liver injury has been linked to ashwagandha, typically presenting as cholestatic or mixed-pattern hepatitis with jaundice and pruritus (NIH LiverTox).
• Over 70 reports in the literature document liver damage ranging from mild injury to acute liver failure requiring transplant (University of Colorado Department of Medicine).
• Ashwagandha can disrupt thyroid hormone levels, worsening hyperthyroidism (Netherlands Pharmacovigilance Centre Lareb).

The implication: The rare but serious liver risk should make users weigh the benefits carefully.

Who should avoid ashwagandha?

Pregnant and breastfeeding women

• Ashwagandha may cause miscarriage and is not recommended during pregnancy (Univ. of Colorado).
• Safety during breastfeeding has not been established (NIH LiverTox).

People with thyroid disorders

• Ashwagandha can affect thyroid hormone levels and may worsen hyperthyroidism (Netherlands Pharmacovigilance Centre Lareb).
• Those on thyroid medication should have their levels monitored if taking ashwagandha (PMC case report review).

Individuals with autoimmune diseases

• Ashwagandha may stimulate the immune system, potentially worsening conditions like lupus or rheumatoid arthritis (Univ. of Colorado).
• Patients on immunosuppressants should avoid concurrent use (Netherlands Pharmacovigilance Centre Lareb).

Those scheduled for surgery

• Ashwagandha may interfere with anesthesia and blood pressure control during surgery (NIH LiverTox).
• Discontinuation at least two weeks before a procedure is advised (PMC review).

What this means: Four clear populations — pregnant women, people with thyroid disease, autoimmune patients, and surgery candidates — have documented reasons to avoid ashwagandha. The precaution is not theoretical; it’s based on pharmacological mechanisms and case data.

What not to mix with ashwagandha?

Sedatives and sleep aids

• Ashwagandha can increase the sedative effects of benzodiazepines, alcohol, and other CNS depressants, leading to excessive drowsiness (Netherlands Pharmacovigilance Centre Lareb).

Thyroid medications

• Because ashwagandha alters thyroid hormone levels, it may require dosage adjustment of thyroid replacement therapy (NIH LiverTox).

Immunosuppressants

• The herb’s immune-stimulating properties may counteract drugs like corticosteroids or cyclosporine (Univ. of Colorado).

Diabetes medications

• Ashwagandha can lower blood sugar, raising the risk of hypoglycemia when combined with insulin or oral antidiabetic drugs (PMC case report review).

The trade-off: Users often stack supplements without checking interactions. But ashwagandha’s effect on sedation, thyroid, immunity, and blood sugar means mixing it with even common prescriptions can produce unintended results.

For another perspective on medication safety, see Weight Loss Medication: Best Drugs, Costs & Eligibility.

Why shouldn’t you take ashwagandha daily?

Potential for cumulative side effects

• Daily use may increase the risk of gastrointestinal issues over time, especially at higher doses (NIH LiverTox).

Lack of long-term safety data

• Most clinical studies last 8–12 weeks; effects beyond three months are unknown (NIH LiverTox).
• The Netherlands RIVM advises against consuming supplements containing ashwagandha entirely due to insufficient long-term safety evidence (Netherlands Pharmacovigilance Centre Lareb).

Risk of developing tolerance or dependence

• Some users report reduced effectiveness over time, though formal evidence is lacking (PMC case report review).
• Dependence has not been documented in clinical literature, but the psychological reliance on a daily adaptogen is a grey area (Univ. of Colorado).

The pattern: Without long-term data, daily use remains an unquantified risk.

Why did Denmark ban ashwagandha?

Background of the ban

• The Danish Veterinary and Food Administration banned ashwagandha in 2023 after reviewing case reports linking the herb to liver damage (Netherlands Pharmacovigilance Centre Lareb).
• Denmark was the first EU country to take such a sweeping regulatory action (Univ. of Colorado).

Evidence of liver toxicity

• A case series of five patients — two from the US, three from Iceland — developed cholestatic or mixed-pattern liver injury after taking ashwagandha, with onset 2–12 weeks after first use (Netherlands Pharmacovigilance Centre Lareb).
• Laboratory findings showed elevated bilirubin and liver enzymes; all patients recovered after stopping the supplement (NIH LiverTox).
• One case report describes severe jaundice requiring hospitalization, with liver biopsy confirming drug-induced cholestasis (PMC case report review).

Current regulatory status in other countries

• The European Food Safety Authority began a safety review in 2024 (Univ. of Colorado).
• The Netherlands RIVM advises against consuming ashwagandha supplements (Netherlands Pharmacovigilance Centre Lareb).
• In the US, ashwagandha remains unregulated as a dietary supplement, with no FDA pre-market approval (NIH LiverTox).

“Harmful effects of ashwagandha-containing supplements can be serious and may occur even when people use them as directed.”

— Netherlands Pharmacovigilance Centre Lareb (Lareb report)

“Most ashwagandha-associated liver injury cases are mild-to-moderate and self-limited after stopping the product, but fatal acute liver failure or acute-on-chronic liver failure has been reported.”

— NIH LiverTox (U.S. National Library of Medicine)

“Over 70 reports in the literature have linked ashwagandha to liver injury, ranging from mild injury to severe jaundice and acute liver failure requiring transplant.”

— University of Colorado Department of Medicine (source)

Timeline

The timeline below summarizes key regulatory developments regarding ashwagandha safety.

The regulatory trajectory shows increasing scrutiny across Europe.

What we know and what remains unclear

Confirmed facts

• Drowsiness, nausea, diarrhea are common side effects (NIH LiverTox)
• Ashwagandha interacts with thyroid medications (Netherlands Pharmacovigilance Centre Lareb)
• Not safe during pregnancy (Univ. of Colorado)

What’s unclear

• Long-term safety beyond 12 weeks of use
• Exact mechanism of liver toxicity (PMC case report review)
• Whether side effects differ by gender or personality type

For anyone in the US considering ashwagandha, the choice is clear: start low, watch for warning signs like yellowing skin or unusual fatigue, and stop immediately if they appear. The alternative is risking a reaction that, while rare, could send you to the hospital.

Frequently asked questions