A multicentre clinical trial involving 1,200 adults has found no evidence of liver or kidney injury linked to daily use of a standardised Ashwagandha root extract over 24 weeks.

The randomised, double-blind, placebo-controlled study, published in Frontiers in Medicine on August 20, 2026, examined its safety and tolerability in adults who had received a first, second or booster dose of the COVISHIELD vaccine. Researchers from nine institutions, including the Central Council for Research in Ayurvedic Sciences (CCRAS), All India Institute of Ayurveda, National Institute of Ayurveda and other academic and clinical centres, conducted the study in seven sites across India 

Participants aged 18 to 70 were assigned to receive either 500 mg of a standardised aqueous Ashwagandha root extract daily—equivalent to 4 grams of raw root powder—or a matching placebo. During a 24-week intervention followed through week 28, 1,032 or 86% of the 1,200 participants enrolled, completed the study.

According to the researchers, liver and kidney function remained within the reported reference ranges throughout the trial. Laboratory assessments included liver enzymes, bilirubin, creatinine and blood urea. The study reported no evidence of treatment-related hepatic or renal injury.

No serious adverse events were considered attributable to the intervention, and no participant withdrew from the trial because of an adverse event, the researchers said.

The study also examined whether Ashwagandha affected the immune response following COVISHIELD vaccination. Virus-neutralising activity remained above 85% in both the Ashwagandha and placebo groups, with no statistically significant difference reported.

Lead author Dr Arvind Chopra said the findings provide evidence on the safety and tolerability of standardised Ashwagandha when used for 24 weeks under controlled clinical conditions. He also stressed the importance of evaluating Ayurvedic preparations through rigorous clinical research.

The researchers noted that the findings relate specifically to the standardised aqueous root extract, dosage and study population investigated, and should not automatically be extended to all Ashwagandha products or preparations.

The trial was registered with the Clinical Trials Registry–India under CTRI/2021/06/034496.

Reference: AYUSH;  Press Information Bureau