A large multicentre clinical trial has found that daily use of a standardised Ashwagandha root extract for 24 weeks was well tolerated, with no evidence of treatment-related liver or kidney injury.
The study, published in Frontiers in Medicine on August 20, 2026, involved 1,200 apparently healthy adults aged 18 to 70 years who had received a first, second or booster dose of the COVISHIELD vaccine.
The randomised, double-blind, placebo-controlled trial was conducted across seven sites in India by a multidisciplinary team of 45 researchers from nine institutions, including the Central Council for Research in Ayurvedic Sciences (CCRAS), All India Institute of Ayurveda, National Institute of Ayurveda, Jaipur, and other institutions working in clinical and integrative health research.
Participants were randomly assigned to receive either 500 milligrams of a standardised aqueous Ashwagandha root extract daily, equivalent to four grams of raw root powder, or a matching placebo. The intervention continued for 24 weeks, with participants followed up until week 28.
Of the 1,200 participants enrolled in the study, 1,032, or 86 per cent, completed the trial.
The researchers reported that liver and kidney function parameters remained within the reported reference ranges throughout the intervention period. Assessments included liver enzymes, bilirubin, creatinine and blood urea, with no evidence of treatment-related hepatic or renal injury.
No serious adverse events were considered attributable to the study intervention, and no participant discontinued the trial because of an adverse event.
The study also examined whether Ashwagandha affected the immune response following COVISHIELD vaccination. Virus-neutralising activity remained above 85 per cent in both the Ashwagandha and placebo groups, with no statistically significant difference between them.
Lead author Dr Arvind Chopra said the findings provide evidence on the safety and tolerability of standardised Ashwagandha use over a 24-week period. He also highlighted that the extract did not interfere with vaccine-induced immunity.
The study was registered with the Clinical Trials Registry–India under registration number CTRI/2021/06/034496.
The researchers said the findings add to the clinical evidence on standardised Ashwagandha preparations and underline the importance of conducting rigorous, well-controlled studies to assess Ayurvedic interventions and support their evidence-informed use.
