Ashwagandha appears to be safe, but more long-term research specifically designed to evaluate its safety is needed. Ashwagandha may cause mild drowsiness and sedation for some people.[1][2][3][4]
Some case reports have suggested adverse effects such as rash or thyroid dysregulation may occur with ashwagandha use, but the same has not yet been observed by safety studies with larger samples.[5][6][1] Several case reports have also raised concerns regarding the rare occurrence of liver toxicity with ashwagandha use, but similarly, toxicity has not been observed in clinical safety trials. In the reports, liver toxicity was usually reported within 2–12 weeks of ashwagandha use, and liver function returned to normal in all but one case following medical support and ashwagandha discontinuation.[7][8][9][10][11][12] An in vitro study suggested that withanone (one type of withanolide in ashwagandha), may have toxic effects in the context of low levels of the cellular antioxidant glutathione (GSH), which is involved in drug detoxification.[13] However, this research is far from conclusive and the mechanisms underlying this possible adverse effect are unclear.