Ashwagandha

Ashwagandha is one of the most-hyped 'natural calm' supplements, and it does have reasonable evidence for stress, anxiety and sleep. The catch is the part the wellness ads skip: it's on the NIH's liver-injury registry as a 'likely' cause of clinically apparent liver damage. Real people have developed cholestatic hepatitis — jaundice and intense itching — after taking ordinary label doses, and while most recover after stopping, there are rare cases of liver failure needing a transplant. It can also nudge thyroid hormones up (a problem if you have thyroid disease) and has a traditional reputation as an abortifacient, so it's off the table in pregnancy. None of this makes it 'dangerous' for most people, but it's a herb to respect: pick a third-party-tested product and stop at the first sign of yellowing skin or itching.