Anxiety is not a commonly reported side effect of kava kava root, according to WebMD. However, practitioners of alternative medicine often recommend kava kava root as a treatment for anxiety. Alternative health professionals also recommend it for treating sleeplessness, restlessness, and muscle tension or spasms related to anxiety.
Side effects of kava kava root include temporary yellowing of the nails, skin and hair, and allergic skin reactions, notes WebMD. Users may also experience delayed reaction times, making it dangerous to drive or operate machinery during use. Kava kava root may cause severe side effects, including liver failure, prompting authorities in Britain to ban its sale.