Derived from the root of the plant V. officinalis, valerian is sold as a dietary supplement for calmness, sedation, and to improve sleep quality. Other species including V. jatamansi, V. fauriei, and V. wallichii are also used in traditional medicine to treat insomnia and anxiety. Valerian products are usually available in extracts or teas that have a distinct odor.

In preclinical studies, valerian showed antioxidant ⁽¹⁾, cytoprotective ⁽²⁾, neuroprotective ⁽³⁾, antihypertensive, antispasmotic ^(4) (5), anxiolytic ⁽⁶⁾, and antidepressant ⁽⁷⁾, but not sedative ⁽⁸⁾ effects.

Clinical findings indicate improvements in anxiety ⁽⁵⁹⁾ and sleep quality ^{(9) (10) (11) (60)}, but the sleep-inducing properties were not superior to placebo ^{(12) (13) (14) (15)}. Valerian also failed to improve sleep in a study of cancer patients ⁽¹⁶⁾. Other studies suggest valerian may improve sleep and anxiety in HIV patients on antiretroviral therapy ⁽⁵³⁾, reduce hot flashes ^(17) (54) and dysmenorrhea ⁽¹⁸⁾, facilitate supervised benzodiazepine withdrawal ⁽¹⁹⁾, relieve symptoms of obsessive-compulsive disorder ⁽²⁰⁾, and have a positive affect on mental energy ⁽⁶¹⁾. However, sample sizes in these studies were too small to draw firm conclusions. Other reviews also concluded the evidence for valerian as an anxiolytic is insufficient ^(21) (22).

The valerian derivative isovaleroxy-hydroxy dihydrovaltrate showed anticancer effects against human ovarian cancer cells in vitro and in vivo ⁽²³⁾. Chlorovaltrates in valerian had moderate cytotoxicity against lung, prostate, colon and liver cancer cell lines ⁽²⁴⁾. But a case-control study found valerian to be positively associated with risk of early-onset colorectal cancer ⁽⁶²⁾. Clinical trials have yet to be conducted.

Although valerian products are generally safe, liver and pancreatic toxicities have been reported ^{(25) (26) (27)}. Valerian is also thought to have estrogenic effects ^(17) (28), but this was not observed in vitro ⁽²⁹⁾.