Common valerian is a perennial plant that reaches up to 1.5 meters in height. Native to Europe and Asia and naturalized in North America, valerian has an erect, grooved stem that bears four to eight pairs of leaves. Each leaf is made up of seven to ten pairs of toothed leaflets, which are usually 5 to 7 centimeters long. The plant flowers from June to August, bearing clusters of small, pinkish-white blossoms. The fruit is a pale brown, oval-shaped capsule, containing a single seed. Valerian has a short, thick, yellowish-brown root, which is used for health purposes.
Valerian root has a history of medicinal use dating back over 2,000 years. It appears in the writings of ancient physicians Dioscorides and Pliny, who prescribed it for a wide variety of internal and external applications, as did the 17th century British herbalist Nicholas Culpeper.1 The root was used as bait by rat-catchers, and the legendary Pied Piper of Hamelin was said to have employed it to lure rats from the village.2 Modern use of valerian root centers on its mild sedative properties.
Valerian contains a number of active compounds, including valepotriates, valerenic acid, lignans, sesquiterpenes, and monoterpenes; all of which may contribute to the herb's sedative effect. However, the valepotriates are unstable and rarely present outside of the fresh root. Valerian extracts are often standardized for valerenic acid content.
Germany's Commission E recommends 2-3 grams of dried valerian root (or extracts providing the equivalent) several times per day, and there are no known side effects at this dosage. Mild, transient symptoms of toxicity have been reported in a patient taking approximately 20 times the recommended dose.