GPs are being urged to be alert to liver injury caused by valerian, a complementary medicine typically used to treat menopause symptoms, sleeplessness and mild anxiety.

The TGA has announced it is investigating the safety of valerian (Valerian officinalis), a medicinal herb permitted in Australia and readily available over-the-counter without a safety warning.

Since 1983, there have been five cases of liver injury linked to valerian, with another 10 cases involving products that include the herb as an ingredient, according to the watchdog.

While cases were rare and most resolved after the herb was discontinued, three people had markers for severe liver injury and two required hospitalisation.