Even though the use of Leonurus cardiaca, sometimes referred to as motherwort, developed separately in both Western herbalism and traditional Chinese medicine, many of its uses are the same in both systems. Extract of the plant's leaves and flowers have been traditionally used as a treatment for stress, insomnia, anxiety, nervous irritability, heart palpitations, delayed menstruation and cardiac weakness. The extract also has helped to heal muscle spasms, poor digestion, minor bleeding, diarrhea, gas, cramping, menopausal symptoms, difficult childbirth, and general heart weakness. Leonurine may be responsible for some of these medical applications as a result of its sedative, vasodilatory and muscle-relaxing properties. It is likely, however, that the plant's iridoid glycosides, labdane diterpenoids, flavonoids, tannins and essential oils also contribute to its pharmacological activity.
While most of the effects of Leonurus cardiaca are evident shortly after its administration, research suggests that the administration of an extract of the herb over many months may help reduce the activity of the thyroid in patients with hyperthyroidism. The use of the plant does not appear to result in a decrease in thyroid activity in healthy patients. As of 2011 more research is still needed to confirm these initial findings.
Closely related to the intoxicating herb Leonotis leonurus, the Leonurus cardiaca plant shares some of its sedative and anxiety-relieving properties. Both contain significant amounts of the alkaloid leonurine, the chemical generally believed to be responsible for much of the plant's use in herbal medicine. Research into some of the individual, non-alkaloidal constituents of Leonurus cardiaca has indicated that its phytochemical ursolic acid may exhibit antiviral, tumor inhibiting, cytotoxic and cardiotonic properties. This is much like the known Leonurus cardiaca exhibited in vitro cytotoxicity for breast tumors, colon tumors, KB cells, lung cancer cells and lymphocytic leukemia cells.
Due to its uses both as a cardiac tonic and muscle relaxant, Leonurus cardiaca is considered by the German Commission E to be a specific for the treatment of cardiac and menstrual symptoms associated with neurosis or anxiety disorders. Herbalist Michael Tierra also recommends using the plant to treat menstrual irregularities that may be stress-related. The use of this herb is not associated with any side effects, although some authors suggest that it may have minor blood-thinning properties and should not be used during pregnancy. Administration the herb immediately following labor should be limited to one dose to prevent increasing the risk of bleeding, though it may be used to address post-partum depression and tension after the uterus has clamped down.
While Leonurus cardiaca has traditionally been used in the form of a tea or concentrate, the active ingredients are quite bitter, making this preparation extremely unpalatable. It is possible to prepare glycerine extracts of the plant to be used in pregnancy, although ethanol extracts are more potent for other applications. The encapsulated dry herb is also useful, but large quantities must be used for it to be effective.