Motherwort is known by its scientific name Leonurus cardiaca, and by several synonyms, like lion’s tail, heartwort, leonurus, and throwwort. The plant is native to Asia, but is now grown worldwide. For centuries, it’s been used as a blood thinner, a muscle relaxant, a way to regulate menstrual cycles, and as a way to regulate labor and reduce postpartum depression.
In the US, motherwort is sold as a nutritional supplement, and the US Food and Drug Administration (FDA) does not control its sale or verify its safety or effectiveness. It does appear to be relatively effective in thinning the blood based on laboratory studies, but this may not be a good thing. If you’re on blood thinners, motherwort may create bleeding problems when combined with drugs like aspirin or warfarin. It should never be used by a person with a cardiac condition without advice from a physician.
Further, concern exists about its use in stimulating or regulating labor. Since it can cause thinning of the blood, it increases risk of excessive bleeding during labor and postpartum recovery. Thus it can be a dangerous medication to use during labor. Women who are pregnant should never use it until just prior to onset of labor. Chinese herbalists prescribed motherwort as an abortive agent, and it may cause miscarriage.
Some women use motherwort to help regulate their periods, reduce the symptoms of pre-menstrual syndrome, and especially to reduce cramping. It does appear to have a mild sedative effect and relaxes the muscles, which may make this use legitimate. Further, anecdotal evidence has suggested that motherwort helps to alleviate or stop hot flashes and provides an overall sense of calm for women in menopause.
There have been several other historical uses for this herb. It may be used to treat insomnia, or to combat flatulence. As a muscle relaxant, this first use may make sense, but there’s little evidence that motherwort reduces gas.
Sometimes motherwort is combined with other herbs like mullein, and is used in cough and cold herbal remedies. Since it can relax the muscles it may ease coughing, and may have a mild anti-inflammatory effect on swollen tonsils. It is important to be careful when using a tonic of combined herbs, since all ingredients need to be evaluated as potentially contraindicated with certain conditions or if you take certain medications.
Despite warnings, some midwives who use herbal preparations, and of course, herbalists, do prescribe this herb to pregnant women. There is some difference of opinion on whether this is safe or effective. More commonly midwives may recommend its use only during and after labor. It is also thought to stimulate milk supply and may be recommended by lactation consultants.