Alisma has been used for centuries in China. It is also used in North America and Europe. In the categories used by traditional Chinese medicine, which classifies herbs according to energy level (hot, warm, cool, or cold) as well as taste, alisma is said to have a cold nature and a sweet, bland taste.

It is used primarily to treat conditions of damp heat associated with the kidney, bladder, and urinary tract. Alisma is a diuretic and is used to rid the body of excess water. It has mild and safe tonic qualities that especially affect the kidney and bladder. It is often combined with other herbs in general tonic formulas.

It is used to treat kidney stones, pelvic infections, nephritis, and other urinary tract infections, as well as yellowish discharges from the vagina. Alisma is believed to have an antibacterial action that helps control infection. In China, alisma is used to help rid the body of phlegm, to reduce feelings of abdominal bloating, and to treat diabetes.

The herb is also widely used in Japan. Outside of China, alisma leaves are sometimes used medicinally. They can be applied externally to bruises and swellings, or taken internally to treat kidney and urinary tract inflammations. The roots are used for kidney and urinary tract disorders, as well as to lower blood pressure and to treat severe diarrhea.

A minor homeopathic remedy can also be made from the root. Modern scientific research shows that alisma does act as a mild diuretic. In several studies done in Japan, alisma extracts were shown to reduce artificially induced swelling in the paws of rats.

Studies using human subjects have not been done, but test tube and animal studies do seem to indicate that there is a scientific basis for some of the traditional uses of alisma. There is also some indication that alisma does have a mild antibacterial effect, but again, evidence in humans is anecdotal and by observation rather than by controlled trials.

Fresh alisma roots and leaves are poisonous. Dried roots or cooked leaves are safe, even in fairly large doses. However, the kidney infections that alisma is used to treat can be serious. Anyone who suspects that they have a kidney infection should see a medical practitioner.

Some Chinese herbalists indicate that long-term use of alisma can irritate the intestines. In China and Japan, alisma is often taken together with antibiotics for kidney infections without any negative interactions. Since alisma is primarily an Asian herb, there is no body of information on how it might interact with most Western pharmaceuticals.