Native to high altitudes in the Southwest and Rocky Mountain states, the root of the osha plant is a traditional Native American remedy for respiratory infections and digestive problems. A related plant, Ligusticum wallichii, has a long history of use in Chinese medicine, and most of the scientific studies on osha were actually performed on this species.
Osha is frequently recommended for use at the first sign of a respiratory infection. Like a sauna, it will typically induce sweating, and according to folk wisdom this may help avert the development of a full-blown cold. Osha is also taken during respiratory infections as a cough suppressant and expectorant, hence the common name "Colorado cough root." However, there have not been any double-blind placebo-controlled studies to verify these proposed uses. (For information on why double-blind studies are so important, see Why Does This Database Rely on Double-blind Studies?),
Chinese research suggests that Ligusticum wallichii can relax smooth muscle tissue (perhaps thereby moderating the cough reflex) and inhibit the growth of various bacteria.1 Whether these findings apply to osha as well is unknown.
Like other bitter herbs, osha is said to improve symptoms of indigestion and increase appetite.
Osha products vary in their concentration and should be taken according to directions on the label.
Osha is believed to be safe, although the scientific record is far from complete. Traditionally, it is not recommended for use in pregnancy. Safety in young children, nursing women, or those with severe liver or kidney disease has also not been established.
One potential risk with osha is contamination with hemlock parsley, a deadly plant with a similar appearance.2
1. Bensky D, Gamble A, Kaptchuk TJ. Chinese Herbal Medicine: Materia Medica. Seattle, Wash: Eastland Press; 1986:383–384.
2. Moore M. Medicinal Plants of the Mountain West: A Guide to the Identification, Preparation, and Uses of Traditional Medicinal Plants Found in the Mountains, Foothills, and Upland Areas of the American West. 1st ed. Santa Fe, NM: Museum of New Mexico Press; 1979:119.
Last reviewed December 2015 by EBSCO CAM Review Board Last Updated: 12/15/2015