Osha (Ligusticum porteri) has a long history of traditional use among Native American and Hispanic cultures in North America, particularly in the Rocky Mountain region. Traditionally, the root of the osha plant has been used as a remedy for various respiratory infections such as colds, coughs, sore throats, and influenza. It was often prepared as a tea, tincture, or chewed directly to help clear mucus, soothe irritated throats, and stimulate sweating to "break" fevers. The aromatic root contains compounds such as ligustilide, ferulic acid, and other phytochemicals with potential antimicrobial and anti-inflammatory properties, which may have contributed to its reputation as an infection-fighting herb.

However, scientific research specifically validating osha’s efficacy for treating infections in humans is limited. While some in vitro studies have shown that extracts of osha root possess mild antimicrobial and antioxidant activities, these findings have not been robustly confirmed in human clinical trials. Therefore, the use of osha for infection is primarily supported by traditional knowledge and anecdotal reports rather than strong scientific evidence. Caution is advised, as osha may cause allergic reactions in some individuals, and its overharvesting in the wild raises conservation concerns.