Yerba Mansa (Anemopsis californica) has a long history of traditional use among Indigenous peoples and herbalists in the southwestern United States and northern Mexico, particularly for ailments related to the respiratory tract and sinuses. Traditionally, the root and rhizome of Yerba Mansa have been prepared as teas, tinctures, or poultices to address symptoms such as sinus congestion, inflammation, and infections. Some ethnobotanical sources suggest its use for alleviating sinusitis, catarrh, and other upper respiratory discomforts, likely due to its perceived anti-inflammatory and mild antimicrobial properties.

However, scientific validation for Yerba Mansa’s efficacy in supporting the sinuses is limited. While a few preliminary in vitro studies indicate antimicrobial activity of Yerba Mansa extracts against certain bacteria and fungi, there is a lack of rigorous clinical research specifically evaluating its effect on sinus health or its mechanism of action in vivo. Thus, its use for sinus support is primarily rooted in traditional practice rather than contemporary scientific evidence.

In summary, Yerba Mansa's reputation for supporting the sinuses is based mostly on historical and ethnobotanical practices, with only modest supportive evidence from basic laboratory studies and none from human clinical trials.