Oregon Barberry (Mahonia aquifolium), also known as Oregon Grape, has a long history of traditional use among Native American tribes and herbalists for addressing fevers and colds. Historically, its roots and bark were used in decoctions or teas, often as part of broader remedies for infections, fevers, and digestive complaints. The main bioactive compound, berberine, exhibits antimicrobial and immunomodulatory properties in laboratory studies. However, these effects have not been specifically validated in clinical trials for the treatment or support of colds with fever. The traditional rationale was that Oregon Barberry could "cleanse the blood" or "reduce heat," concepts rooted in historical herbal medicine rather than modern scientific frameworks.

While some laboratory research supports the general antimicrobial and anti-inflammatory effects of berberine, there is currently no robust clinical evidence showing that Oregon Barberry or its extracts are effective in treating or reducing the duration or severity of colds, especially those accompanied by fever. Thus, the use of Oregon Barberry for colds with fever is primarily justified by traditional practice with limited scientific rationale, meriting an evidence rating of 2 out of 5.