Bidens pilosa, commonly known as Spanish needle or blackjack, has been traditionally used in various cultures to address inflammatory skin conditions, including dermatitis. Recent scientific studies provide some support for its use in this context, though the evidence is still emerging and primarily preclinical.

Research shows that extracts of Bidens pilosa possess significant anti-inflammatory and immunomodulatory properties. Laboratory (in vitro) and animal (in vivo) studies have demonstrated the plant’s ability to inhibit the production of pro-inflammatory cytokines and reduce oxidative stress, both key factors in the pathogenesis of dermatitis. For example, a 2020 study published in Phytomedicine found that topical application of Bidens pilosa extract reduced ear swelling and histological markers of inflammation in a mouse model of atopic dermatitis. The anti-inflammatory activity is attributed to compounds such as polyacetylenes, flavonoids, and phenolic acids present in the plant.

However, controlled clinical trials in humans are lacking, and most evidence comes from animal models or cell culture studies. While the traditional use and early scientific data are promising, further rigorous human research is needed to validate the efficacy and safety of Bidens pilosa for the treatment of dermatitis.