Scrophularia root, also known as "Xuan Shen" in Traditional Chinese Medicine (TCM), has been used historically for a variety of skin conditions, including dermatitis. Traditional medical texts describe its properties as "cooling the blood," "clearing heat," and "detoxifying," which are interpreted as beneficial actions against inflamed and irritated skin. In TCM, dermatitis is often viewed as a manifestation of "heat" or "toxin" in the blood, and scrophularia root is included in various herbal formulas to address these imbalances.

Scientific research on scrophularia root's efficacy for dermatitis is limited. Some in vitro and animal studies suggest potential anti-inflammatory and antioxidative activities, but clinical trials in humans are lacking. The root contains iridoid glycosides (such as harpagoside), phenylethanoid glycosides, and other compounds with possible anti-inflammatory effects, which could theoretically benefit inflammatory skin conditions. However, there is not enough robust clinical evidence to confirm its effectiveness for dermatitis.

In summary, the use of scrophularia root for dermatitis is primarily justified by traditional use, supported by centuries of experience in TCM, but scientific validation remains limited. Individuals considering its use should consult healthcare professionals, as herbal medicines can interact with other treatments and may not be suitable for everyone.