Edematous erythema at the hands and feet probably caused by the traditional herb "radix astragali".

Objective: To describe a patient with erhythema and edema after Radix Astragali was added to a kampo formula.

Case summary: A 21-year-old male, who was diagnosed as having atopic dermatitis in 1989, demonstrated systemic dry eruptions and consulted our department for treatment with traditional herbal medicine (THM) in 2004. The oral administration of herbal medicine resulted in decreased symptoms as well as a reduction in the serum IgE level. In August 2007, he complained of sweating on the neck and we added Radix Astragali to the previous formula. About 18 hours after he ingested the new formula including Radix Astragali, erhythema appeared with swelling of the bilateral hands and feet. Administration of the formula was discontinued and about 48 hours later, his symptoms had almost disappeared. Astragaloside, which is the main ingredient of Radix Astragali, was negative on lymphocyte transforming test (LTT) and we could not determine the ingredient that induced erhythema.

Conclusion: We consider that the Radix Astragali induced acute erhythema with swelling based on the clinical course. Acute edematous erythema due to THM is very rare and we discuss allergic reactions to traditional herbs and review the litrature.