Er Miao San: Two Marvels Powder
The formula is comprised of equal amounts of phellodendron (huangbai) and red atractylodes (cangzhu) ground to powder and swallowed down with ginger juice (if available; otherwise with water). In modern materia medica guides, phellodendron is classified with the herbs that clear heat and dry dampness; it is bitter and cold; red atractylodes is classified with the aromatic herbs that resolve moisture accumulation; it is spicy and warm, with some bitterness. Together, they dry dampness and treat a syndrome of damp heat, dispersing swelling and alleviating pain due to accumulation (2). In the traditional preparation, the herbs are fried, which is intended to yield a more drying effect. One of the principal indications for this formula is a disorder with yellow color: skin eruptions with pus, discharge that is discolored, dark yellow urine, yellow tongue coating, jaundice, and so on, though this coloration is not an essential requirement for use of the formula.
During the 1970s numerous reports emerged about the effectiveness of Ermiao San for treatment of exudative eczema, given orally or applied topically; reports of treatment of infants were included (3, 4). In the topical therapies, phellodendron was likely the main active component, serving as an antiseptic. Similar clinical use of phellodendron-alone and in formulas other than Ermiao San-was reported.
