Epimedium 8 is based on a modern Chinese formula called Wenyang Tang (Warm the Kidney Yang Decoction), also known as the kidney reinforcing regimen. It has been shown to help prevent seasonal asthma attacks, normalize adrenal production of corticosteroids, and positively affect hormone receptors in aged persons. This is a modification of Rehmannia Eight Combination (Jingui Shenqi Wan) and the Pill of Right Restoration (Yougui Wan) retaining the common base ingredients rehmannia, dioscorea, and aconite to nourish the kidney. Here epimedium and psoralea are used to tonify kidney yang in place of the cinnamon bark used in the original formulas; they have a more gentle warming effect. Cuscuta, an ingredient of Yougui Wan, is used as the essence astringent in place of cornus; ophiopogon is used to nourish the yin in balancing the warming yang tonics. Epimedium with ophiopogon helps strengthen the lungs. A similar strategy is applied in Cordyceps 9, using epimedium and asparagus; ophiopogon and asparagus are closely related botanically and have similar properties. The small dose of citrus is added to aid in digestion of the rich tonics. Some concern is often raised by practitioners about kidney warming therapies: do they tend to cause the person to become overheated? In most cases, this will not be a problem because significant yang deficiency leads to "floating yang," a condition that produces heat symptoms in the upper body (usually with cold in the lower body); by using an appropriate yang tonic formula, the yang is rooted in the kidney and does not produce heat symptoms (in fact, some deficiency heat symptoms are thereby relieved).

Yin Yang Huo (epimedium) 18% Shu Di (rehmannia) 18% Shan Yao (dioscorea) 15% Bu Gu Zhi (psoralea) 14% Tu Si Zi (cuscuta) 14% Fu Zi (aconite) 9% Mai Men Dong (ophiopogon) 9% Chen Pi (citrus) 3%