An oral traditional Chinese herbal formulation in powder form containing a spray dried aqueous extract from the herbs Scutellaria baicalensis, Glycyrrhiza uralensis, Ziziphus jujuba and Paeonia lactiflora with potential immunomodulating and chemoprotective activities. Although the mechanism of actions remain to be fully elucidated, PHY906 possesses a wide range of pharmacological activities such as the enhancement of oral uptake of pharmacologically active agents, inhibition of CYP3A4, modulation of certain cytokines, macrophages and lymphocytes, and inhibition of expression of MMP, NF-kB, beta-glucuronidase, the NK-1 receptor, and the delta-opioid receptor.