Objective   To investigate the effects of blue light (407 to 420 nm) therapy on acne

facial sebum excretion rate and the growth of Malassezia furfur isolated from acne lesions.    Methods   Twenty cases of acne patients were treated with the blue light system. Before and after the treatments

electronic microscopy were used to assess the change of the target acne in epidermis and dermis. Looking bill and Cunliffe’s technique was used to test the sebum excretion rate (SER). Selected bacterial strains of Malassezia furfur were radiated with the blue light. The morphology and number of colony formation units (CFUs) of the bacteria were observed before and after the irradiation.    Results   Twenty cases of acne patients’ target acnes fade away remarkably and the injuries in the epidermis and dermis were alleviated. The SER was decreased significantly (P0.01) after the treatment of blue light. There was no coenobium of Malassezia furfur when the time of blue light irradiation exceeded 3.5 min. The number and diameter of the coenobium were in inverse proportion to the irradiation time.    Conclusion   The blue light can treat acne effectively

restore the damage even in the dermis

restrain the sebum secretion and kill the Malassezia furfur. It provides the experimental evidences for the treatment of acne.