What is blue-light phototherapy?

Some degree of jaundice is common in newborns and is seen in up to 50% of infants between the second and fourth day of life. Before birth, bilirubin is conjugated and excreted chiefly by the placenta; however, after birth, this function shifts to the neonatal liver. Transient neonatal hyperbilirubinemia is the result of insufficient activity of the conjugative hepatic enzyme glucuronyl transferase. Phototherapy with blue light (460 nm) is an effective means of preventing hyperbilirubinemia by producing a photoproduct called photobilirubin, which is nontoxic. In the treatment of hyperbilirubinemia, phototherapy should be considered at serum bilirubin levels of 222 to 260 mmol/L, taking into account other clinical factors. Blue light phototherapy alone is also used to treat acne vulgaris. P. acnes is susceptible to blue light (415 to 425 nm) and is significantly reduced in number within the pilosebaceous unit. Improvement in acne is well documented.