Four liver function tests were performed serially in 24 normal human subjects before, during, and after administration of 30 mg. of methoxsalen (8-methoxypsoralen) along with casual exposure to ultraviolet irradiation to 12 of the subjects, the remaining 12 subjects receiving placebos. In the group receiving methoxsalen, two subjects noted a slight increase in beard hair growth, and one reported "peptic ulcer" symptoms, which disappeared as the therapy was continued. Although a selected profile of liver function tests and blood constituents relating to liver function were within normal limits throughout the course of administration of methoxsalen, it cannot yet be concluded that the drug is safe for the general population.
Fitzpatrick TB, Imbrie JD, Labby D. EFFECT OF METHOXSALEN ON LIVER FUNCTION. JAMA. 1958;167(13):1586-1589. doi:10.1001/jama.1958.02990300012003