5-Hydroxy-8-methoxypsoralen (5-Hydroxyxanthotoxin) is a metabolite derived from Xanthotoxin, which acts as a potent tricyclic furocoumarin suicide inhibitor of CYP (cytochrome P-450). It is employed as an agent for the treatment of psoriasis, eczema, vitiligo, and certain cutaneous Lymphomas, in combination with phototherapy involving exposure to sunlight.