The use of psoralen-UVA (PUVA) in patients of skin phototype I to II is limited by side effects of acute phototoxicity and possible long-term carcinogenesis.

We sought to assess oral Polypodium leucotomos (PL) extract in decreasing PUVA-induced phototoxicity of human skin on a clinical and histologic level.

A total of 10 healthy patients with skin phototypes II to III were exposed to PUVA alone (using 0.6 mg/kg oral 8-methoxypsoralen) and to PUVA with 7.5 mg/kg of oral PL.

Clinically, phototoxicity was always lower in PL-treated skin after 48 to 72 hours (P < .005), and pigmentation was also reduced 4 months later. Histologically, PL-treated skin showed a significant numeric reduction of sunburn cells (P = .05), preservation of Langerhans cells (P ≤ .01), decrease of tryptase-positive mast cell infiltration (P < .05), and decrease of vasodilation (P ≤ .01). No differences were found in Ki-67⁺ proliferating cells.

PL is an effective chemophotoprotector against PUVA-induced skin phototoxicity and leads to substantial benefits of skin protection against damaging effects of PUVA as evidenced by histology.