PUVA therapy has been used to treat psoriasis, vitiligo, and various cutaneous diseases. Psoralens are metabolized in the liver and thus can produce liver damage.

This study was done to observe the effect of 5-methoxypsoralen on liver function during photochemotherapy.

Serum transaminase levels were determined before and during photochemotherapy in eighty patients with vitiligo or psoriasis.

Four of the eighty patients who had received 5-MOP-PUVA showed elevation of serum transaminase levels.

Although there have been few cases showing transient elevated values of serum transaminase during 5-MOP-PUVA, it is advisable to obtain liver function tests before and serially during photochemotherapy.