Most psoriasis patients have experienced improvement of their skin lesions after sun-exposure. However, some patients complained of exacerbation of their symptoms by sun-light. We usually call it as photosensitive psoriasis.

This study aimed to know whether psoriasis patients have increased photosensitivity through comparison of minimal erythema dose(MED) of UVB between psoriasis patients and normal healthy volunteers.

The MED of 52 psoriasis patients and 39 normal healthy volunteers was deter-mined by gradual increase of UVB in 10 mJ/cm², starting from 30 mJ/cm². And we used independent sampled T-test to evaluate statistical significance.

The UVB MEDs obtained from lower back of psoriasis patients and normal subjects were 79.2 20.9 mJ/cm² and 64.4 21.9 mJ/cm² respectively (p<0.05). It was significantly higher in psoriasis patients than normal subjects.

This study demonstrates that the photosensitivity is not problematic in managing Korean psoriasis patients compared with normal healthy volunteers in Korea.