In recent years phototherapy continues to be one of the essential therapeutic treatment options for patients with mild to moderate psoriasis, either as a monotherapy or in combination with other standard treatment modalities, such as systemic and topical agents.
There are two types of phototherapy for psoriasis, UVA and UVB and both have shown good response in treating psoriasis. UVB have shown to be more effective then UVB for treating psoriasis.
High dose UVB therapy is as effective as PUVA in treating patients with psoriasis and it can be used during pregnancy and lactation or in patients with hepatic or renal failure. There are two types of UVB therapy: Broadband UVB and Narrowband UVB. UVB treatment can be given on daily basis or 3-5 times a week until the lesion is cleared. Recently Narrowband UVB is being widely used as it has more advantage over Broadband UVB as it can be used in any patients including children and pregnant women.
UVA therapy penetrates deep into the skin than with UVB therapy. For UVA to be effective combination of UVA with photosensitizing medication like psoralen( PUVA) is used. Treatment is usually given 2-4 times a week until lesion clears. As PUVA make the skin more sensitive to light, one should avoid sun as much a possible.
Short-term side effects:
Dry skin with pruritus
The frequency of recurrent herpes simplex might increase.
Long-term side effects of UV therapy include
Increase risk of skin cancer
Loss of elasticity
Dark lentigines (“PUVA lentiginosis”).