What is phototherapy?
Phototherapy is the use of light to treat medical conditions. Phototherapy involves exposing the skin to an artificial light source for a set length of time on a regular schedule, under medical supervision. The treatment schedule varies from two to five times a week and an average course lasts between 15 and 30 treatments. Treatments are done usually in a dermatology outpatient department.
Classically it is the ultraviolet (UV) part of the sun radiation that is used in phototherapy.
How does phototherapy work?
Ultraviolet light appears to inhibit the division of skin cells and also reduces the inflammation in the skin, therefore helping in various inflammatory skin disorders. However, although it can cause skin conditions to improve, this is usually temporary and not a cure.
What conditions can be treated with phototherapy?
UV light is used to treat various skin conditions such as psoriasis, atopic eczema, generalised itching, lichen planus, vitiligo, cutaneous T cell lymphoma, lichen planus, vitiligo, localised scleroderma etc. However, benefit is not observed in every case and, rarely, a patient's psoriasis or atopic eczema can be made worse by UV.
What are the factors that make the UV light treatment inadvisable?
- Past medical history of skin cancer.
- Treatment with a medicine which suppresses the immune system, such as ciclosporin or methotrexate.
- The maximum allowed number of light treatments in a lifetime has been already reached.
What are the potential side effects of phototherapy?
- The possible short-term side effects of phototherapy include sunburn, dry and itchy skin, and very rarely a sunlight-induced rash (such as polymorphic light eruption) or temporary worsening of skin disease.
- Potential long-term side effects of phototherapy include premature skin ageing and certain types of skin cancer (the risk of skin cancer is related to the total lifetime exposure to ultraviolet light, the risk is higher with repeated courses of phototherapy).
What are the new developments in phototherapy?
Classic light therapies use UV light, which can be damaging to skin and need to be administered under close medical supervision. In the past few years, several devices have been developed that use blue light only, without UV light and the investigations showed that blue light treatment is safe and efficient in the treatment of mild to moderate plaque psoriasis, stable eczema and mild to moderate acne.
In the case of psoriasis, the blue light is shone directly on the plaques and works by slowing down the accelerated production of skin cells. It also reduces the inflammation and has been shown to reduce the severity of psoriatic plaques.