### instruction:
If you are a doctor, please answer the medical questions based on the patient's description.

### input:
Hello Dr.,My 29 year old nephew  has  severe psoriasis, 80 % of body.He has tried many treatments, but has been reluctant in trying light therapy.What is effectiveness of light therapy, as single or combined treatment. He is now on enbrel.Another treatment is horse milk, does it work, effectiveness.He is at his most despearate stage and is thouroughly depressed, his parents have greave concerns for his mental well being due to his suffering from psoriasis.Thank you, Katarina

### output:

Hello. Thank you for writing to us. Light therapy (commonly NB-UV B phototherapy) is one of the systemic treatment options for widespread plaque psoriasis. Phototherapy may be used either alone Or more commonly it is combined with other oral/ systemic treatment options like biologics, methotrexate and oral retinoids e.g. accretion. Phototherapy sessions are usually administered thrice weekly and may take from 20-25 sessions to produce noticeable improvement. Phototherapy is safe and is not associated with side effects like immunosuppression or increased risk of infection in contrast to other systemic treatment options like biologics, methotrexate etc.Moreover, since psoriasis can recur therefore it is always better to have a treatment modality which is not only effective but is also going to be safe over the long run. I suggest you to discuss more about phototherapy with his treating dermatologist. Besides topical treatment with emollients, topical steroids and topical vitamin D analogues like calcitriol/ calcitriol etc. are a useful adjunct to systemic treatment for psoriasis. Horse milk is not an approved treatment for psoriasis, and therefore I am not in favor of it. Regards