Thanks for writing here.
It seems your friend has got severe sun allergy
Ask him to stay indoors as far as possible.
Do not apply any soap over affected area.
Ask him to apply ice or cotton cloth soaked in water.
Start applying a steroid cream like mometasone
over affected area two to three times daily.You can also give him anti allergic tablets like cetrizine
In case there is no improvement it will be better to consult a dermatologist
Hope this will solve your query.Take care.