My 10 Yrs Old Son Is Having Two Small White

my 10 yrs old son is having two small white spots. one under eye & one in armpit. doctor diagnosed vitiligo. he prescribed melgain ( apply in mor & exposure to sun after coming back from school at 1.30 in afternoon. he also suggested to apply elidel cream on spots in night. want to know how safe & effective this treatment is? do v need to take any other treatment also or to avoid some thing in diet to prevent it. pls advice