Is Prolonged Use Of Betnesol For Treatment Of Vitiligo,harmful?

Hi, I am 34 yr old and suffering Vitiligo for last 25 yrs. Tried everything but no result. But Betbesol forte tablet combined with Vitamines tabl. helps atleast not spreading this disease(i am taking this on advice of skin specialist). One of my friend is Ortho doctor and advised me not to take Betnesol for long time as it's very strong steriods and will have very bad long term effect and after few years it will decrease immunity of my body and i will be more prone to getting more diseases. Is that true....???

How harmful is betnesol use if we take it got long term say 5-10 year.