I have consulted a dermatologist and he has given me a steroid composition, but is it safe to use it for a prolonged time?

Impossible to say: What is the underlying condition that the steroid cream is prescribed to treat?

Probably not: Consistent long-term steroid use on the skin is harmful. That being said, your dermatologist is well aware of the risks, can explain them to you in more detail if you wish, & has a plan in mind to fit your condition that in most cases would not require using the steroid cream long-term. Hope that helps.