I'm having p.rosea right now almost 10weeks. And my doctors prescribe me a prednisone and im taking it almost a month. Does prednisone safe in my case?

Maybe, maybe not. Almost all medicines have potential adverse effects. The art of medicine is balancing those against their potential benefit. Side-effects of Prednisone are related to its dose and duration of taking. They include: diabetes, stretch marks on skin, thinning of bones, hypertension, psychiatric changes. Discuss with your doctor whether the ratio of risk to benefit is favorable for you.