Is rexol good for post inflammatory hyperpigmentation as a result of acne?

It's an option. Rexsol lighteners contain hydroquinone. Use it sparingly or you can disfigure yourself. The pigmented lesions fade in a few weeks or months. I'm more concerned that you get the new ones under control. If topical benzoyl peroxide has not cleared you in two weeks, get with your personal physician.