This is limited information and tells nothing about your skin condition which can help in planning a treatment. A thorough history, clinical examination will be needed to solve the mystery. Consider seeing a Dermatologist for proper diagnosis and treatment plan. Black spots could mean many things. I assume what you mean is probably post acne pigmentation or post inflammatory pigmentation. Targeting through a single agent may not always be fruitful. Meet a qualified Dermatologist to learn more about the diagnosis and treatment options. Combination of different therapeutic agents is always beneficial. Revlite I.e. Q-switched Nd YAG laser has been available for stubborn pigmentation and can be helpful when topical creams fail. Hope it helps