Hello, Both are not safe for the skin. Hydroquinone may cause severe skin redness, burning, or stinging, severe skin dryness, cracking, or bleeding, blisters or oozing or blue or black discoloration of the skin. Tretinoin also causes skin tingling, itching, redness, swelling, dryness, peeling, scaling, irritation, discolored skin. Please consult your dermatologist before starting above creams. Hope I have answered your query. Let me know if I can assist you further. Regards, Dr. Penchila Prasad Kandikattu