This product does exactly what it is supposed to do but here is what you need to know:  first, use it sparingly and only every other day if not every 2-3 days because it is really strong. Second, be careful when combining this with other skin products you are already using , i.e. tretinoin (Retin A) etc... and third, it will burn when you first start using it which is normal but that will stop. This product does work on dark marks. I am African American and this is the second bottle I have purchased and I am extremely happy with it.  Nothing else I have purchased has given me the same results.  The product can be used on other parts of the body besides the face. I started to see results within 2-3 weeks and I used it at night and used a sunscreen during the day.