I use this product to fight sunspots and acne at the same time. If you are trying to choose between the 8% and 15%, start with the 8% first and work your way up because this is a stronger serum. You might experience some mild stinging. The consistency is very fluid, almost like water, but one pump is just the right amount. I like that it’s not heavy because it’s no problem layering my moisturizer on top.