"Ordered the 5% glycolic cream first based on reviews--good idea. When my skin didn't tingle from the 5% anymore, I ordered the 10%. Wow! The tingle is there for sure! Obviously, those of us ordering this product are looking for cell turnover. The acid 'eats' the top layer off thus activating our skin to make new layers, thus a more youthful look. The 10% glycolic works! I have noticed a difference after using it for several weeks. However, I was over zealous and used it three nights in a row and my nose area and forehead peeled. Note, might want to use it every third or every other night with a intense moisturize in between."