I bought this to help fight off a persistent cluster of breakouts. With consistent use over about two months (morning and evening) I saw clear improvement. It's hard to say for certain how much of the healing was due to this product, but I do feel like it helped, and I do feel like my skin really liked it. Once I ran out of the product I haven't needed to repurchase, because the major breakout situation was resolved.
The consistency is like a lotion. It's smooth and easy to use, easy to spread on the skin. It has no discernible smell to me. Before this I tried the azelaic acid by The Ordinary, but really had issues with the smell and consistency of that product. So I did much prefer the Paula's Choice azelaic acid booster from the two.
The instructions say you could either use it alone or mix it in with your moisturizer. I only used it on specific areas of my face without mixing into anything, and that worked for me.
I also want to point out that I believe mixing this product with your moisturizer is a bad idea. Azelaic acid has been shown to be effective at pretty high concentrations. The 10% that this product has is already kind of low, so you really don't want to further dilute it.
The main downside of this product to me is the price, which is relatively high for the small amount of product that you're getting. Of course if you're able to use it as a spot treatment, it's going to last longer. But if you're using all over the face, you'll run out very quickly. Overall I just think the price is a bit steep, although it is a good product.
The concentration of 10% azelaic acid is also pretty low compared to the concentrations that have been shown to be effective in studies.
