I have rosacea and have read a lot about the benefits of niacinamide. I hadn't seen one at 20% so I had to check first to make sure it was safe. There's a big group of experts that says it's basically safe, but they tested on innocent furry creatures, so take that with a grain of salt. Most of what I find says they recommend around 2-5% because it absorbs pretty easily and some people might get irritation, redness or a reaction at higher levels. My skin is pretty habituated to niacinamide and with sensitive skin I'm used to watching it closely, so I dove right in. Let's call niacinamide 'b3' now, because it's the same thing and much easier to type. This is a glass bottle of clear liquid dispensed with a dropper, and pretty big compared to most I usually get. I don't really detect a scent. This isn't as moisturizing as I expected it to be, so I use this right before a moisturizing serum. This blends and absorbs quickly and easily, just don't use too much (note on that later). Please excuse the buildup on the photo of the dropper. I have been using this quite a bit but you'll notice there is yellow writing on the box that says sediment may occur on the bottle neck due to the high concentration, and I'm guessing that's what that is. This does seem to help, but it's worth noting that my rosacea hasn't been all that fussy these last few months. My pores seem a bit smaller and I haven't had much as far as inflammation, redness, or those annoying red bumps and crackly dry patches. I think this is probably a bit more effective than my usual b3 serum. I might see better results if I hadn't already been using pretty good products and my rosacea hadn't been in somewhat decent shape. I have noticed that if I use way too much, I can get a little chalky residue. That has only happened a couple of times. The first time I was really dry and wondering if I put more on if it would help the dryness. Instead, it left a faint white chalky residue on my skin. The second time I just got sloppy and dripped too much out. I think as long as you don't do that, this wouldn't be an issue. Worth noting, my ingredient checker found nothing 'icky' in this and multiple great ingredients. These include the sodium form of hyaluronic acid, which is basically the same thing, and some other moisturizing, soothing, and anti-acne ingredients. So I hope I didn't give you the impression that this is drying - that's just me, crackly, crackly, dry, me. I would recommend this for others with skin inflammation and redness, severe acne, anyone who wants to minimize pores and wrinkles or reduce hyper-pigmentation. I would watch for redness and whatnot if this is your first time using b3 and I would avoid this if you have those adorable freckles and don't want to fade them!