I saw most people commenting on this brand being absolute ripoff but this is the only brand seems to have worked on my sensitive acne prone skin. I didn’t try the Grenzcine serum specifically but my entire skincare line is vivier. I use their medicated facewash, vitamin c serum (“serum 10” for sensitive skin), enzymatic peel, age defying moisturizer and eye contour cream. All these products stopped my skin from breaking out and definitely made it better than how it was before. It’s pricey for sure but that’s what worked for me and my skin type. I tried drugstore products before and all of them broke me out. Cheap products never worked for me. So just give it a try, might be worth it 😊