I'm always on the hunt for a product that's anti-aging, firming and also happens to lighten dark circles without causing dryness or irritation. This serum is the closest one yet, for me. After about a week of use, just at night, my undereye area began to look brighter and tighter. After a few more weeks, the dark circles lightened every so slightly. I honestly don't think any product is able to lighten genetic dark circles, so I give it a pass for not making much of a dent in them. But I really think my under eye area has improved as a result of this serum. In order to prevent dryness, I apply, let it sink in for a few minutes, and then put a rich moisturizer on top. It's never caused any problems of irritation or dryness, and it actually feels slightly moisturizing, which is rare for a serum. The serum isn't exactly cheap, for sure, but I get a few months' use out of a bottle when used about 4 nights a week.