Can Lash Serum Be Used on The Brow. Lash serums are a very popular cosmetic product used to grow lashes, thicken lashes and darken lashes. The eyebrow is also important and there are serums to thicken the brow, darken the brow and help grow brow hair. Some of these can age the eye and cause dark circles. Some contain growth factors and some contain prostaglandins. The prostaglandins can indeed age the eye so application and methods of applying are important. Anteage Brow serum does not use prostaglandin but instead uses growth factors.