Latisse.

"There's a side effect that's super rare -- I don't think I've ever seen it in somebody who's used a prostaglandin analog eyelash serum, but it has been seen with glaucoma drugs, and that is pigmentary change in your iris, which is the colored part of your eye. The concerning thing about this side effect is that if it does happen, it's permanent. It's usually more common in green or hazel eyes, and people end up getting a brown speck in their eye. I used to recommend these eyelash serums because for a long time they were the only options with real efficacy, but that has changed. There are now lash serums that grow lashes through different mechanisms and they are mostly peptide-based without the prostaglandin risks, and those are what I recommend."

"Latisse is the brand name and Allergan is the parent company. This happens to be bimatoprost, which is the active ingredient inside of this, and this is actually the prostaglandin analog that is doing the work. Even though when they were using these eye drops and testing them and finally got them for over-the-counter use, people also started noticing other side effects, and that's why you always hear Latisse being advertised like on TV and it's like might cause darkening of the eye. That's actually true. When they were studying Latisse, they found that it caused a little bit more pigmentation, not just in the iris, that donut-shaped colored ring in your eye, but also around the eye. When you apply this Latisse, it comes with these little spoolie brushes and you're meant to paint these onto the eye area, but some people saw that the areas that they painted it on had a little bit of darkening and pigmentation. The pigmentation of the iris, the donut-shaped color ring, those didn't reverse when they stopped using it, but for some people, they did see a reversal of the pigmentation that was actually on the eyelash lid. When you actually use Latisse, it says specifically do not apply to the under lash area or the under eye area, only apply to the top."