Eyelashes - Lead
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They're advertised as the long-awaited secret to longer, thicker, and fuller eyelashes, but let's be real: Do lash serums work? work? We definitely encourage you to embrace your inner skeptic, but the good news here is — yes, they can work, but there are a few caveats.

For starters, let's dive into how they work. Dr. Joshua Zeichner, the director of cosmetic and clinical research in the Department of Dermatology at Mount Sinai Hospital in New York City, told InStyle that eyelash serums are responsible for two jobs. First, he says they hydrate and coat the surface of the eyelashes to volumize the hair itself. Second, he says they can either "directly stimulate the hair follicles or help create an optimal environment for hair follicle growth."

The major catch we mentioned earlier? It takes quite some time for them to kick into action. Dr. Zeichner told InStyle that some lash conditioners have the potential to show an immediate (but not long-lasting) effect because they're volumizing the lashes, but a change in length could take several weeks. That means you have to be committed to applying the serum daily, or as directed.

The one you can definitely expect results from, though, is an at-home treatment called Latisse. "It has the prostaglandin analog ingredient, which grows lashes plumper, longer, and more dense. Dr. Mark Jacquot, O.D., the clinical director at LensCrafters, says. "Prostaglandin analog was originally used in the initial formulation of Latisse to treat glaucoma patients. It was found that if it was applied directly to the lash line, the emphasis on lash growth is maximized."

It gets the doctor's stamp of approval, but the serum is only available with an Rx, and there are possible side effects like stimulating pigment in the eyes or on the eyelids.

On top of using the serum as directed, you can set yourself up for maximum eyelash growth potential by making a few lifestyle changes. "Eat a healthy diet that’s high in vitamins and proteins, don’t rub your eyes, as this increases the chances of eyelashes falling out, and remember to take your makeup off before you go to bed every night," Dr. Jacquot recommends. "Eye makeup can cause build-up over time and can cause eyelash loss."

VIDEO: 4 Ways to Apply At-Home Eyelash Extensions

Now that you know they're not a giant waste of money, scroll through this gallery of the best eyelash growth serums on the market to see which formula is right for you.