Your Lash Serum Companion: A Guide to Application, Safety, and Results

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Do you thirst for naturally longer and thicker lashes? If so, you need to pick up a lash serum. Lash serums can power up your lashes naturally, improving their thickness and length. They amp up your eyes’ natural frame for days when you’re not in the mood to wear makeup. In this post, we’ll cover everything you need to know about lash serums, including how they work, how to use them, and more! 

What Is Lash Serum?

A lash serum is a product intended to be applied along the lash line to improve the density and intensity of the eyelashes. The formula penetrates the hair follicle and boosts its action. Most lash serums are formulated with ingredients known to stimulate or improve the functioning of the hair follicles, including peptides, plant extracts, or prostaglandin analogs. 


How Does Lash Serum Work?

Lash serums work differently depending on their active ingredients, but most have a water-based formula that penetrates into the follicles at the base of the lashes. 

Some lash serums utilize natural ingredients, including peptides, growth factors, and plant extracts. These ingredients are chosen for their nourishing effect that stimulates better lash growth or for their ability to inhibit the factors that lead to lash loss. Clinical research shows that these types of formulas are able to improve lash length and density. 

Other popular formulas rely on ingredients called prostaglandin analogs, which are believed to work by stimulating and prolonging the growth phase of the lashes, which leads to longer lashes and better lash density.   

Benefits of Using Lash Serums

If you’ve been considering using a lash serum, these are the key benefits you can expect: 

  • Lash density: Your lash line will look denser and fuller thanks to a reduction in lash shedding. 
  • Length: Over time, your lashes will likely appear longer and a little curlier, as well, thanks to a longer growth period. 
  • Color: Depending on the serum, you may also see darker and more lustrous lashes. 
  • Ease of use: Lash serums are effortless to apply and work well alongside most skincare routines. 
  • Pair with extensions: Most lash serums can be used alongside lash extensions to help keep the lashes healthy and strong. 

How Often Should You Use Lash Serum? 

Lash serum should be used once every day. The best time to use it is at night, when your lashes are otherwise clean, and the serum will have time to sink in and do its magic. To make sure that you’re consistent, make using lash serum a regular part of your nighttime routine, just like brushing your teeth or flossing. 


How to Apply Eyelash Serum

Here’s how to apply lash serum, step-by-step, with a few added tips that’ll make the process as simple as possible. 

Step 1 - Clean and Prep the Eye Area

Always start with clean eyes prior to applying your lash serum. If you’re wearing contact lenses, make sure to remove those before applying the serum, as well. 

If you’re wearing eye makeup, take it off completely with the help of makeup remover. If your makeup remover is oil-based, consider washing your eyes a second time with a cleanser or micellar water to remove any oil residue that might prevent the serum from penetrating. 

If you’re wearing lash extensions, make sure to clean them thoroughly with a lash shampoo and brush.

Step 2 - Apply to Upper Lash Line

Most lash serums come in a small tube with a thin brush built into the cap. Unscrew the cap, and then use the brush to apply the lash serum along the base of your lash line from above. 

If you’ve ever applied liquid eyeliner, this is a similar process. If you have hooded eyes, you can slightly pull on your lid to reveal the skin at the base of your lash line to ensure a closer application. 

The liquid will do its job seeping in between the lashes, so you don’t need to worry about “tightlining” it on. 

Step 3 - Apply to Lower Lash Line 

Finally, apply the eyelash serum to your lower lash line. Brush it on from below your lash line - not in the waterline. The closer you apply it to the root of your lashes, the better. Once you’re done, you can continue with your evening routine! 

Choosing the Right Lash Serum

With so many different lash serums to choose from, here are our tips for making sure you choose one that really works: 

  • Opt for water-based formulas: While oil-based lash serums can be nourishing to the lashes themselves, they don’t have the ability to penetrate and stimulate the lash follicles to the same extent. If you’re looking for significantly longer lashes, water-based serums are the way to go. 
  • Keep it affordable: Lash serums work best when you use them consistently, so make sure to choose a formula that’s not overpriced. Excellent lash serums don’t have to break the bank to show amazing results! 
  • Clinically proven ingredients: Look for a formula and ingredients that have been clinically tested, to ensure both safety and efficacy. Knowing that there’s clinical testing behind a product will also give better insight as to how long before you can see results and what kind of effects you can expect. 
  • Think twice about prostaglandin analogs: Prostaglandin analogs like bimatoprost, the active ingredient in Latisse, are generally very effective, but they come with added side effects that peptide and plant-based formulas don’t have. You can still achieve amazing results without them, so they’re not a must. 

How Long Does Lash Serum Take To Work?

How long a lash serum takes to work largely depends on the type of lash serum you use and how often you use it. With once-daily use, you can expect to start to see results within four to 10 weeks, which is about how long the lashes take to go through a full life cycle. This is also the amount of time usually spent on clinical research, and it’s when most researched lash serums show the most dramatic results. 

What Happens When You Stop Using a Lash Serum?

Because of the short life cycle of the lashes, the effects of using a lash serum are short-lived.  Once you stop using your lash serum, your lashes will probably go back to normal within a few months. You’ll be able to enjoy longer, thicker-looking lashes for as long as you continue to use a lash serum. Once you achieve your desired results, you can take occasional, short breaks.


What to Do in Case of Irritation?

In some cases, eyelash serums can irritate the eye area. This is pretty rare and is more likely to occur with lash serums that include prostaglandin analogs. This is also more likely to occur if you apply lash serum without properly cleansing the eye area first. 

If you do experience irritation because of lash serum, stop using the product, and wait for your eyes to return to normal. You can use eye drops or a cold compress to address any dryness or discomfort. If the irritation persists or it impacts your eyesight, seek medical care immediately, and consult a medical professional before attempting to use eyelash serums again in the future.  


Can You Use a Lash Serum With Eyelash Extensions?

Yes! Using an eyelash serum is a great way to keep your lashes healthy even while wearing lash extensions. Eyelash serums are actually applied to the lash line rather than the lashes themselves, so your extensions don’t get in the way of results. Eyelash serums are very compatible with Lilac St.’s DIY lash extensions since they adhere from below the lash line rather than from above it.  

FAQs About Lash Serum

Can you use eyelash serum with mascara?

You can if you want to, but we don’t recommend it. It’s best to apply your lash serum in the evening after you’ve already taken your makeup off for the night. If you do want to use both at the same time, apply your lash serum first, make sure it sinks in completely, and only then apply your mascara and other eye makeup products. 

Can you use eyelash serum on your eyebrows?

Yes, although the results aren’t guaranteed. The hair on the lashes and brows largely serves the same function of keeping debris out of the eyes, so lash serums work in a similar way on the brows. That means that lash serums will likely succeed in improving overall brow density, but the chances of growing new hair where there was previously no growth at all is less guaranteed.  

Are lash serums safe?

Lash serums are made with cosmetic ingredients that are largely considered safe. That said, applying anything so close to the eyes comes with some potential risks, especially if you have any pre-existing sensitivities. 

Both allergies and irritation can lead to redness, swelling, itchiness, or dryness around the eyes. If you experience any symptoms like that, you may want to stop using lash serums altogether. If you know that your eyes are pretty sensitive, consider conducting a patch test for a few days before starting to use your lash serum regularly. 

There are some reported cases of loss of orbital fat and hyperpigmentation using lash-enhancing products made with prostaglandin analogs like isopropyl cloprostenate (which is found in cosmetic lash serums) and bimatoprost (which is found in lash-enhancing drugs). 

Achieve Longer Lashes, Naturally 

Having naturally long lashes is a dream for many of us! What could be better than having perfectly framed eyes, without the need for mascara or extensions? If you’d like to enhance your lashes naturally, a lash serum can definitely help by prolonging your lash growth cycle and preventing breakage. The key is to pick up a lash serum that’s proven to work and to use it consistently - you’ll be surprised to learn just how lush and long your lashes could be, naturally! 

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Maya Adivi

Make Up Artist | Beauty Writer

Maya Adivi is a makeup artist and beauty writer originally from Toronto, Canada. She’s passionate about all things makeup, skincare, and beauty. She takes a science-based approach to writing, ignoring the marketing buzz in favor of facts and re...