Many people are willing to go to extreme lengths to have longer-looking lashes. But the days of applying cumbersome fake lashes, extensions, or heavy amounts of mascara are shifting as lash serums have exploded into the mainstream beauty market.

A quality lash serum can deliver fantastic results turning lackluster lashes into noticeably longer, fuller lashes. However, a quick search on the web will misleadingly tell you all you need to grow your lashes is castor oil. 

Why to Avoid Castor Oil

  • This popular vegetable oil is said to help lashes grow fuller and longer. But the evidence is mostly anecdotal, with no solid scientific evidence to back up this claim. Even after months of a cumbersome, messy application process, many users report negligible effects at best. 

  • And, because castor oil is viscous and reflects light, it simply gives the illusion of longer, fuller lashes without having any real affect on growth. Plus, many castor oil serums contain additives and are not specifically formulated and tested for the eye area—which can cause irritation, redness, or worse if you accidentally get some in your eye. 

In addition to castor oil, let’s break down the disadvantages of the two other common synthetic solutions for longer lashes—false lashes and lash extensions. While tempting, fake eyelashes often require glue and can cause breakage of your real eyelashes upon removal. More often than not, they're made of cheap plastic which could also cause irritation or an allergic reaction. 

And, while extensions or falsies are often a go-to solution for a special occasion, continued upkeep can be expensive and cause our lashes more harm than good. That's why we at Smarter Reviews recommend investing in a quality lash serum over synthetic alternatives. 

A Quality Lash Serum:

  • Promotes longer & healthier lashes
  • Increases lash density for a fuller look
  • Is easier to apply from the comfort of your own home

But, there are a lot of lash serums available on the market, and many can be inherently costly, require a prescription, or even be risky to use due to certain ingredients that may cause harsh side effects. So when shopping for a lash serum, it’s important to know which ingredients to look for and which to avoid.

Top 5 Ingredients To Look For In Lash Serum

Red Clover Extract (Capixyl)

A clinically studied, vitamin-rich botanical containing lash-boosting peptides that support the structure of the follicles to promote fuller, healthier lashes. 


A protein that enhances the health of hair follicles and plays an important role in hair growth and thickness. It also helps prevent your lashes from weakening due to internal (hormonal) or external (toxins) stressors.


A lash-nourishing vitamin that keeps follicles strong and works in conjunction with other nutrients to promote growth and reduce inflammation in the roots.

Silk Amino Acids

Silk amino acids are the result of jelly-like proteins that help lock moisture into the lash

Vitamin B5 (Panthenol)

Vitamin B5 is a powerful lash-growth ingredient that helps moisturize lashes and boosts thickness. 

Finding a lash serum with the ingredients listed above is just the first step. There are some other important factors to consider before actually purchasing a lash serum. 

What To Avoid 


Most well-known brand name prescription & OTC serums contain prostaglandin analogs, which are synthetic chemical compounds with hormone-like effects. They've been known to cause adverse side effects like rashes, blurry vision, and drooping around the eyelids. Many labels might not openly disclose this information, so be sure to do your research. 

  • Parabens

    Chemicals including methylparaben, ethylparaben, and propylparaben can be absorbed through your skin and have been linked to serious long-term health conditions.

What Else to Consider When Buying a Lash Serum

Transparent List of Ingredients

Many lash serums only list a handful of their key ingredients. Make sure the lash serum you choose has a transparent list of ingredients so you know exactly what you're getting with no surprises.

Money-Back Guarantee

The beauty industry makes billions of dollars per year, which makes it easy for manufacturers with poor products to slip through the cracks. So make sure to buy a lash serum from a brand that’s willing to stand by its product with a 100% money-back guarantee.

Top 5 Lash serums Of 2021

When putting together our rankings, we consider the quality of ingredients, safety, return policies, projected effectiveness, and customer satisfaction.