Nail hardeners have been a staple in the nail salon †for decades, but oftentimes they leave behind a sticky residue. We’re here to help you find a nail hardener that is safer for your skin and that is made with ingredients you can actually pronounce.

In the Health & Beauty Lab we test nail hardeners for performance, safety and ingredients. After testing dozens of nail hardeners for performance and safety, we scored them based on how nicely they harden nails, how quickly they dry, how thick they apply, how much they cost, and how well they last. We also looked at each nail hardener’s ingredients, including those that are known to cause allergies or irritation. We looked for ingredients like formaldehyde, toluene, camphor, and DBP, which can harm your skin and eyes. We also rated how easy they were to remove.

Below, we share our favorite nail hardener without formaldehyde. This formula hardens nails neatly, dries quickly, is easy to apply and doesn’t leave any sticky residue.

What is nail hardener and how does it work

Nail hardener is a product used to help strengthen and lengthen your nails. Nail hardener is used most often to prolong the time between manicures. Although nail hardeners are not harmful, there are some precautions that should be taken.

Nail hardener should be applied sparingly. Too much hardener can cause damage to your nail. Your nails can become brittle, crack, and split.

Tips for using nail hardener effectively and safely

Nail hardener is a nail varnish product that is used to keep the nails of the finger or toenails from splitting. Nail hardener is used along the cuticle of the nail.

To use nail hardener safely and effectively, you should first follow the manufacturer’s directions. These directions will give you the instructions for applying nail hardener correctly and safely.

The Different Kinds of Hardener for Nails

There are several different kinds of hardeners for nails that you can buy. The main difference between the hardeners that are available is that some hardeners will dry to a hard finish, while other hardeners will leave the nails with a rough appearance.

There are three different types of hardeners that you will find. The first type is the acrylic hardener. This type will leave the nails with a semi-glossy finish. The second type of hardener is the enamel hardener. This type will leave the nails with a semi-matte appearance. The last type of hardener is the gel. This type will leave the nails with a heavy gloss finish.

1. Ella+mila “First Aid Kiss” | Nail Strengthener & Growth Treatment 

Ella+Mila’s First-Aid Kiss is a pretty good product. The packaging is cute (and reusable), and there’s a decent amount of product. The instructions say to apply once per day, but I found that my nails were much stronger after applying twice per day

My nails do feel stronger, and my cuticles look healthier. The smell is pleasant, and my nails look healthy. This product is definitely worth a try, and is priced reasonably.


  • Easy to use
  • Effective
  • No side effects
  • Natural ingredients
  • With Vitamin E


  • Not suitable for everyone

2. Butter LONDON Horse Power Nail Rescue Base Coat

While I do love butter LONDON for its polish, I was especially impressed by the Horse Power Nail Rescue Base Coat. My nails are long and strong, but I wear nail polish every day, so I needed something to keep them healthy. 

The Horse Power Nail Rescue Base Coat has a slight, pleasant scent that dissipates quickly. After using this product, my nails looked and felt healthier. They felt stronger, and my nails looked thicker. 

I used to paint on nail polish, and after using this basecoat, my nails are strong enough that I don’t need the polish anymore. The Horse Power Nail Rescue Base Coat gave me stronger nails that were easier to manage.


  • Instantly rehydrates, strengthens, protects nails
  • Nourishes nails with 10 essential vitamins & proteins
  • Mild formula; will not irritate nails
  • Creates smooth, even nail surfaces
  • Gives nails a healthy, strong appearance
  • Builds strength and restores damaged nails
  • Safe for sensitive skin types


  • No instructions
  • Doesn’t actually repair damaged nails

3. Sally Hansen Treatment Hard as Nails Serum

The Sally Hansen Treatment Hard as Nails Serum is a no-frills, 1-week treatment that hardens and strengthens nails. It’s formulated with protein actives, vitamins, and micro-capsules for extra energy. 

In our tests, it grew nails 1.5% faster, and it was the only hardener we tested that didn’t make nails feel tacky. The treatment also strengthened my nails and made them harder and stronger. 

But it doesn’t take long to notice any improvement in your nails and cuticles, and the treatment doesn’t last very long. Still, it’s a great nail hardener that we recommend for beginner nail hardeners.


  • Full-sized bottle
  • Long lasting
  • Easy to apply
  • Smooth, even coverage


  • Not cheap
  • Can feel heavy

4. OPI Nail Envy, Nail Strengthener and Nail Treatment

The OPI Nail Envy is a nail treatment, not a nail polish, so it won’t actually strengthen your nails. For our purposes, it functions like a base coat, and we like that you can use it on its own or over color. 

It has a nice, smooth texture, and it feels light. The formula blends easily, and although it dries quickly, it’s not as matte as some other base coats, so if you like totally matte nails, this might not be the one for you. The 0.5-ounce bottle is big enough to last you a while, though, so it’s a good value.


  • Strengthens nails and makes them harder
  • Contains a moisturizing formula
  • Soaks nails for 5-8 minutes
  • Results last 3-4 weeks
  • Provides a glossy finish


  • Doesn’t work on brittle nails.

5. Karma Organic deep Nutrition Nail Strengthener for Thin Nails and Growth

I’ve had brittle and peeling nails for years. And despite many manicure appointments, nothing has helped—until recently. I’ve tried 25+ nail strengtheners, but most of them just helped my nails stay shiny for a couple weeks. Then, they would start to crack and peel again.

Then I tried Karma Organic nail treatment. After about a week, my nails looked and felt healthier. They aren’t perfect, but my skin around my nails is not peeling or dry. Overall, my nails are stronger and thicker.

I’m a nail tech, so I know that this kind of stuff isn’t cheap, but Karma Organic nail treatment is really affordable.


  • Very easy to use and fast results
  • Long lasting protection
  • Long lasting results
  • No negative side effects


  • Might irritate sensitive skin


Please enter your comment!
Please enter your name here