‘Miracle in a bottle’ nail strengthener ‘grows them in 10 days’ for under £15

The nail strengthener is available in six different shades.

Growing long and strong nails can sometimes feel like an uphill battle – which is why some are turning to a nail strengthener one shopper described as making a ‘major difference’ to their ‘awfully fragile’ nails. Now, the OPI Nail Envy Strengthener has had an upgrade – with a new vegan formula and different colours to choose from.

The strengthener is currently priced at £14.72, down from £23, on the OPI website, thanks to the code treat20 – which can be used until June 23 at 11:59pm. One of its most popular colours is the OPI Classic shade, which gives a sheer, shiny effect. It’s available in eight further colours: a sparkly midnight blue, white, red, beige, dark pink, maroon, and two options for sheer pink shades. At the heart of the formula is Tri-Flex Technology, which forms a liquid shield over the nail to build strength layer by layer.

Combined with biotin, calcium, and vitamins A, C and E, the treatment is designed to help protect against chipping, peeling and splitting while supporting overall nail health. The routine is designed to be simple and consistent: apply two coats on day one, then one coat daily for five days, before removing and repeating the cycle.

For best results, it can also be paired with Repair Mode as part of a full nail care routine. According to OPI, nails can become up to 95% stronger in just one week of continued use, making it a popular option for those looking to improve nail condition over time without overcomplicating their routine.

With its updated vegan formula, expanded colour range and science-led approach, Nail Envy continues to be a go-to strengthener for anyone wanting healthier-looking nails. As an alternative option, Lookfantastic has the Mavala Scientifique K+ Nail Hardener for £21.

This is said to be a unique nail hardener that is designed to visibly strengthen weakened nails over time. A cheaper alternative is the Boots Nail Strengthener 10ml for £6. This one is ideal for dry, dull and weakened nails, and leaves a long lasting glossy finish.

Buyers have rated the OPI Nail Envy Strengthener highly on the website. One person said: “I have been using this for a month now because of the rave reviews! It’s a freaking miracle in a bottle. I used the Seche Vite Fortified Nail Strengthener before this and was VERY disappointed. But Nail Envy is amazing! I’m so impressed by how well it actually works. My nails no longer bend like paper. What a marvellous product! This is the longest my nails have been in years and they haven’t broken AT ALL, compared to breaks every few days without it. I follow the directions exactly: 2 coats on day one, then one coat every other day for a week, remove and repeat.”

Another added: “This nail strengthener does exactly what you’re hoping it would do. It not only provides a heavy layer of protection when doing any sort of task, but it acts like a shield so my nails don’t snap. The natural shade also looks great. It’s extremely easy to apply and dries remarkably fast. I highly recommend this product if you need a serious nail shield!”

Some did remove a star, with one person saying: “A great colour but not quite as good a finish as The Original Bubble Bath. Please bring it back.”

Overall, most people were pleased, for example this shopper said: “I have awfully fragile nails, but I noticed a major difference within a week of using this stuff. I had a severe peel on my middle finger from banging it on a metal fixture on Day 2. I just coated more Nail Envy over the raw edge. Within just a few days, the surface smoothed over completely and it looked like the peeling layers were literally fusing back together. By day 10, my nails were entirely flexible, shock-resistant, and just kept growing and growing.”

All colours of Nail Envy Strengthener are available from OPI with a discount, thanks to the code treat20.