ISDIN Si-Nails Strengthening & Hardening Nail Serum Treatment, 0.08 fl oz

I wish I had thought to take "before" pics for this review. For years, my nails have been an embarrassment. The nails were brittle and would just rip apart if they grew past my nail bed. The top layer would peal back. If I was out with a group of people I would try to keep my fingers hidden. Sometimes, I notice women looking at them. Ugh, what an embarrassment. I finally went to a dermatologist who ran some tests. Results... my body is no longer storing "zinc", which promotes strong nails and hair growth. She immediately recommended this product. After using one pen, you can see in the pics that my nails look pretty healthy and are growing again. I'm so relieved that I just needed to write this review. If you are experiencing these types of issues with your nails, see your doctor, but also, give this product a try!

This stuff was literally an answer to prayer! HIGHLY RECOMMEND! I had been struggling with thin, peeling nails for over a year. I had back-to-back surgeries and my dermatologist told me my damaged nails were probably a result of the anesthesia. (I've never done regular manicures and very rarely polish or gel, so I couldn't blame that.) My nails were so thin they hurt and they would continually split and peel no matter how much I used nail strengthening treatments or polishes. I was at my wits end and tried ordering ISDIN as a last resort. I thought it was a little expensive at the time, but now I believe it was worth every penny! I keep an extra tube on hand now so I never run out. The product and brush are so easy to use. In the beginning I applied it twice a day but tried to keep using it at least once a day for two months. Now that my nails have improved I use it about every 1-2 days. The product is easy to apply and dries and disappears very quickly. I was worried it would be messy and sticky but it is not at all. Sometimes it takes one click per nail to get it going, but sometimes one click will treat a few fingers. A little goes a long way and you will get the feel of it. The product does take time to work. It was 2 months before I had a complete nail grow out without peeling. They are strong now but I am still careful to not use my nails as "tools" so that I don't break them. I still have a split on my thumbnail but I believe it will grow out as long as I am careful and keep applying the product every few days. I will say my nails are a little "ridged" and I don't know if that's just my nails or a result of the product, but it is a small price to pay for strong nails and I can just buff them down smooth. The photos you see are: 1. at the beginning of use, 2. after 6 weeks of using the product, and 3. at 2 1/2 months (they do grow longer but I like to keep them short) Don't hesitate! Buy this product!

I’m having to update my review because despite only getting to use it twice because the product packaging is super faulty, it works! I have been struggling to repair my nails for YEARS, and they are strong and grown out again instead of delaminating. Also, a split I haven’t been able to grow past in 4 years on my thumb nail is healed. It’s stupid expensive if you only get two uses out of it like I did, but I’d buy it again if my nails start showing the same issues because it is the only thing to have worked! The button to click gets stuck constantly, so trying to use this is basically a workout for your thumbs. For such a high price, I’d expect it to function better. I’ve only been able to successfully use it twice, with a ton of effort and time to get the button to click correctly. Can’t say if it works on nails, because I can’t get it to function well enough to use it.

I have had a split thumbnail (vertical split below the quick) for many many months and I’ve been keeping it cut really short and the supergluing it so it isn’t get caught on things. As it grew out, it would still stay split. I tried all the supplements and vitamins and nothing g was helping. My dermatologist recommended that I try this and it worked! Within a few weeks of applying most days the nail has grown out with no more split! Such a huge relief as I had been dealing with it for so long I was afraid it was never going to go away. This pen has lasted me over a month.

I have waited four months to write this review because it just seemed too good to be true. But it is true. I am a senior citizen who suddenly found all my nails chipping, cracking, and splitting. I thought about posting a "before" picture, but they looked too awful. I used to try to hide my hands when in public. I tried nine months of biotin capsules, and no results. I found a recommendation from other users online of the ISDN product. When I started using it, I was completely skeptical. The product is clear, thin, and more like water than anything else. I could not see how this could work. It took six to eight weeks before I began to see genuine results - tiny 1/8" nails taking the place of nails that looked like they had been chewed off by rats. Now, five months on, I have 1/4" normal-looking nails that make me happy every day. I have to file them to keep from getting too long, but not in order to even out breakage. They don't seem to chip or break at all under normal use. I actually took the ISDIN box to show my doctor. She said they often have people ask for help with breaking nails, and they never have anything to suggest. She took down the info about this product. For me, a container lasts about two months or longer. I have noticed that the applicator doesn't always work the way the instructions say. Often I get enough product from one "click" to do a whole hand. Other times, the applicator needs to be primed several times. But I don't care as long as it works SO well. Reading over my review, it looks like someone paid me to write it! It's all true.

I could see a difference in a matter of days

Does it help ? Yes, but not $39 worth. If it was cheaper I would buy again. After 4 months they look better, yes, but not by much.

I’m very particular about what I use on my nails, especially when something is marketed as a “treatment” or “serum.” This works—but not in the way the name suggests. If you look at the ingredient list, this is not really a nail health or repair serum in the true sense. You’re not getting ingredients that meaningfully support nail growth or structural repair at a deeper level. What you are getting is a formula built more for surface improvement. There’s a high amount of alcohol, which helps it dry quickly and gives that immediate, lightweight feel. You also have film-forming ingredients like acrylates copolymer that create a smooth coating over the nail. That’s what gives the appearance of smoother, more uniform nails. There are some hydrating components like hyaluronic acid derivatives and glycols, but in this type of formula, they’re functioning more for temporary conditioning rather than long-term repair. The mastic gum is interesting—it’s sometimes used for tightening and refining effects—but again, this is more about surface appearance than actual nail health. So what does it do well? It smooths the look of the nail, gives a more polished appearance, and can make nails feel a bit more reinforced temporarily. It’s more like a cosmetic finisher than a treatment. Application is easy. The brush pen format is convenient and intuitive, and it absorbs quickly without leaving residue. It’s simple to work into a routine. But from a value standpoint, I don’t think it justifies the price. There are less expensive options that are better formulated for actual nail strengthening and repair—especially if you’re looking for long-term improvement rather than a temporary smoothing effect. That distinction matters. If you go in expecting stronger, healthier nails over time, this may disappoint. If you think of it as a quick, cosmetic smoother, it makes more sense. Overall, it’s fine. It does what it does—but for me, it doesn’t stand out enough to justify the cost.

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Lamentablemente me queme las uñas debido a una reacción alérgica al gelish 😢 lo adquirí para empezar a cuidar mis uñas naturales de nuevo y es una verdadera joya, están creciendo bastante, súper fuertes y sanas y sin romperse ninguna 🤩 recomiendo totalmente

Espectacular producto

Me gusta este producto, ayuda mucho al crecimiento de las uñas, en mi caso si ayuda a que crezcan pero se me siguen rompiendo :(

Me está dando buen resultado