Isdin Si-Nails Nail Strengthener review

My nails have been fucked up for quite some time. There isn’t really another term for it. I heard that Isdin’s nail hardener is good – but is it? Here’s my Isdin Si-Nails Nail Strengthener review.

I never had the strongest nails, but through care they’ve been manageable. Lately? Not so much. They were peeling off in layers, and for over three months, I had the same split developing at the same place on my pointer finger’s nail. Every time I had managed to grow it out, it would split again, and one morning, after removing my nail polish, I looked at my nails and just had enough. In came Isdin’s Nail Strengthener, after I had read glowing reviews.

What is it

I’ve used various nail strengtheners before, and they’re all garbage apart from Miracle Nails. Microcell and all those hardening basecoats? Forget it.

I’m personally naturally adverse to supplements (I used to work in the industry), but here’s the part of the post where I have to stress that brittle nails can be a symptom for underlying health problems. Do ask a doctor when you have long-term problems!

While other nail hardeners usually come in form of a lacquer, this one isn’t. Applied with a brush, this is a watery formula that’s completely absorbed by your nails in no time.

“ISDIN Si-Nails is an innovative nail growth formula that has been clinically proven to strengthen brittle nails by increasing thickness, density, and durability of the nail and cuticle. Visible results in just 14 days.”

Isdin

Ingredients

Water, Alcohol Denat., PEG-40 Hydrogenated Castor Oil, Butylene Glycol, Acrylates Copolymer, Silanediol Salicylate, Tromethamine, Caprylic/Capric Triglyceride, Hydroxypropyltrimonium Hyaluronate, Triethanolamine, Biosaccharide Gum-2, Pistacia Lentiscus (Mastic) Gum, Propylene Glycol, Phenoxyethanol, Benzyl Alcohol, Methylparaben

Isdin

I guess the high alcohol amount is due to its function of a penetration enhancer. The only ingredient standing out is the cationic hyaluronic acid. Remember that one? I encountered it a lot lately: in haircare and in a face wash. In those products – and in this one! – it’s designed to adhere to a surface to protect and strengthen.

Polymers, silicium and mastic gum are usual ingredients in nail strengtheners: they promote not only nail growth (mastic gum), but also coat the nail and make it stronger.

Formula

Cuticle care is the most important thing when you want stronger nails. Like hair, nails are made of keratin. Like hair, nails are made with dead, compacted cells. The nail matrix (between your first knuckle and your cuticles) is the area where your nail is growing, so taking care of that area is the most important part of nail care.

That means nail hardener works a bit like conditioner: it can make your nails look and feel nicer, but it won’t make them grow differently.

The pen Isdin’s nail strengthener comes in has plastic bristles and has a serum-like texture. The site tells you to click 25 times when you first open it – I needed to click quite a few times more. Per Isdin, you need one click per application, and I do find that a bit finicky. First, one click doesn’t release any serum for me, and then, it’s too much for one nail. (Even when you coat the underside of the nail as possible.)

Application

You’re supposed to click the pen to activate the mechanism. Then coat the side of your nails first, then the middle and then the undersides as far as possible.

You should do that daily, and to prevent contact with water afterwards – sadly, the site doesn’t state for how long. You can’t apply it over nail polish, and should see the first effects after two weeks. Sadly, too, the site doesn’t tell you for how long exactly you’re supposed to use the pen. I used it daily for two weeks, and then every other day because my nails started to hurt after application. I took that for a sign that they were becoming sensitized to either the alcohol or other ingredients.

Also, I moisturized the shit out of my nails in the time I used it, mainly with Paula’s Choice’s lip and body treatment balm.

Effect

As a die-hard nail polish user, you can imagine how odd it was for me not to have polished nails. I can tell you: I hated every single second of it during the first week. The reason for that was that usually, nail polish stabilizes my nails and makes them more durable. Without it, I felt like my rough and peely nails would snag and catch on everything: towels, clothes, and even hair, and then break off and look even worse. Also, I do polish my nails because I’m a cuticle picker, and I don’t do that when I’ve just polished my nails. So, I didn’t have that crutch, and yes, my cuticles and nail beds have suffered in those three weeks.

I started to baby my nails and apply nail balm, hand cream religiously and also file them down as much as I could to minimize further breakage.

Effect over time

After one week, though, they seemed to get stronger and less peely:  could still see points were nails potentially could break off, but miraculously they didn’t. And, then, miraculously, after one week the annoying split in the nail of my pointer finger didn’t split further.

After two weeks, it was gone, while my nails grew madly.

As I write this, it’s three weeks and three days after I first started to use the pen, and nothing has changed since the end of the first week: I can still see points where peeling could occur – but doesn’t. My nails seem a bit smoother and shinier, grow like weeds, and haven’t broken off in days.

Isdin Nail Strengthener review: Worth it?

While there’s undoubtedly some effect going on, there’s so much I don’t like in this product: first, the click mechanism is annoying as always. Honestly, I haven’t met a click mechanism that works properly yet.

Second, for nail polish lovers like me, not being able to use a polish is more than annoying. I vastly, VASTLY prefer a product that I can use underneath a regular polish.

Third, I do find the brand’s instructions rather vague when it comes to the recommended timeframe: “Visible results may be seen in 14 days, with best results achieved from ongoing application.” What the heck is “ongoing application” supposed to mean?!

For myself, I’ll go on using it in between nail polish applications as part of my manicure. I’m curious to see what happens with those nails that still have visible peely layers. Will they grow out? Will they break off again?

And finally, I’ve definitely pampered my nails during those three weeks – I can’t exclude effects from that in my final conclusion. Especially PC’s lip and body balm is supposed to strengthen nails over time – so maybe there’s some effect from this as well.

I’m coming out of this trial with undoubtedly better nails, but found the whole process annoying. Also, the pen is incredibly expensive (if you’re in Europe, look at online pharmacies for the best deals).

Availability & Price

2.5ml are $32 on their website. I bought mine at an online pharmacy for around 24€.

Please note that this post is not sponsored in any way. We buy products ourselves, with our own money, and don’t accept exchanging goods or money for reviews. We are completely independent, and our reviews reflect that.