ISDIN Si-Nails Nail Strengthening Serum 0.08 fl oz — Fast-Absorbing, Hydrating Hardener for Thin Brittle Nails

ISDIN Si-Nails is a fast-absorbing nail strengthening and hardening serum designed to build durability, reduce brittleness, and visibly improve the look of thin nails.

Formulated in Spain, this concentrated 0.08 fl oz treatment targets weak or damaged nails with a blend of silicon-promoting and hydrating ingredients. Its fast-drying, non-greasy texture lets you add a reinforcing layer to your nails without long wait times, while ongoing use helps restore firmness and smoothness. Clinically tested to increase nail strength and reduce roughness, Si-Nails is intended for regular at-home use as part of a nail care routine.

How does Si-Nails make fragile nails stronger?

Si-Nails uses silanediol salicylate to encourage silicon presence in the nail structure, supporting natural rigidity. The formula also contains pistacia lentiscus gum to support keratin, which is essential for resilient nails. Together these actives reinforce the nail matrix and reduce splitting.

• Silicon-promoting silanediol salicylate strengthens the nail plate
• Pistacia lentiscus gum supports keratin production for structure
• Regular application improves resistance to peeling and breaking

Will this serum hydrate cuticles and improve nail texture?

Yes — Si-Nails includes cationic hyaluronic acid, an enhanced form of hyaluronic acid designed for better adhesion to the nail and surrounding skin. This ingredient helps retain moisture at the cuticle and nail surface, smoothing roughness and improving flexibility. Over weeks of use, nails appear less dry and more uniform in texture.

• Cationic hyaluronic acid delivers targeted moisturization to cuticles
• Reduces surface roughness for a smoother nail finish
• Improves flexibility to lower the risk of cracks from dryness

How quickly will I notice results and how should I apply it?

Users have reported visible improvements in hardness, hydration and reduced brittleness after about 28 days of regular use. Application is simple: apply a thin coat to clean, dry nails and allow it to dry; no buffing is necessary. Use as directed — typically once daily — to build and maintain results.

• Apply a thin layer to clean, dry nails and cuticles
• Allow to dry fully before touching surfaces or applying polish
• Daily use produces the best cumulative improvement after several weeks

Is Si-Nails safe for nails with frequent polish or salon treatments?

Si-Nails is formulated to complement regular polish use and professional services, acting as a protective and restorative base layer. Because it dries quickly and absorbs well, it can be used under nail polish or between salon treatments to help reduce damage and support recovery. If you use harsh acetone removers often, pairing this serum with gentler removal methods will help maintain benefits.

• Works as a base layer under nail polish
• Fast absorption reduces interference with manicures
• Supports recovery after frequent salon procedures

Who is this for: ISDIN Si-Nails is suited for anyone with thin, brittle, or rough nails who wants a compact, fast-absorbing booster to increase nail durability and hydration. It's a practical option for frequent polish wearers, people exposed to detergents or water often, and anyone seeking to restore a smoother, harder nail appearance without lengthy salon visits.

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