KÉRASTASE Heat-Protecting Leave-In Cream Extentioniste Thermique — Strengthens, Seals Split Ends, 450°F Shield

KÉRASTASE Resistance Extentioniste Thermique is a leave-in, heat-protecting cream that reinforces weakened mid-lengths and ends while sealing split ends for smoother, stronger hair.

This lightweight primer is designed to be applied to damp hair before blow-drying or heat styling. It combines a targeted amino-acid derivative with ceramides and taurine to support fiber resilience, improve manageability, and create a thermal shield up to 450°F. Use it as part of the Resistance Extentioniste routine to reduce breakage and help hair reach healthier lengths.

How does this primer protect hair during heat styling?

The formula forms a protective barrier that reduces mechanical and thermal stress when blow-drying or using hot tools. Rather than masking damage, it helps strengthen the fiber while limiting further breakage during styling.

• Thermo-protection rated to 450°F to defend against heat exposure.
• Lightweight cream spreads evenly on mid-lengths and ends without weighing hair down.
• Seals split ends to reduce friction and breakage during combing and styling.

What ingredients reinforce hair structure and why do they matter?

Key actives work together to bolster the hair’s internal structure and surface. Creatine R (an amino-acid based complex) supports fiber integrity, while ceramides restore surface cohesion and taurine contributes to resilience.

• Creatine R: supports internal fiber reinforcement for reduced breakage.
• Ceramides: improve cuticle cohesion and enhance shine.
• Taurine: helps maintain elasticity and moisture balance along lengths.

How should I use Extentioniste Thermique for best results?

Work a quarter-sized amount through towel-dried hair, concentrating on mid-lengths and ends where damage is most common. Follow with blow-drying or thermal styling as desired; regular use with the Extentioniste shampoo and conditioner maximizes strengthening benefits.

• Apply to damp hair—do not rinse out.
• Focus product from mid-length to ends, avoiding the roots for lightness.
• Use alongside Extentioniste shampoo and conditioner for a complete regimen.

Will this product help with split ends and everyday breakage?

Extentioniste Thermique helps to temporarily seal split ends and reduce immediate breakage during styling, making hair appear smoother and less prone to snap. It supports longer-term strength when used consistently with the Resistance collection but does not replace trimming for advanced split ends.

• Seals and smooths split ends to reduce visible fraying.
• Decreases breakage from blow-drying by up to 90% in controlled tests when used as directed.*
• Improves manageability and shine between salon cuts.

Who is this for: KÉRASTASE Resistance Extentioniste Thermique is formulated for weakened hair that struggles to retain length—ideal for anyone with mid-length damage, frequent heat styling, or visible split ends who wants a protective, strengthening leave-in primer. It suits most hair types except those needing oil-heavy care at the roots; use sparingly near the scalp to avoid weighing fine hair down.

Ingredients

Water, Isopropyl Myristate, Dimethicone, Triethanolamine, Amodimethicone, Phenoxyethanol, Carbomer, Polyquaternium-4, Potato Starch Modified, Hydroxypropyl Guar, Behentrimonium Chloride, Trideceth-6, Amyl Cinnamal, Hexyl Cinnamal, Isopropyl Alcohol, Benzyl Alcohol, Linalool, Hydroxycitronellal, Cetrimonium Chloride, Citronellol, Limonene, Benzyl Cinnamate, Creatine, 2-Oleamido-1,3-Octadecanediol, Taurine, Parfum, Fragrance.