Kérastase Elixir Ultime Hydrating Hair Oil

Not when dosed correctly — this is the result we tested most rigorously, because weighed-down fine hair is the most common failure mode of hair oils. At 1–2 pumps on damp ends, our fine-hair tester reported zero flatness or greasy buildup, even with daily use across a full week.

The key is dosage discipline: start with one pump, focus on mid-lengths and ends only, and avoid the roots. Fine-hair users who over-apply (3+ pumps) will see some weight, just as with any hair oil. If you have very fine or thin hair and have avoided hair oils for this reason, Elixir Ultime is one of the lighter options we've tested.

Yes — fully safe for colour-treated, highlighted, bleached, keratin-treated, and chemically straightened hair. The oil sits on the hair shaft as a finishing and protective layer; it does not interfere with colour molecules or chemical treatment bonds. Our colour-treated tester used it for 8 weeks without any visible colour fading attributable to the product.

Kérastase specifically positions Elixir Ultime as a protective finishing step for colour-treated hair, since the heat-protection function helps shield colour-treated strands from additional damage during styling, which is one of the leading causes of colour fade over time.

The most important step most users skip is warming the oil between your palms before application. Dispense 1–4 pumps (depending on hair length and thickness) into your hands, rub your palms together to warm the oil, then run your fingers through the lengths of your hair first — where hair is driest — before working upward, stopping 1–2 inches from the scalp. Avoid applying directly to the scalp unless using it as a pre-shampoo treatment.

A pro tip from our tester: for heat protection, apply to damp hair before blow-drying rather than after — the oil needs to be distributed before heat styling to provide its protective benefit. For a pure shine finish on already-styled hair, apply a small amount (half a pump) to dry hair as a final step.

Yes, if you're a repeat user. The refill pouch costs $54 versus $62 for a brand-new bottle — a modest discount, but the larger benefit is sustainability: the pouch is made with 95% recycled plastic, and reusing the same glass bottle (itself made with 30% recycled glass) reduces packaging waste meaningfully if you go through multiple bottles per year.

Refilling is simple: unscrew the empty insert, remove it from the glass bottle, insert the new refill, and twist to lock it in place. The main limitation is availability — refill pouches are currently best stocked direct from Kérastase or at Sephora, with patchier availability at other retailers.

Buy Kérastase Elixir Ultime if: you want maximum shine payoff, prefer a refillable and more sustainable package, or want a versatile oil that also performs as a heat protectant for everyday styling. It also offers more product per bottle at 75ml vs Olaplex's 30ml.

Buy Olaplex No. 7 if: your hair is significantly damaged or over-processed and you want a bonding-focused treatment alongside shine, or you're already using other Olaplex bond-building products and want a matching system. For most users prioritising shine and everyday versatility, we recommend Elixir Ultime without hesitation. Try the $29 travel size from Kérastase direct before committing to full size.