Leave-In

The question we get most often about this category is whether a leave-in replaces your conditioner. It doesn't, and getting that wrong is why some people decide leave-ins "don't work" for them. Conditioner does its job in the shower and gets rinsed away. A leave-in stays on and keeps doing the job all day, which is also where heat protection, curl definition and frizz control actually live.

The format is the decision, not the brand

Almost everyone shops this category by brand and then wonders why the product feels wrong. The thing that matters is how much weight your hair can carry. Thick, coarse or curly hair takes a cream — GK Hair Global Keratin or L'Oréal Curl Expression. Normal to thick hair usually does best with a milk like Kérastase Nutritive Nectar Thermique. If your hair goes flat easily, skip both and use a spray, something like Kérastase Discipline Fluidissime or Revlon UniQ One. Serums and oils are for ends only, whatever your hair type. And leave-in masks are a treatment rather than a daily step.

Curly hair: the timing matters more than the product

Curls need a leave-in more than any other hair type, but the most common mistake isn't the product, it's applying it to towel-dried hair. Put it on hair that's still dripping, scrunch, and then leave it alone — combing it through afterwards is what breaks the clumps you just formed. Plumpy Curls Detangling Primer, L'Oréal Curl Expression, Cantu and Mielle all work here. More in Curl Enhancement.

K18, Olaplex and Redken leave-ins aren't the same thing

K18 is a peptide treatment you leave in and don't rinse, and it's meant for hair that has been bleached or coloured repeatedly — you use it for a stretch, not forever. Olaplex N6 Bond Smoother is closer to a daily styling cream that happens to have bond chemistry in it. Redken Acidic Bonding Concentrate Leave-In sits between the two and is the easiest to just add to an existing routine. If your hair isn't chemically damaged, none of these will feel worth the money compared with a good cream. See Damage Repair.

Heat protection: read the bottle

Not every leave-in protects against heat, and plenty of people assume theirs does. If you blow-dry or straighten, pick one that says so: the Kérastase "Thermique" range, L'Oréal Pro Longer 10-in-1, or Redken Acidic Color Gloss Heat Protection. See Heat-Damage Protection and, for humidity rather than heat, Frizz Control — Blumin Kaktus Goodbye Frizz and Color Wow Dream Coconut are the ones people come back for.

Coloured, fine, coarse

Coloured hair: L'Oréal Vitamino Color 10-in-1, and see Color Protection. Fine hair: sprays only, and keep everything off the roots. Coarse hair: go heavier than you think you need. Lazy Republic sells separate Fine and Coarse editions, which is a genuinely useful shortcut if you'd rather not guess.

Questions people actually ask

Do I still need a regular conditioner?

Almost always yes. Very fine hair is the one real exception, where a leave-in on its own can be enough.

Wet hair or dry hair?

Damp for most hair, dripping wet for curls. On fully dry hair a leave-in tends to sit on top and look greasy — that's a job for a light spray or a few drops of serum instead.

How much should I use?

Less than you'd think, and never near the scalp. Mid-lengths and ends, then add more only if it still feels rough once dry.

Can a leave-in make hair greasy?

Yes, and it's usually one of three things: too much product, the wrong format for your hair weight, or applying it too close to the roots. Same product, different placement, different result.

Every day or only after washing?

After washing is the default. A light spray in between is fine on curly or dry hair, but daily cream on fine hair will weigh it down within a few days.

Is a leave-in the same as a hair serum?

Not quite. A leave-in is about moisture and manageability through the length; a serum is a smaller amount on the ends for shine and heat. Plenty of people use both.

Not sure which format suits your hair? Our team can help. Or start with Kérastase Nutritive Nectar Thermique and browse more in Haircare.