If you take one thing from our aftercare advice, make it this: switch to a sulfate-free shampoo. It's the single biggest factor in how long a keratin or smoothing treatment lasts, and it's gentler on frizzy, coloured and dry hair too. Here's how to pick a good one.
Why it matters
Sulfates (usually sodium lauryl sulfate / SLS or sodium laureth sulfate / SLES) are powerful detergents that create that satisfying lather — but they're harsh. They strip natural oils and, crucially, strip keratin and smoothing treatments out faster, so your frizz-free result fades sooner. A sulfate-free shampoo cleans gently and protects both the treatment and your hair's moisture. (More in our keratin aftercare guide.)
How to choose a sulfate-free shampoo
Look for:
- No sulfates — check the label for SLS, SLES and other "…sulfate" ingredients.
- No sodium chloride (salt) if possible — salt can also strip keratin.
- Moisturising ingredients — glycerin, panthenol, natural oils, amino acids.
- No harsh drying alcohols high in the ingredient list.
- Colour-safe if your hair is coloured.
- Matched to your hair — richer for dry/curly hair, lighter for fine hair.
What to look for by hair type
| Your hair | Prioritise |
|---|---|
| Keratin / smoothing-treated | Sulfate-free and salt-free, gentle cleansing |
| Coloured | Sulfate-free + colour-protecting |
| Dry / curly | Sulfate-free + extra moisture (oils, butters) |
| Fine | Sulfate-free but lightweight, no heavy silicones |
Our specialist picks
- Salon favourite — Olaplex Nº.4 Bond Maintenance: the gold-standard sulfate-free shampoo for keratin-treated, coloured and damaged hair.
- Also salon-grade — Redken Acidic Bonding Concentrate: strengthens the hair's bonds while it gently cleanses.
- Made for keratin — NYK1 Salt & Sulphate-Free: formulated specifically as keratin and extension aftercare.
- Budget pick — OGX Argan Oil of Morocco: gentle, sulfate-free and great value.
Make it go further
A sulfate-free shampoo works best alongside the rest of a gentle routine: condition every wash, use a weekly mask, wash only 2–3 times a week, and always use heat protection. If you're keratin-treated, this routine is what gets you the full 3–6 months — see is keratin good for your hair? and the keratin treatment page.
Booked in with us? We'll recommend the right aftercare for your exact treatment — just ask, or get in touch.
