Can this serum be applied to the scalp, or is it only for the lengths? — The Doctor. Maximum Energy Keratin, Arginine, and Biotin Hair Serum, 89 ml

The formula of this serum was designed from the outset for dual use: it is applied to the scalp and also spread along the lengths of the hair after washing. This is not a generic caveat but a deliberate feature of the formula: different ingredients work at different levels.

On the scalp, the key role is played by arginine, an amino acid included in root-zone products to support microcirculation and the supply of nutrients to the roots. The moisturising ingredients — urea, betaine and glycerin — also work there: they soften the skin and reduce the feeling of dryness that often accompanies weakened hair or hair you are actively growing.

Along the lengths, the main work is done by hydrolysed keratin: its molecules are small enough to spread over the surface of the hair and fill damaged areas of the cuticle. Visually, this gives a smoother, less frizzy strand that reflects light better. Biotin complements the formula, focusing it on reducing breakage.

The serum has a light, leave-in texture — it does not leave a greasy film, so applying it to the roots does not weigh down root volume. A convenient order: after washing and gently towel-drying, apply a small amount to the scalp, massage it in lightly, then spread the rest along the lengths, taking care not to overload the ends.

If your scalp tends to be sensitive or prone to irritation, start with a minimal amount and watch how it reacts over several applications.