Fourteen-year-olds using adult serums: an aesthetic doctor says teenagers don't need retinol and it can leave dark spots

They're called "Sephora Kids" - teenagers of around 14 who buy and use cosmetics meant for adults. The trend isn't only expensive, and it doesn't only create an emotional dependence on the shelves. Products that aren't formulated for young skin can do it real harm, warns Dr Scarlett Alvarado, a specialist in aesthetic medicine who works with the teen cosmetics firm 4Teens.

When should you start? There's no fixed age. Two steps can begin in childhood: sun protection during the day and cleansing the face in the evening. Sunscreen is the first product to buy - and it goes on even when it's cloudy or raining.

During puberty, skin can become oily, dry or prone to acne. Acne is the most common worry, and the marks and scars it leaves concern many teenagers - boys and girls alike. The routine should be simple and tailored: in the morning a moisturiser suited to the skin type, then sun protection. In the evening thorough cleansing and, if needed, a targeted treatment - salicylic acid for acne, for example, with professional advice. Dry skin may need nothing more than a moisturiser.

Among ingredients, useful ones include salicylic acid, postbiotics, certain ferments and niacinamide, which is gentle and suits oily skin, visible pores and minor imperfections.

What should stay on the shelf for now

Retinol, vitamin C and glycolic acid are not recommended for regular use in teen routines. Retinol, according to Alvarado, isn't needed for young skin, certainly not for cosmetic or anti-ageing purposes. Its exfoliating effect can disrupt the skin barrier or cause hyperpigmentation - exactly the dark spots young people are afraid of. Retinoids have a place only in specific cases of acne, under medical supervision.

A fourteen-year-old with an anti-ageing serum is a picture that says more about marketing than about skin. And yes, the advice comes from a doctor who works with a teen cosmetics brand - but the message "fewer products, more sunscreen" is hardly a sales trick.