Anyone who has ever stepped out of the shower and grabbed a brush knows the warning - do not comb wet hair, it will snap. And then you walk into a salon, they detangle your hair while it is still dripping, and nothing happens. So who is lying?

Nobody. The difference is not in whether, but in how.

What exactly happens inside the hair

When hair is wet, the strand swells and becomes more elastic, but at the same time more vulnerable to tension and friction. Pharmacist Elvira Mateos of the Mateos Cáceres pharmacy explains it like this: "Combing wet hair can damage it because when the strands are wet they tend to swell, and swollen hair breaks more easily. On top of that, it contributes to frizz."

Juan Leal, education director at Pierino Cosmetics, puts the problem exactly where it belongs: "In that state, the strand is more elastic but also more brittle. If we apply tension or friction, we create micro-fractures that accumulate over time." The key word is accumulate. It is not about one combing - the damage is done by repetition.

Eighty percent, not one hundred

Should you wait for hair to dry? Yes, but not literally all the way. Mateos recommends waiting until the hair is about 80 percent dry before using certain styling tools - by then the strand has recovered part of its resilience.

But if you have to detangle while it is still very wet, then two things apply: a product that provides slip, and the right tool. And there is the explanation for why hairdressers work on wet hair without consequences. A leave-in product or a detangling spray reduces the friction between the hair and the tool. "These products help smooth the cuticle, reduce friction and let the brush glide more easily without pulling," Mateos says.

The mistake almost everyone makes

According to Mateos, the most common mistake is putting the brush at the root and pulling down to the ends - which gathers every knot in one place. The correct technique is the reverse: start at the ends and work gradually toward the mid-lengths and the root. "Hair should be combed slowly and gently from the ends working toward the scalp to prevent breakage. That way the knots dissolve gradually without creating excessive tension on the strands."

So the conclusion is less absolute than the headlines sound. You do not have to banish the brush from the bathroom for good. If you use a product that gives slip, choose the right tool and detangle without pulling, you can work with damp hair. What is being avoided is the combination of water, friction and force on a strand that is at its most vulnerable at that moment.

Or as Leal puts it: "The real problem lies in what we do every day without noticing." Small movements, repeated often enough, become visible damage - and that is not a sentence that applies only to hair.