Most conversations about hair skip the scalp completely. People will spend a fortune on masks and oils and bond builders and never once actually look at the skin the hair is growing out of, which is a bit mad when you think about it, because the scalp is skin. It has a barrier that can be stripped, oil glands, its own microbiome, and it gets irritated and inflamed just like the skin on your face does.
And the scalp is usually where the problem is. Somebody will tell me their hair has gone flat or dull or feels dry no matter what they put on it, and they've already been through five or six products looking for the answer in the wrong place. Meanwhile there's an itch, or a bit of flaking, or the roots are greasy again by the next morning, and none of that gets mentioned because we've all been taught to think of haircare and skincare as two separate categories.
Worth knowing what's actually going on under there. Every hair sits in a follicle, which is a little tube of skin reaching down into the dermis, and the hair itself is built at the very bottom of it from cells that divide faster than almost anything else in the body. They're fed by a tiny blood vessel, which is exactly why things like iron levels come into the conversation. By the time a hair pushes out through the surface it's already dead. It's keratin, there's no living tissue in it, and that's why nothing you put on the lengths repairs anything in any real sense. Everything that decides whether your hair comes in strong or weak or falls out early is happening a few millimetres down in the skin, and that's the part you can actually do something about.
Scalp skin is a little different to facial skin in a few ways that matter. It has the highest density of oil glands anywhere on the body, roughly a hundred thousand follicles, each with its own opening that can get blocked, and a resident yeast called Malassezia that lives there quite happily on all of us until the balance tips. The main difference though is that you can see your face. Your scalp is under a full head of hair, so realistically most people never look at it, and problems get ignored until they're impossible to ignore.
Flaking, itch, and the dandruff confusion
This is the area I get asked about most, and it's where the wrong assumption causes the most trouble.
A genuinely dry scalp gives you fine white flakes and a tight feeling, and it's usually something you've done to it. Water too hot, shampoo too harsh, washing constantly, a barrier that's been stripped one too many times. Dandruff looks different. Bigger flakes, often more yellowish and greasy than dry, usually with some redness and itch alongside it. It sits on the seborrhoeic dermatitis spectrum and it's driven by that Malassezia yeast feeding on the oil your scalp produces.
Which is why the instinct to oil a flaky scalp so often backfires. If what you have is dandruff, oil feeds the exact thing causing it. Dandruff needs an antifungal shampoo to actually treat it, so look for ketoconazole or zinc pyrithione, and if it keeps coming back or it's creeping down onto your face and ears then it's worth seeing your GP rather than working through another shelf of products.
Scalp psoriasis is a different thing again and it gets mistaken for stubborn dandruff all the time. The scale is thicker and more silvery, you can often feel raised plaques under your fingers, and it tends to have clear edges and sometimes extends past the hairline onto the forehead or behind the ears. Anti-dandruff shampoo won't shift it. That one needs a proper diagnosis and prescription treatment, and there's no point spending months on the wrong shampoo when a five minute look would sort it out.
Itch on its own, with no flaking, is usually irritation. Product residue that isn't being rinsed properly, fragrance, hard water, or a barrier that's had enough.
Oil, buildup, and the things worth stopping
How much oil your scalp makes is mostly hormonal and genetic and no shampoo is changing that. What you can change is what's sitting on top of it, and for a lot of people that's the real issue. Dry shampoo layered on dry shampoo across four or five days, silicones, styling product, conditioner going on too close to the root. It all accumulates on the skin and around the follicle openings, and hair starts to feel heavy and greasy far faster than it should.
The other things I tell people to avoid: washing less often in the hope of training your scalp, because your scalp cannot be trained and all that happens is the oil and dead skin sit there longer. Shampooing only the ends, when shampoo is for the scalp and the lengths get cleaned on the way down. Scratching with your nails. And rushing it, because most people are not washing their scalp for anything close to long enough to actually clean it. A full minute of fingertips on skin, and shampoo twice if there's a lot of product to get through.
Once a week I'd build in something more thorough than your usual wash. Not harsher, because a stripped scalp itches and flakes more rather than less, but a proper reset that lifts what regular shampoo leaves behind. That's where the Cascata Detox + Restore Scalp Shampoo sits nicely. It's formulated to deep cleanse the scalp and clear buildup, and it manages to do that without leaving the hair squeaky or stripped, which is the usual trade-off with a clarifying wash. When I talk about cleansers, I always say you don't want that squeaky clean feeling, and the same applies for the scalp here. Once a week as your reset, your normal shampoo the rest of the time.
When it's a GP conversation rather than a product one
Shedding is the thing that worries people more than anything else, so it's worth saying that you lose somewhere in the region of fifty to a hundred hairs a day and that is completely normal. Hair in the shower drain, on your pillow, in the brush, none of that is a problem on its own. Every follicle works on a cycle, growing for a few years, then having a short rest, then shedding that hair and starting again, and they're all doing it at different times so you don't notice. What illness or real stress or a big weight drop can do is push a load of follicles into that resting phase at the same time, and then a couple of months later they all let go together. That's why the timing catches people out. They feel fine by the time the hair starts coming out and can't connect the two.
Beyond that, if hair is coming out in patches, if there are areas where the scalp looks smooth and shiny and you can't make out the little follicle openings any more, if there's scaling and redness happening alongside hair loss, or if shedding starts suddenly and isn't settling after a few months, that's worth getting looked at rather than treated with a product. Low iron and thyroid problems are both common and both easy enough to check, and some types of hair loss have a narrower treatment window than people realise.
Otherwise, go and part your hair in a few places in good light and have an actual look at your scalp. Most people have never done it.
Dr Laura Lenihan
