Dr Kara Johns
Creator and Director of SBK
hello@sbk.store

An itchy scalp is one of those things we tend to brush off — pun intended. But if it’s persistent, it’s worth understanding why, because “itchy scalp or dry scalp” isn’t actually a medical diagnosis. They are symptoms. And symptoms are your skin’s way of telling you something specific is going on.

In clinic, I see a variety of causes of an itchy scalps, and the cause is never as simple as “needs more moisture.” Let’s go through the real, diagnosable conditions behind behind an itchy scalp — what they look like, and when it’s time to get it checked.

1. Seborrhoeic Dermatitis (and Dandruff)

The most common cause of an itchy, flaky scalp. It shows up as greasy, yellowish scale in oil-rich areas — scalp, hairline, eyebrows, sides of the nose. 'Dandruff' is actually the mildest form of this same condition — the uninflamed version, without the redness. 'Cradle cap' is the infant version 

What’s actually happening: the exact cause of seborrhoeic dermatitis is not fully understood, however, it seems to be from a combination of hormonal, nutritional, yeast and neurological factors. It is not about hygiene, and it comes and goes in flares, often worse with stress or in winter.

Managing it: encouraging skin turn over and regulating the microbiome (such as antifungal and anti-yeast shampoos that contain zinc pyrithione, ketoconazole, or selenium sulfide) are the mainstay of treatment, alongside keeping the scalp clean without over-stripping it.

2. Scalp Psoriasis

Distinguished by thick, well-defined, silvery-white plaques with redness underneath. Unlike seborrhoeic dermatitis, the scale is drier and more built-up, and it can extend past the hairline onto the forehead or behind the ears.

What’s actually happening: psoriasis is an immune-driven condition where skin cells are produced far faster than normal, so the stratum corneum — the outermost layer of dead skin cells — builds up faster than it can shed. That build-up is the plaque you can see and feel.

Managing it: because it’s a build-up problem, chemical exfoliants like salicylic acid are a key component of management — they help lift and soften the scale. This is usually paired with anti-inflammatory treatments prescribed by your doctor to address the immune drivers underneath.

3. Atopic Dermatitis (Eczema)

Yes — eczema can affect the scalp too, and I know this one personally. My skin flares with redness, dryness and intense itch, and fragrance is one of my biggest triggers.

What’s actually happening: atopic dermatitis comes from a genetically weakened skin barrier, which is more prone to react when it’s exposed to an irritant — fragrance being one of the most common. A compromised barrier lets moisture out and irritants in, which is what drives the itch-scratch cycle.

Managing it: the two priorities are avoiding your triggers and actively supporting the skin barrier — think calming, barrier-repairing ingredients like ceramides, niacinamide and panthenol, and steering clear of fragrance and harsh surfactants while it’s flaring.

4. Folliculitis

This is inflammation or infection around individual hair follicles, often showing up as small, tender, sometimes pus-filled bumps rather than diffuse flaking.

What’s actually happening: hair follicles become blocked or irritated — from built up skin, sweat, heat, tight hairstyles, friction, or product build-up — and this lets bacteria (commonly Staphylococcus) take hold and inflame the follicle.

Managing it: the fix is usually two-fold — treat the inflammation or infection (topical or oral antibacterial/antifungal treatment is sometimes needed), and remove the trigger, whether that’s easing up on tight styles, heavy occlusive products, or excess heat and sweat sitting on the scalp.

5. Tinea Capitis (Scalp Ringworm)

A fungal infection, more common in children, that can cause itchy, scaly patches — sometimes with patchy hair loss or broken hairs.

What’s actually happening: a dermatophyte fungus invades the hair shaft itself, not just the surface of the skin — which is why it behaves differently to the other conditions here.

Managing it: because the fungus sits inside the hair follicle, topical treatment alone can’t reach it — this one needs an oral antifungal, prescribed after a proper diagnosis. It’s also contagious, so combs, brushes, and pillowcases need attention too.

Caring for an Itchy Scalp

While you work out what’s driving it, some general principles help almost every scalp:

- Look for a scalp product that does three things at once — calms irritation, supports the skin barrier, and gently supports the natural turnover of the stratum corneum, rather than letting scale and build-up accumulate.  Salicylic acid is a key ingredient to look for. (Watch this space — this is exactly the gap we’ve been formulating for. More soon.)

- Avoid fragrance in hair and scalp products where you can — it’s a common irritant across several of these conditions

- Don’t over-wash or over-scrub — this can worsen barrier-dependent conditions like eczema and seborrhoeic dermatitis

- Be gentle with heat from styling tools, which can aggravate inflamed skin

- Resist the urge to self-diagnose long-term — what looks like “just dandruff” for months may be something else entirely

When to See a Doctor

Self management has its limits, and I always want you to know where they are. See a GP or dermatologist if:

- The itch or scale hasn’t improved after trying a few strategies yourself

- There’s pain, pus, spreading redness, or fever

- You notice hair loss or bald patches

- Symptoms recur again and again

These conditions can look similar on the surface but need different treatments — so a proper diagnosis matters more than guesswork.

A Personal Note

I’ve had atopic dermatitis for as long as I can remember. It’s part of why I formulate the way I do — fragrance is one of the most common triggers for flares, both in the research and in my own skin. When I started SBK, avoiding fragrance wasn’t a marketing decision. It was personal and evidence based.

I hear the same story constantly in clinic: patients who’ve tried product after product, assuming they just haven’t found “the right one” yet, when actually their skin has been reacting to the same or similar irritant across multiple brands the whole time.

Watch This Space

Scalp care has been on my mind for a while now — for all the reasons above. We will be releasing a scalp product soon, formulated with the same evidence-based, fragrance-free approach behind everything else we make. 

If your scalp has been bothering you, you’re not alone — and you don’t need to just live with it. Understanding what’s actually going on is the first step.

This blog will be updated soon!