Dry scalp vs dandruff: they require different treatments
Dry scalp and dandruff look identical — both produce white flakes — but they have completely different causes and require different treatments. Dry scalp is simply lack of moisture and lipid production in the scalp. Flakes are small, white, and dry. Scalp feels tight, itchy, and uncomfortable. Caused by: cold weather, over-washing, harsh shampoos stripping the scalp's natural oils, or hard water deposits. Treatment: increase scalp oil production with occlusive oils (jojoba, argan), reduce shampoo frequency, and switch to a sulphate-free cleanser. Dandruff (Pityriasis capitis) is caused by an overgrowth of Malassezia globosa, a naturally occurring yeast on the scalp. Flakes are larger, oilier, and yellowish. Scalp may appear red or irritated. Requires antifungal treatment, not simply moisturisation. Treating dandruff as dry scalp with oils can worsen the condition — Malassezia feeds on fatty acids in oils.
The most effective antifungal ingredients for dandruff
For true dandruff and seborrheic dermatitis, antifungal active ingredients are the correct treatment. Evidence-ranked from strongest to gentlest: Ketoconazole 1–2%: the gold standard antifungal for seborrheic dermatitis. A 2005 systematic review found ketoconazole 2% shampoo significantly superior to placebo and comparable to ciclopirox. Available OTC at 1% concentration. Selenium sulphide 1%: disrupts the Malassezia cell membrane; effective for moderate dandruff. Zinc pyrithione 1–2%: the active in most standard anti-dandruff shampoos (Head & Shoulders). Sustained antifungal effect with regular use. Ciclopirox 1.5%: broad-spectrum antifungal, prescription strength in most markets. Coal tar 0.5–5%: reduces cell turnover and has antifungal properties; highly effective but leaves residue and odour. For mild dandruff, rotate between a zinc pyrithione shampoo (2–3x weekly) and a salicylic acid scalp treatment (weekly) to control flaking without drying the scalp.
Scalp build-up: causes and exfoliation methods
Scalp build-up is the accumulation of dead skin cells, sebum, product residue (from dry shampoos, styling products, and conditioners), and sometimes mineral deposits from hard water — all on the scalp surface. It is distinct from dandruff (though they can co-exist). Signs of build-up: scalp feels congested, hair feels flat and heavy at the roots, itching without obvious flaking, and hair products seem less effective. Treatment: scalp scrub once per week — a physical exfoliant (sugar or salt based) or chemical exfoliant (salicylic acid serum). Wet the scalp thoroughly first. Apply scrub to sections of the scalp and massage firmly with fingertips for 2–3 minutes. The goal is to physically lift and remove the accumulated debris from the scalp surface and follicle openings. Follow with a sulphate shampoo (the one occasion sulphate shampoos are appropriate) to fully rinse all loosened debris.
DHT and scalp health: the androgenic alopecia connection
Dihydrotestosterone (DHT) is produced when 5-alpha-reductase enzyme converts testosterone to DHT in the scalp. DHT binds to androgen receptors in hair follicles and causes follicle miniaturisation over time — the gradual shrinking of follicles that produces progressively finer, shorter hairs and eventually follicle dormancy. This is the primary mechanism of androgenic alopecia (pattern hair loss) in both men and women. DHT-blocking scalp serums target this process topically. Evidence-backed DHT blockers in scalp serums: saw palmetto extract (Serenoa repens) — a 2014 study found saw palmetto equivalent to finasteride for improving hair count in mild-to-moderate androgenic alopecia. Pumpkin seed oil — a 2014 trial in Evidence-Based Complementary and Alternative Medicine found 24 weeks of pumpkin seed oil significantly increased hair count versus placebo. Caffeine — stimulates follicle elongation and counteracts DHT-induced follicle shrinkage in in-vitro studies.
Building a complete scalp care routine
A complete scalp care routine addresses cleansing, exfoliation, and treatment. Weekly exfoliation: use a scalp scrub or 2% salicylic acid scalp treatment once per week before shampooing. Leave on for 5–10 minutes, then shampoo thoroughly. Washing frequency: wash oily scalps every 2–3 days; dry or low-porosity scalps 1–2 times per week. Over-washing strips the scalp's protective lipid film and triggers compensatory sebum overproduction. Daily treatment serum: apply a scalp serum containing rosemary oil, caffeine, or saw palmetto to the scalp after washing. Section the hair, apply directly to the scalp in rows, and massage for 3–5 minutes. Do not rinse. Leave overnight for maximum absorption. Scalp massage: 4 minutes of daily fingertip massage — even without any product — is independently associated with increased hair thickness (2016 ePlasty study).