Dandruff and seborrhoeic dermatitis

What it is

Seborrhoeic dermatitis is a common inflammatory condition linked to a normal skin yeast (Malassezia). It causes flaking (dandruff), itch and greasy scale on the scalp, eyebrows, sides of the nose, beard and behind the ears.

How it works

Dandruff and seborrhoeic dermatitis are linked to Malassezia yeast, which lives on oily skin. In some people the yeast breaks down scalp oil into irritating substances, speeding skin turnover and causing flakes, itch and redness.

Why it matters on darker skin

On darker skin it may appear as lighter or darker patches with fine scale, and in tightly curled hair it is common because of less frequent washing and heavy oils that feed the yeast.

Causes and triggers

Infrequent washing, oily scalp, stress, cold dry weather, heavy oils or greases applied to the scalp, and some conditions affecting immunity.

What helps — and why it works

Medicated shampoos containing ketoconazole, selenium sulfide, zinc pyrithione or coal tar work well. For textured hair, apply to the scalp, leave for 5 minutes, rinse, then condition the lengths; using it once a week can be enough. A doctor may suggest a short course of an anti-inflammatory lotion for flares. Medicated shampoo 2–3 times a week: ketoconazole, zinc pyrithione or selenium sulfide reduce yeast. Expected timeline: 1–4 weeks. Leave on the scalp 3–5 minutes: gives the active time to work. Condition lengths afterwards: medicated shampoos can dry textured hair.

What to avoid and why

Avoid heavy oils and greases on the scalp, which can worsen flaking, and picking at scale.

Common mistakes

• Adding more oil or grease to 'moisturise' flakes — this can feed the yeast.
• Washing too rarely.
• Scratching with combs.

Handling textured hair gently

Coily and curly hair is naturally the most fragile hair type because each bend in the strand is a weak point and natural oils travel down it slowly. That makes handling — how often and how firmly hair is combed, styled and pulled — as important as which products you buy. Detangle only when hair is wet and coated in conditioner, working in sections from the ends towards the roots with fingers or a wide-tooth comb. Keep heat to the lowest effective setting and always use a heat protectant. Sleep on satin or silk, or wear a satin bonnet, to reduce friction. Between wash days, a water-based leave-in followed by a light oil or cream helps hold moisture. Give the scalp attention too: it is skin, and needs regular cleansing, especially under wigs, weaves and braids, to prevent build-up, itch and infection. Any style that hurts, causes bumps or leaves the scalp tender is too tight and should be loosened. Hair grows about one centimetre a month, so changes in care take two to three months to show in length and thickness.

Scalp health and product choice

Choose a shampoo that suits the scalp and a conditioner that suits the lengths: the scalp may need cleansing or a medicated shampoo while the ends need moisture. Fragrance, essential oils and heavy waxes can irritate a sensitive scalp or cause build-up, and heavy oils on the scalp may worsen dandruff. Look for a clear ingredient list and a NAFDAC number, and patch-test new dyes and relaxers 48 hours before every use. Products that promise dramatic growth are usually untested; the treatments with the best evidence for pattern hair loss are medicines such as minoxidil, which should be started only after speaking to a pharmacist or doctor. Signs that you need medical advice rather than a new product include patches of hair loss, scarring or shiny skin, pain, pus, or shedding that continues for more than six months.

Questions to ask your doctor or pharmacist

Useful questions include: What do you think is causing this? Is it likely to come back, and how can I prevent it? Which products should I stop? How long before I should expect improvement, and when should I come back if it isn't better? Are there side effects to watch for? Is this treatment safe if I am pregnant, breastfeeding or for my child? Writing your questions down, bringing your products (or photos of their labels) and taking dated photos of the problem make an appointment much more useful.