Our skin is designed to shed old skin cells and grow new ones. Dandruff, however, is a kink in this assembly-line process, causing old skin cells on the scalp to build up and clump into the unsightly flakes that land on your favourite black shirt. About half of the adult population will suffer from a flaky scalp at some point.
Factors that may contribute to dandruff include seborrheic dermatitis, dry skin and certain skin conditions. Seborrheic dermatitis is a skin condition marked by large yellow scales, redness and inflammation of the scalp, or of other areas of the skin. While you might associate dandruff with a dry, flaking scalp, “it is actually caused by excess oiliness,” explains dermatologist Dr Charlene Linzon.
The culprit here is a common group of yeasts called Malassezia that grow on everyone, and it feeds on oil from the scalp, Linzon says.
What tips the scale in dandruff’s favour depends on the individual: how much oil your scalp produces, and how vigorously the yeast grows. “The yeast breaks down scalp oil, leaving behind a by-product [unsaturated fatty acid] that causes the flaking associated with dandruff, and the irritation, inflammation and scaling that define seborrheic dermatitis,” says Linzon.
Dandruff is also more likely to develop at certain stages of life, such as in infancy (called cradle cap), and around puberty, when oil (sebum) secretion increases, providing more food for yeast. Stress also increases oil production.
Thankfully, you can usually get this problem under control with over-the-counter (OTC) products. Start by shampooing your scalp frequently with a medicated shampoo to reduce oiliness. Here are your choices:
The active ingredients in these are zinc pyrithione, selenium sulphide and ketoconazole. They slow down the growth of the yeast that causes the flaking and scaling.
- Coal tar
The active ingredient in this product slows skin cell turnover, and also works as an anti-inflammatory, says Linzon.
- Salicylic acid
These shampoos boast a keratolytic agent, which helps to loosen and dislodge scales, explains Linzon.
How you use dandruff products can affect how well they fight flakes. Dr Charlene Linzon offers these tips:
- Switch products regularly, alternating between two or three kinds. For example, you could use, say, Nizoral one day and Head & Shoulders the next; or alternate every second or third time you shampoo.
- Leave shampoo on long enough to do its job – five to ten minutes, or, for a more intensive treatment, 20 to 30 minutes (once every couple of weeks).
- Use more frequently. Labels usually suggest using a shampoo twice weekly, but daily use is helpful for some. (Just watch for hair breakage and dryness – signs that you’re overdoing it.)
- Consult a GP or dermatologist if you have no relief after a month.