Head & Shoulders

In 1949 a chemical engineer and bacteriologist was hired with an assignment that sounds like a joke and was not: rid the world of dandruff. It took him and his team roughly a decade, which is a fair measure of how hard the problem actually is.

The treatments available then were coal tar and egg oil, both effective enough and both unpleasant enough that compliance was the real obstacle. What John Parran Jr and his colleagues wanted was an active that worked without making hair smell like a road being resurfaced. They settled on pyrithione zinc, and the shampoo built around it launched on the first day of 1961.

The compound turned out to be doing something nobody fully understood at the time. Dandruff is not a dryness problem, which is why moisturising a flaking scalp tends to make it worse; it is an inflammatory response to Malassezia, a yeast that lives on almost everyone and feeds on scalp oil. Pyrithione zinc is an antifungal. The brand spent decades selling flake control while quietly operating one of the most widely used antifungal treatments in the world, and the range has since branched into selenium sulfide and piroctone olamine at various strengths.

The honest read is that the chemistry is sound and the marketing has grown baggier than the science. The medicated core works, and the evidence behind its actives is among the strongest in any consumer hair category. But the line now runs to dozens of variants where the cosmetic story of volume, colour safety, scent and hair type crowds the active into the small print, and a shampoo bought for its fragrance is a different purchase from a shampoo bought for its antifungal. The thing the packaging never says loudly enough is that contact time is most of the treatment. An antifungal rinsed away in fifteen seconds is barely a treatment; left on the scalp for a few minutes, two or three times a week, the plainest version of this does most of what the elaborate ones do.

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