Piroctone Olamine: Less Shedding, Thicker Strands

Piroctone olamine has evidence for reducing shedding and modestly improving hair retention. Two human studies show what that can mean in practice—and why fewer shed hairs, thicker strands and higher hair density need to be considered separately.

Six months of dandruff-shampoo use

A 2002 study enrolled 150 men with dandruff and shedding associated with androgenetic alopecia. Participants used shampoos containing 1% ketoconazole, piroctone olamine or zinc pyrithione two or three times a week for six months.

All three shampoos improved itching and dandruff, but hair density remained unchanged. Piroctone had the largest increase in strand diameter; ketoconazole had the largest reduction in shedding. There was no inactive-shampoo group.

Those are useful improvements for people dealing with shedding and dandruff. They do not establish piroctone as a stronger treatment for hormonal hair loss, and reduced sebum is not proof of an anti-androgenic action.

A modest hair-retention benefit against placebo

A 2021 study tested women with self-perceived thinning and generally symptom-free scalps. The shampoo comparison randomized 146 women, of whom 144 completed eight weeks. A 0.8% piroctone-olamine shampoo produced a 2.8-hair-per-square-centimeter advantage over placebo. A separate test of a daily leave-on preparation found a 3.2-hair-per-square-centimeter advantage over the placebo-treated side of the scalp.

The shampoo also improved measures of scalp condition. These modest gains support hair retention as a useful role for piroctone. The study was funded by Procter & Gamble and did not compare piroctone with ketoconazole or establish reversal of pattern baldness.

For the wider comparison, see what human shampoo studies found about shedding, thickness and hair counts.