The effects of minoxidil, 1% pyrithione zinc and a combination of both on hair density: a randomized controlled trial

Summary Background Recent studies of antidandruff shampoos or tonics containing antifungal or antibacterial agents produced effects suggestive of a potential hair growth benefit. Objectives The purpose of this 6‐month, 200‐patient, randomized, investigator‐blinded, parallel‐group clinical study was to assess the hair growth benefits of a 1% pyrithione zinc shampoo. The efficacy of a 1% pyrithione zinc shampoo (used daily), was compared with that of a 5% minoxidil topical solution (applied twice daily), a placebo shampoo and a combination of the 1% pyrithione zinc shampoo and the 5% minoxidil topical solution. Methods Two hundred healthy men between the ages of 18 and 49 years (inclusive) exhibiting Hamilton–Norwood type III vertex or type IV baldness were enrolled. Total hair counts, the primary efficacy measure, were obtained using fibre‐optic microscopy and a computer‐assisted, manual hair count method. Secondary measures of efficacy included assessments of hair diameter, as well as patient and investigator global assessments of improvement in hair growth. These were based on photographs of the scalp using both midline and vertex views. Results Hair count results showed a significant (P