Does tachyphylaxis occur in long‐term management of scalp seborrheic dermatitis with pyrithione zinc‐based treatments?

In a 2008 study, researchers found no evidence of tachyphylaxis, or decreased effectiveness, in the long-term use of pyrithione zinc (PTZ)-based shampoos for treating scalp seborrheic dermatitis. Despite 64% of surveyed dermatologists believing in the occurrence of tachyphylaxis with PTZ treatments, clinical studies involving 125 individuals over 24 weeks and 37 individuals over 48 weeks showed consistent benefits compared to placebo at all time points. Only about 2% of participants showed any potential for tachyphylaxis, leading to the conclusion that the perceived decrease in treatment effectiveness over time is more likely due to compliance issues rather than true tachyphylaxis.