It’s a popular misconception that dandruff treatments can become ineffective with long-term use. In fact, Procter & Gamble found that two-thirds of surveyed dermatologists were under the impression that the body or the dandruff-causing fungus can essentially form a tolerance to one of the most common anti-dandruff active ingredients, pyrithione zinc. However, a recent study shows continued and consistent efficacy.
Examining 248 subjects’ scalps after 22 weeks of regular dandruff-shampoo use, researchers found that pyrithione zinc treatment remained effective across the board. In a separate study following 89 participants who used dandruff shampoo for 48 weeks, only 2% saw a decrease in potency.
P&G believes human error may have led to the widely-believed myth of declining efficiency, noting that even the shortest break from sustained treatment can make it seem like a product isn’t working as well as it used to.
