What’s the difference between 1% ketoconazole shampoo and 2% ketoconazole shampoo?

The percentage refers to the concentration of ketoconazole—the antifungal medication that reduces dandruff and itching—in the shampoo. The 1% solution is usually available over the counter, while the stronger 2% version requires a prescription. For more severe itching and flakiness, 2% ketoconazole shampoo is often the better choice.