Pale orange, yellow, or pink patches on dark towels are typically caused by benzoyl peroxide, an acne treatment that acts as a stealth bleach.
By permanently oxidizing the fabric, it strips away the original dye rather than leaving a removable stain.
Unlike rust or bathroom bacteria marks, benzoyl peroxide damage cannot be restored by detergents, stain removers, or hot water.
Preventing ruined towels requires switching to white linens or rinsing thoroughly, though damaged towels can still be repurposed as cleaning rags.