Those strange orange patches may not actually be “stains” at all. On gray, blue, and other dark-colored towels, one of the most common causes is benzoyl peroxide, an ingredient found in many acne washes, creams, and spot treatments. Instead of depositing orange material onto the fabric, benzoyl peroxide can bleach or permanently alter the dye, leaving behind peach, orange, pink, or pale patches that won’t disappear in the washing machine. Official benzoyl peroxide product labels specifically warn that the ingredient can bleach dyed fabrics.

The transfer can happen surprisingly easily. Someone washes their face with an acne cleanser, dries off with the towel, or leaves a little medication on their hands or skin. Even a small amount can react with the towel’s dye. Because the discoloration may not become obvious immediately, people often assume something in the washing machine caused it.

If nobody in the household uses benzoyl peroxide, another possibility is iron or rust in the water, which can leave genuine orange-brown deposits on fabric. But those marks usually look more like staining, whereas the pale orange patches shown here look more consistent with lost or altered dye.

Unfortunately, once the towel’s color has been chemically bleached, normal washing usually can’t restore it. The best prevention is to check acne and skincare products for benzoyl peroxide, rinse thoroughly after using them, and keep separate white towels for face washing.

So if every dark towel eventually develops mysterious orange patches, check the bathroom products before blaming the detergent.

The culprit may be sitting right beside the sink.