The Education
Fragrance-free covers the scent. It doesn't tell you the rest of the label.
The most common belief among people who already use a fragrance-free detergent is this: "All laundry detergent is basically the same." The ingredient comparison above shows why that belief doesn't hold when you look at the labels.
Here's what happens during a normal wash cycle. Your detergent mixes with water, lifts soil and odor from your fabrics, and then the rinse cycle is supposed to carry everything out. For fragrance, that process works. Fragrance molecules are water-soluble enough that most of them rinse away. That's why switching to a fragrance-free formula reduced your skin reactions, or your child's redness, by a meaningful amount.
But fragrance is not the only chemistry that can survive the rinse. 1,4-dioxane is one worth knowing about. It can form as a trace byproduct when liquid laundry detergents are manufactured, and the EPA's Integrated Risk Information System lists it as a likely human carcinogen. Reducing fragrance does not affect this. Because it forms during manufacturing rather than being added as an ingredient, it never appears on a label. The most reliable source on this one is the brand itself, through a published ingredient FAQ or a direct answer about how the formula is made.
The American Cleaning Institute has published surfactant residue studies showing measurable detergent residue on washed fabrics after the rinse cycle. The residue is not a failure of your washing machine. It's a predictable outcome of how conventional liquid detergent chemistry works. The carrier molecules that suspend the active surfactants in water do not all rinse out. Your clothes emerge from the dryer feeling clean. The fiber surface is a different story.
Switching from a scented formula to a fragrance-free one was a meaningful step. Understanding what's still in the formula is the next one.
Same wash. Different residue.