Online shopping returns are a growing sustainability issue. Nudging consumers with message frames can promote sustainable behaviours and may help reduce product returns. In three studies, we investigate parcel-included message frames that highlight the negative consequences of returns for the environment, logistics workers, and consumers. An initial qualitative study shows that while consumers appreciate efforts to reduce returns, they may resist, indicating reactance. A subsequent experimental study demonstrates that the three message frames lead to a contrary outcome—increased return intentions. A third study reveals that message frames increase reactance, which mediates return intentions and decreases shop revisit intentions. The effect on reactance is moderated by gender, being stronger for women. These findings provide IS research with insights into when nudges cause unintended effects and suggest future research opportunities on product return behaviour.