Do reminders to promote social distancing achieve the desired effects on behavior? Much of the existing literature analyses impacts on people's intentions to comply. We run a randomised controlled trial in Denmark to test different versions of a reminder to stay home at the beginning of the crisis. Using a two-stage design, we follow up with recipients and analyse their subsequent self-reported behaviour. We find that the reminder increases ex-ante intentions to comply when it emphasises the consequences of non-compliance for the subjects themselves and their families, while it has no effect when the emphasis is on other people or the country as a whole. We also find, however, that impacts on intentions do not translate into equivalent impacts on actions. Only people in poor health react to the reminder by staying home significantly more. Our results shed light on important gaps between people's intentions and their actions in responding to the recommendations of health authorities.