Blood donation in Spain is an altruistic, voluntary and unpaid process. Despite its social and health significance, this process has suffered a standstill in recent years that has been aggravated by the coronavirus pandemic. To promote the generation of new donors, it is necessary to carry out campaigns aimed at younger age groups to improve the information they have and reduce their fears. This research analyses the effectiveness of different frames of a persuasive narrative to increase blood donation. These frames have been constructed from two variables: an emotional appeal (empathy awakened by a recipient protagonist versus the pride experienced by a donor protagonist) and the identification of the beneficiary of the donation (identifiable victim versus generic beneficiary). The manipulated narratives incorporate features of edutainment and are adapted to the tone and language of the target population, young people, in the format of a Twitter thread. To test the effectiveness of these narratives, an experimental study was conducted among 600 participants aged 18–30 years. The results show the effectiveness of the emotional appeal, specifically in the threads that are led by a recipient of the blood donation. This appeal induces greater identification among people who perceive themselves as a little or somewhat similar to the protagonist. This outcome in turn positively affects information recall, the intention to share the message and the attitude towards donation, and reduces the perceived risk. All in all, it increases the donation intention. The data confirm a moderated mediation model with identification as a mediator and similarity as a moderator. On the contrary, no statistically significant effects were found regarding the second manipulated variable. No evidence was found that the use of an identifiable beneficiary in the donation appeal obtained better results than the call to donate supported by generic data.