BackgroundPatient health literacy (HL) affects health and wellbeing on both individual and population levels. The ability to receive, understand, manage and act upon health information can be positively influenced by nurses’ use of HL strategies. This study examined the relationship between nurses’ use of a HL checklist (intervention) and before and after patient HL scores, and the effects of frequency and types of strategies used in specialty consultations in Spain.MethodsThis quasi-experimental, non-randomized study used the HLS19-Q12 to calculate HL scores for 149 patients. Calculations were performed both before and after a nursing intervention that consisted of using a HL checklist. Paired samples t-test assessed the difference between patient HL scores pre- and post-nurse intervention. Frequency analysis and Pearson correlation where used to examine frequencies of nursing HL strategies used and associations with HL scores.ResultsThe mean difference between the HLS19-Q12 scores before and after intervention was − 9.94, with a standard deviation of 11.50. There was a statistically significant effect of the intervention on HL score (t = -10.00, p < 0.001). No participant had HL classified as ‘inadequate’ after the nursing intervention. Verbal teach back method was the most frequent strategy used by nurses, and the use of a computer image was the most frequent visual aid.ConclusionsThe use of a standardized HL intervention by nurses was shown to have a positive effect on patient general HL scores in specialty consultations in Spain. These results not only suggest that the use of a HL checklist can be an effective HL tool, but also reinforce the potential of nurses to make a positive impact on both individual and population health. Overall, these findings provide data that can be used by health systems, hospitals management, and nurse education programs to adopt strategies to improve patient HL and health outcomes, while potentially lowering costs and ineffective resource utilization related to inadequate HL.