Introduction:
Medication adherence is influenced by both psychological and medical factors, including risk communication and numeracy skills. The way side-effect information is presented – whether in a positive or negative frame, and whether numerical data is conveyed in frequencies or percentages – can impact adherence. These effects may be more pronounced for individuals with lower numeracy.

Aim:
This study examines how framing and number formats affect risk perception, moderated by numeracy skills, while exploring emotional responses to medication side effects and intentions to use the medication.

Material and methods:
Participants (N = 332) were asked to read a medication description with varying side-effect information based on experimental conditions. They were randomly assigned to a 3 (frame: positive, negative, combined) × 2 (numerical format: percentages, frequencies) between-subjects design. The study assessed risk perception, medication intention, and emotional responses while considering participants’ numeracy levels. Materials and data are available at: https://osf.io/83ura.

Results and discussion:
Framing and numerical format significantly influenced risk perception and medication intention. Negative framing and frequency-based formats resulted in higher risk perception and lower medication intention. Moreover, numeracy interacted with the numerical format: individuals with lower numeracy showed higher medication intention in the percentage format and reported more negative emotions in the frequency format.

Conclusions:
The way information is framed and presented numerically plays a significant role in shaping risk perception and medication intention. Negative framing and frequency formats tend to increase perceived risk and decrease medication intention. Tailoring communication based on numeracy levels could improve medication adherence.