Abstract Background The rapid spread of COVID-19 required swift action to provide people with rheumatic and musculoskeletal diseases (RMDs) with reliable information. People with limited health literacy constitute a vulnerable group that might have difficulty accessing, understanding and applying health information, particularly in times of crisis. Objectives This study explored (a) key aspects of crisis communication and (b) explicit consideration of people’s health literacy needs in communication to people with RMDs during the first wave of COVID-19 in the Netherlands. Methods We conducted a convergent, qualitatively driven mixed-methods study comprising seven qualitative interviews with professional representatives of organisations responsible for information provision to people with RMDs, and quantitative analysis of 15 patient information materials distributed by these organisations. The study was guided by principles of crisis communication and health literacy. We assessed understandability and actionability of information materials using the Dutch version of the Patient Education Materials Assessment Tool (PEMAT, resulting in a percentage of quality criteria met), and language difficulty level using an online application (assessing difficult words, jargon, passive, complex and long sentences, long paragraphs, and difficulty levels according to the Common European Framework of Reference for Languages (CEFR, from A1 (basic) to C2 (proficient))). Results Respondents reported lack of preparedness, challenges related to scientific uncertainty and reaching the target group, difficulty simplifying information, and uncertainty regarding adequacy of the communication approach. Patient information materials (written and video) showed variation in actionability (range 60–100%) and understandability (range 58–100%), and 69% of written materials were too difficult, mostly due to the use of long sentences and difficult words. The quantitative findings were in coherence with the limitations in communication reported by ...