BACKGROUND: Social media is a common source of health-related information. However, more clarity regarding ACS symptom information posted on social media is needed. OBJECTIVES: The objective was to describe ACS symptom information on social media platforms, including Twitter (now named X), Instagram, and TikTok. METHODS: A cross-sectional, qualitative descriptive design was used. The three social media platforms were searched in 2022 for posts containing ACS symptom information. A random sample of posts meeting inclusion was drawn. Posts were analyzed using a qualitative coding process, and network analysis was used to triangulate data. RESULTS: Posts (N = 342) included in the final analysis were most often published by healthcare organizations (46.2 %), lay persons (20.8 %), or healthcare professionals (13.7 %). Five key themes were identified: 1) a focus on gendered symptom experiences, 2) diverse types of symptom messages (educational, emphasis on getting help, personal testimony, advertising, diagnostic help, research findings), 3) variety of specific symptoms mentioned, 4) different dimensions of symptoms included, and 5) varying levels of information quality and accuracy. Chest pain was the most common ACS symptom highlighted in posts, and symptom differences between men and women were often emphasized. CONCLUSIONS: Of particular concern was incorrect or misleading ACS symptom information on social media that could create misconceptions and contribute to delays in seeking care for ACS. The findings from this study provide more insight into the ACS symptom information shared on social media platforms and provide preliminary information that can influence practice and future research.