Background <p>Hypertension is a prevalent chronic condition globally and in Taiwan, requiring long-term treatment and ongoing health management. Despite this, online and social media platforms have increasingly become channels for illegal advertisements of products claiming to lower blood pressure or improve cardiovascular health, which may be associated with patients’ health expectations and decision-making.</p> Objective <p>This study aimed to examine the content of illegal advertisements for drugs and health supplements targeting individuals with hypertension in Taiwan and to identify their persuasive strategies and potential associated risks.</p> Methods <p>Between September and November 2024, a total of 19 eligible illegal advertisements were collected through targeted online searches of Taiwan-based websites. The Public Disclosure Section for Misleading Advertisements provided by the national regulatory authority was used as a reference for identifying potential violation patterns. A qualitative content analysis was conducted, and advertisements were coded using predefined operational definitions.</p> Results <p>Three primary persuasive themes emerged from the analysis: authority-based appeals, efficacy-focused claims, and emotional strategies. Each theme comprised two categories: professional endorsement and certification (authority-based), promises of quick results and misleading claims of full recovery (efficacy-focused), and patient testimonials and celebrity endorsements (emotional). Advertisements employed multiple strategies simultaneously. Professional endorsement and certification were the most frequently observed authority-based cues within the collected advertisement corpus. Claims of quick results and full recovery may contribute to unrealistic expectations regarding disease treatment among patients and could obscure potential health risks. Patient testimonials and celebrity endorsements could appear to influence consumer behavior through emotional appeals. Overall, advertisements lacked transparent risk disclosures and credible scientific evidence.</p> Conclusions <p>This study identifies the strategic use of authority, efficacy, and emotional appeals in illegal online advertisements for hypertension-related products, may be relevant to consumer protection considerations. Regulatory authorities should strengthen real-time monitoring and enforce transparent information disclosure to protect vulnerable populations.</p>