Background: Hypothyroidism is a common disease in elderly people. Although hypothyroidism can theoretically have clinical implications related to nearly all major organs, it is often excluded from diagnostic algorithms for elderly patients with multi-system disease because its symptoms are non-specific. Case summary: A 61-year-old woman presented with dizziness, fatigue, facial swelling, dry cracked skin, and myalgia. She had a 2-year history of impairment of multiple organs and multiple adverse drug events. Blood tests showed abnormal liver and kidney function, an elevated creatine kinase concentration, and hyperlipidaemia. During the last 2 years, she had experienced multiple severe adverse drug events, including eosinophilia and systemic symptoms caused by carbamazepine, acute kidney impairment related to ceftriaxone and cefdinir, exfoliative dermatitis caused by ceftazidime, and intolerance to statins. After visiting several large hospitals, she was finally diagnosed in our clinic with hypothyroidism. At the time of diagnosis, she was extremely ill and unable to walk independently. After taking levothyroxine, all of her symptoms and signs completely resolved. Conclusion: Hypothyroidism might be overlooked in elderly patients, especially those with complex and severe clinical conditions. Keywords: Aged; adverse drug events; multiple organ dysfunction; hypothyroidism.