Heatwaves are becoming more frequent in Germany due to climate change and regularly result in an increased number of deaths. Vulnerable groups during heatwaves include the elderly, children, outdoor workers, pregnant women, and people with chronic illnesses. Conditions that are particularly susceptible to heat include cardiovascular diseases, diabetes mellitus, chronic pulmonary and renal diseases, as well as mental illnesses. Medications can increase vulnerability to heat through increased adverse effects, including antihypertensives, anticholinergics, insulins, and transdermal opioids.