Article content Once that diagnosis became clear, it is easy to point to a distinguishing symptom. For people with POTS, standing upright triggers a debilitating racing of the heart. Article content Recommended Videos We apologize, but this video has failed to load. Try refreshing your browser, or POTS: When standing up makes you sick Back to video We apologize, but this video has failed to load. In others, there may be abnormalities involving the immune system, blood volume, or the body’s response to infection.