"Shark bites vary in intensity and severity, but the main issue that all of them share is the need to stop the bleeding," Perry told Fox News Digital. Because shark teeth can easily tear through major arteries, veins and tendons, uncontrolled blood loss is the biggest immediate threat. Panic increases heart rate and blood pressure, which accelerates blood loss, the doctor noted. A sudden drop in blood pressure and the body's stress response may trigger fainting. 5: Prepare for secondary risksWhile controlling blood loss is crucial in the first five minutes, long-term recovery involves fighting off severe marine bacteria.