Recent evidence conducted by the Imperial College London and Queen Mary's School of Medicine and Dentistry suggests why Vioxx may increase risks of heart attacks and strokes. Vioxx also suppresses prostacyclin, a blood vessel protector that prevents blood clots, consequently increasing risk of a heart attack. Tim Warner, one of the professors who made the discovery said that "it is essential that we have a true understanding of their sites of action so that we can produce new, safe, and effective drugs for years to come."

Study may reveal cause of Vioxx side effects