The Argentinian open water swimmer Martín Carrizo didn’t participate to Olympic Games in Rio 2016 due to failing a drugs test. He got disqualified because he took a banned substance called EPO. The drug test was taken during the preparatory competition in Brazil.
We should know that substances like EPO are used in some clinics as a treatment for anaemia and toumors, so its have health benefits. The opposite happens if sportspeople take this king of drug to improve their performance. They will have long-term health problems as headache, drop the hair, increase the blood pressure, thrombosis, heart attack...