Erythropoiesis-stimulating agents (ESA) are medications which stimulate the bone marrow to make red blood cells.

[1] They are used to treat anemia due to end stage kidney disease, chemotherapy, major surgery, or certain treatments in HIV/AIDS.

[4] Serious side effects may include heart attacks, stroke, increased cancer growth, or pure red cell aplasia.

[8] Medical speciality professional organizations do not recommend the use of ESAs in people with chronic kidney disease (CKD) who have hemoglobin levels greater than 10 g/dL and do not have anemia symptoms.

[10] The 2020 Cochrane Anaesthesia Review Group review of erythropoietin (EPO) plus iron versus control treatment including placebo or iron for preoperative anaemic adults undergoing non‐cardiac surgery[11] demonstrated that patients were much less likely to require red cell transfusion and in those transfused, the volumes were unchanged (mean difference -0.09, 95% CI -0.23 to 0.05).

Recombinant erythropoietin has a variety of glycosylation patterns giving rise to alpha, beta, delta, and omega forms: Darbepoetin alfa, which early literature during its development often termed as novel erythropoiesis-stimulating protein (NESP), is a form created by five substitutions (Asn-30, Thr-32, Val-87, Asn-88 and Thr-90) that create two new N-glycosylation sites.

[citation needed] Though EPO was believed to be widely used in the 1990s in certain sports, there was no way at the time to directly test for it, until in 2000, when a test developed by scientists at the French national antidoping laboratory (LNDD) and endorsed by the World Anti-Doping Agency (WADA) was introduced to detect pharmaceutical EPO by distinguishing it from the nearly identical natural hormone normally present in an athlete's urine.

[36] Dr. Michele Ferrari, a former student and protege of Conconi,[37] had a controversial interview mentioning the drug in 1994, just after his Gewiss–Ballan team had a remarkable performance in the La Flèche Wallonne race.

Ferrari told l'Equipe journalist Jean-Michel Rouet that EPO had no "fundamental" effect on performance and that if his riders used it, it would not "scandalize" himself.

[38][39] Ferrari was fired shortly after, but continued to work in the industry with top riders, allegedly including Lance Armstrong.

[37][40] That same year, Sandro Donati, working for the Italian National Olympic Committee, presented a report accusing Conconi of being linked to the use of EPO in the sport.

[36] In 1997, the Union Cycliste Internationale (UCI) instituted a new rule that riders testing above 50% haematocrit were not only immediately disqualified, but banned from racing for two weeks.

[46] In 2012, the USADA released a report on its investigation into massive doping by the US Postal Service cycling team under the leadership of Lance Armstrong.

The report contained affidavits from numerous riders on the team, including Frankie Andreu, Tyler Hamilton, George Hincapie, Floyd Landis, Levi Leipheimer, and others, outlining that they and Armstrong used a cocktail of performance-enhancing substances for the Tour de France, most notably EPO, during Armstrong's seven consecutive Tour wins.

Longstanding precedent in U.S. law holds that the statute of limitations does not apply in cases of fraudulent conduct by a defendant.

There were concerns that such production would also make Dynepo undetectable in the urine tests for EPO used, at that time, to detect doping by athletes.