EPO is generally safe and well-tolerated. The most common side effects include headache and gastrointestinal symptoms (e.g., heart burn, nausea, vomiting, diarrhea, abdominal pain, flatulence).[1][2] When used prior to childbirth, reported side effects include meconium-stained amniotic fluid, premature membrane rupture, and arrest of descent;[3] and in one case report, a woman using both EPO and raspberry leaf tea before labor gave birth to an infant with widespread bruising.[4]
EPO might increase the risk of bleeding, particularly if combined with other blood-thinning medications (e.g., warfarin).[5] Although evidence is limited, EPO may have an inhibitory effect on certain cytochrome P450 (CYP450) enzymes involved in drug metabolism, which could theoretically alter the efficacy or increase the risk of side effects with some medications; however, the clinical relevance of this is unclear.[6] In one case report, EPO administration seemed to increase blood levels of an anti-retroviral medication (lopinavir/ritonavir) used for managing HIV, and the proposed mechanism was CYP450 enzyme inhibition.[7]
Case reports have suggested that EPO may increase the risk of seizures.[8][9] In all cases, EPO was administered to people with schizophrenia along with phenothiazine drugs, which are known to increase the risk of seizures, and all of the individuals had a history of seizures or abnormal brain wave activity. However, the mechanism behind this is unclear, and animal research suggests that the primary fatty acids in EPO (linoleic acid and GLA) and their metabolites may instead be protective against seizures.[10][5]