Special caution should be taken with people who have fish and shellfish allergies. In addition, as with other omega-3 fatty acids, taking ethyl eicosapentaenoic acid (E-EPA) puts people who are on anticoagulants at risk for prolonged bleeding time.
The most commonly reported side effect in clinical trials has been joint pain; some people also reported pain in their mouth or throat. E-EPA has not been tested in pregnant women; it is excreted in breast milk and the effects on infants are not known.