Are there any bad side effects from fish oil?

Regular fish oil intake exceeding 3 grams daily may suppress the ability of the immune system to fight infection and hamper blood clotting. Daily doses fewer than 3 grams have no serious side effects for most individuals, according to WebMD.

AIDS and HIV patients are at an increased risk of developing low immunity levels from fish oil, WebMD states. Individuals with liver disease occasionally develop internal bleeding, and diabetics may find blood sugar levels harder to control from excessive intake. Omega-3 fatty acid may also worsen symptoms in persons with bipolar disorder or depression; patients taking medications to lower their blood pressure may be at risk for too steep of a decline.