Fish oil is likely safe for most people in doses of 3 grams or less daily. Taking more than 3 grams daily might increase the chance of bleeding. Fish oil side effects include heartburn, loose stools, and nosebleeds. Taking fish oil supplements with meals or freezing them can reduce these issues.
It is also important to note that contrary to popular beliefs that taking fish oil directly from fish is the best, consuming high amounts of fish oil from DIETARY sources is possibly unsafe. Some fish are contaminated with mercury and other chemicals. Fish oil supplements typically do not contain these chemicals.