Nonprescription omega-3 fish oil pills may cause an upset stomach, loose stools, nausea and a fishy taste in the mouth. They may also cause rashes, nosebleeds, heartburn and belching. Excessive doses may reduce the body's immune system's activity, leaving the body more vulnerable to infection, according to WebMD.Continue Reading
Freezing omega-3 fish oil supplements and taking them with meals can decrease the negative side effects. Those who have liver scarring from liver disease should avoid fish oil pills, as the pills may increase the risk of bleeding. People with an allergy to seafood may also want to avoid fish oil pills, as it is possible the pills may increase the risk of a reaction, explains WebMD.
People with bipolar disorder or depression should avoid omega-3 fish oil pills, as the pills may exacerbate these conditions. Because too many fish oil pills may make regulating blood sugar levels difficult, people with diabetes should not take them. People who take blood pressure-lowering medications should also avoid them, as they may drop blood pressure levels too low, notes WebMD.
People with heart conditions that require an implanted defibrillator should not take fish oil pills, as the pills may increase the chances of heartbeat irregularities. Those who suffer from familial adenomatous polyposis should also avoid fish oil pills, as the pills may increase the risk of cancer. In modest doses of 3 grams or less per day, fish oil is usually safe for most people, states WebMD.Learn more about Side Effects