Is krill oil a safe and effective source of omega 3?

Krill oil is likely safe for adults when used for short amounts of time, up to three months, recommends WebMD. The side effects are similar to those of fish oil, such as bad breath, heartburn, upset stomach and loose stools.

People who are allergic to seafood might also be allergic to krill oil supplements, states WebMD. Krill oil can slow blood clotting and might increase the risk of bleeding during surgery, therefore it is recommended to discontinue using krill oil two weeks prior to having surgery. Krill oil is not recommended during pregnancy and breastfeeding because not enough is known about its affect.