Taking omega-3 supplements in the forms of krill and fish oil does not appear to carry any significant side effects.
Minor side effects may include: bad breath, diarrhea, headache, heartburn, unpleasant-smelling sweat and upset stomach
However, omega-3 supplements, such as krill oil and fish oil, may have the potential to interact negatively with blood-thinning medications. If you have any pre-existing conditions, do always consult a doctor.