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Krill Oil Side Effects & Safety

Evidence:Moderate
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This content is for informational purposes only and does not constitute medical advice. Statements about dietary supplements have not been evaluated by the FDA and are not intended to diagnose, treat, cure, or prevent any disease. Individual results may vary — consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • Mild GI discomfort (nausea, diarrhea, bloating) — less common than with fish oil due to phospholipid form
  • Fishy aftertaste — significantly less than fish oil due to natural astaxanthin antioxidant protection
  • Potential for increased bleeding time at high doses — clinically insignificant at standard doses
  • Loose stools — uncommon, typically resolves with dose adjustment or taking with food
  • Allergic reactions in individuals with shellfish/crustacean allergy — krill are crustaceans

Drug & Supplement Interactions

  • Anticoagulants and antiplatelets (warfarin, heparin, aspirin, clopidogrel) — omega-3s have additive antiplatelet effects; may increase bleeding risk
  • Antihypertensive medications — krill oil may modestly lower blood pressure; monitor for additive hypotension
  • Orlistat (weight loss medication) — may reduce absorption of fat-soluble nutrients including krill oil omega-3s; separate doses by 2+ hours
  • Other omega-3 supplements — additive effects; total EPA+DHA intake should be considered

Maximum Dose

Do not exceed: 4g/day (higher doses studied safely but offer diminishing returns; doses above 3g rarely needed)

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References

  1. RCTUlven SM, Kirkhus B, Lamglait A, Basu S, Elind E, Haider T, Berge K, Vik H, Pedersen JI (2011). Metabolic effects of krill oil are essentially similar to those of fish oil but at lower dose of EPA and DHA, in healthy volunteers. Lipids. DOI PubMed
  2. RCTBunea R, El Farrah K, Deutsch L (2004). Evaluation of the effects of Neptune Krill Oil on the clinical course of hyperlipidemia. Alternative Medicine Review. PubMed
  3. Sampalis F, Bunea R, Pelland MF, Kowalski O, Duguet N, Dupuis S (2003). Evaluation of the effects of Neptune Krill Oil on the management of premenstrual syndrome and dysmenorrhea. Alternative Therapies in Health and Medicine. PubMed
  4. Deutsch L (2007). Evaluation of the effect of Neptune Krill Oil on chronic inflammation and arthritic symptoms. Journal of the American College of Nutrition. DOI PubMed
  5. Ramprasath VR, Eyal I, Zchut S, Jones PJ (2013). Enhanced increase of omega-3 index in healthy individuals with response to 4-week n-3 fatty acid supplementation from krill oil versus fish oil. Lipids in Health and Disease. DOI PubMed
  6. Cicero AFG, Rosticci M, Morbini M, Cagnati M, Grandi E, Parini A, Borghi C (2016). Lipid-lowering and anti-inflammatory effects of omega 3 ethyl esters and krill oil: a randomized, cross-over, clinical trial. Archives of Medical Science. DOI PubMed
  7. Konagai C, Yanagimoto K, Hayamizu K, Han L, Tsuji T, Koga Y (2013). Effects of krill oil containing n-3 polyunsaturated fatty acids in phospholipid form on human brain function: a randomized controlled trial in healthy elderly volunteers. Clinical Interventions in Aging. DOI PubMed
Show 5 more references
  1. Meta-analysisMeng J, Wang X, Li Y, Xiang Y, et al. (2025). Krill oil for knee osteoarthritis: A meta-analysis of randomized controlled trials.. Medicine. DOI PubMed
  2. Pimentel T, Queiroz I, Florêncio de Mesquita C, Gallo Ruelas M, et al. (2024). Krill oil supplementation for knee pain: a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials.. Inflammopharmacology. DOI PubMed
  3. Meta-analysisHuang H, Liao D, He B, Zhou G, et al. (2023). Clinical effectiveness of krill oil supplementation on cardiovascular health in humans: An updated systematic review and meta-analysis of randomized controlled trials.. Diabetes & metabolic syndrome. DOI PubMed
  4. Kim MG, Yang I, Lee HS, Lee JY, et al. (2020). Lipid-modifying effects of krill oil vs fish oil: a network meta-analysis.. Nutrition reviews. DOI PubMed
  5. Meta-analysisUrsoniu S, Sahebkar A, Serban MC, Antal D, et al. (2017). Lipid-modifying effects of krill oil in humans: systematic review and meta-analysis of randomized controlled trials.. Nutrition reviews. DOI PubMed