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SupplementScience

Cod Liver Oil Side Effects & Safety

Reviewed by·PharmD, BCPS

This content is for informational purposes only and does not constitute medical advice. Consult your healthcare provider before starting any supplement. Full disclaimer

Safety Profile

Overall safety rating: Generally Safe

Potential Side Effects

  • Fishy aftertaste and burping — the most common complaint; reduced by enteric-coated capsules, taking with meals, or refrigerating liquid oil
  • GI discomfort — nausea, loose stools, or heartburn at higher doses
  • Vitamin A toxicity risk — unlike regular fish oil, cod liver oil contains preformed vitamin A (retinol); chronic intake above 10,000 IU/day can cause liver damage, headache, and bone thinning
  • Mild anticoagulant effect — omega-3s inhibit platelet aggregation; may increase bruising at high doses
  • Fishy body odor at higher doses reported by some users

Drug & Supplement Interactions

  • Anticoagulants (warfarin, heparin, aspirin) — omega-3s inhibit platelet aggregation; additive bleeding risk
  • Retinoid medications (isotretinoin, acitretin) — additive vitamin A toxicity; concurrent use may cause hypervitaminosis A
  • Vitamin D supplements — cod liver oil already provides vitamin D; combined intake may exceed safe upper limits
  • Antihypertensives — omega-3s may modestly lower blood pressure; additive hypotensive effect possible
  • Orlistat — fat-blocking drugs reduce absorption of fat-soluble vitamins A and D from cod liver oil

Maximum Dose

Do not exceed: 2 teaspoons (10ml) daily — higher doses risk vitamin A toxicity (hypervitaminosis A); if more omega-3s are needed, supplement with regular fish oil

Full Cod Liver Oil Guide

References

  1. Manson JE, Cook NR, Lee IM, Christen W, Bassuk SS, Mora S, Gibson H, Gordon D, Copeland T, D'Agostino D, Friedenberg G, Ridge C, Bubes V, Giovannucci EL, Willett WC, Buring JE (2019). Vitamin D supplements and prevention of cancer and cardiovascular disease. New England Journal of Medicine. DOI PubMed
  2. Aung T, Halsey J, Kromhout D, Gerstein HC, Marchioli R, Tavazzi L, Geleijnse JM, Rauch B, Ness A, Galan P, Chew EY, Bosch J, Collins R, Lewington S, Armitage J, Clarke R (2018). Associations of omega-3 fatty acid supplement use with cardiovascular disease risks: meta-analysis of 10 trials involving 77917 individuals. JAMA Cardiology. DOI PubMed
  3. Martineau AR, Jolliffe DA, Hooper RL, Greenberg L, Aloia JF, Bergman P, Dubnov-Raz G, Esposito S, Ganmaa D, Ginde AA, Goodall EC, Grant CC, Griffiths CJ, Janssens W, Laaksi I, Manaseki-Holland S, Mauger D, Murdoch DR, Neale R, Rees JR, Simpson S, Stelmach I, Kumar GT, Urashima M, Camargo CA (2017). Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data. BMJ. DOI PubMed
  4. Goldberg RJ, Katz J (2007). A meta-analysis of the analgesic effects of omega-3 polyunsaturated fatty acid supplementation for inflammatory joint pain. Pain. DOI PubMed
  5. Rajakumar K (2003). Vitamin D, cod-liver oil, sunlight, and rickets: a historical perspective. Pediatrics. DOI PubMed
  6. Gruenwald J, Graubaum HJ, Harde A (2002). Effect of cod liver oil on symptoms of rheumatoid arthritis. Advances in Therapy. DOI PubMed