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Glutamine 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

  • Very well tolerated — one of the safest amino acid supplements even at high doses
  • Rare GI symptoms (bloating, constipation) at very high single doses
  • Theoretical concern: high-dose glutamine in cancer patients (as a tumor fuel source) — consult oncologist

Drug & Supplement Interactions

  • Lactulose — glutamine may reduce the efficacy of lactulose for hepatic encephalopathy by providing additional nitrogen
  • Anti-seizure medications — glutamine can be converted to glutamate; theoretical interaction (clinically insignificant at normal doses)
  • Chemotherapy — consult oncologist; glutamine may protect against mucositis but theoretical concern about tumor fuel

Maximum Dose

Do not exceed: 30 g/day in divided doses; well tolerated even at high doses in clinical settings

Full Glutamine Guide

References

  1. RCTCastell LM, Poortmans JR, Newsholme EA (1996). Does glutamine have a role in reducing infections in athletes?. European Journal of Applied Physiology. DOI PubMed
  2. RCTCandow DG, Chilibeck PD, Burke DG, et al. (2001). Effect of glutamine supplementation combined with resistance training in young adults. European Journal of Applied Physiology. DOI PubMed
  3. Meta-analysisChen L, Wang D, Meng C, Sun H, et al. (2025). Glutamine prevents diarrhea in colorectal cancer patients undergoing chemotherapy or chemoradiotherapy: a meta-analysis.. BMC gastroenterology. DOI PubMed
  4. Meta-analysisAbbasi F, Haghighat Lari MM, Khosravi GR, Mansouri E, et al. (2024). A systematic review and meta-analysis of clinical trials on the effects of glutamine supplementation on gut permeability in adults.. Amino acids. DOI PubMed
  5. Meta-analysisTao W, Xu G, Zhou J, Luo Y, et al. (2024). Glutamine Supplementation on Burn Patients: A Systematic Review and Meta-analysis.. Journal of burn care & research : official publication of the American Burn Association. DOI PubMed
  6. Meta-analysisYue HY, Wang Y, Zeng J, Jiang H, et al. (2024). Enteral glutamine supplements for patients with severe burns: A systematic review and meta-analysis.. Chinese journal of traumatology = Zhonghua chuang shang za zhi. DOI PubMed
  7. Meta-analysisLiang B, Su J, Chen J, Shao H, et al. (2024). Glutamine enteral therapy for critically ill adult patients: An updated meta-analysis of randomized controlled trials and trial sequential analysis.. Clinical nutrition (Edinburgh, Scotland). DOI PubMed
Show 4 more references
  1. Meta-analysisChang HC, Huang WY, Chen PH, Huang TW, et al. (2024). Effectiveness of glutamine for the treatment of radiodermatitis in cancer patients: a meta-analysis of randomized controlled trials.. Supportive care in cancer : official journal of the Multinational Association of Supportive Care in Cancer. DOI PubMed
  2. ObservationalLi XK, Tu B, Zhang XA, Xu W, et al. (2023). Dysregulation of glutamine/glutamate metabolism in COVID-19 patients: A metabolism study in African population and mini meta-analysis.. Journal of medical virology. DOI PubMed
  3. Vidor MV, Panzenhagen AC, Martins AR, Cupertino RB, et al. (2022). Emerging findings of glutamate-glutamine imbalance in the medial prefrontal cortex in attention deficit/hyperactivity disorder: systematic review and meta-analysis of spectroscopy studies.. European archives of psychiatry and clinical neuroscience. DOI PubMed
  4. Meta-analysisArribas-López E, Zand N, Ojo O, Snowden MJ, et al. (2021). The Effect of Amino Acids on Wound Healing: A Systematic Review and Meta-Analysis on Arginine and Glutamine.. Nutrients. DOI PubMed