Can L‑glutamine worsen elevated liver transaminases (transaminitis)?

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Last updated: April 14, 2026 • View editorial policy

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L-Glutamine and Transaminitis Risk

L-glutamine can potentially worsen or cause transaminitis, though this appears to be a rare adverse effect based on available evidence. The FDA-approved labeling for L-glutamine does not list elevated liver transaminases as a recognized adverse reaction, but case reports document hepatotoxicity with glutamine supplementation 1, 2.

Evidence from FDA Drug Labeling

The FDA-approved prescribing information for L-glutamine (indicated for sickle cell disease) does not include transaminitis or hepatotoxicity among its adverse reactions 1. In clinical trials involving 187 patients receiving L-glutamine for up to one year, the most common adverse reactions were:

  • Constipation (21%)
  • Nausea (19%)
  • Headache (18%)
  • Abdominal pain (17%)

No elevation in liver transaminases was reported in these controlled trials 1.

Case Report Evidence of Hepatotoxicity

Despite the absence of liver toxicity signals in FDA trials, a 2020 case report documented the first case of glutamine-induced hepatotoxicity 2. A 35-year-old female athlete developed:

  • Severe abdominal pain
  • Scleral icterus
  • Impaired liver function tests

After three weeks of glutamine powder supplementation, she recovered within two weeks of discontinuation 2. This suggests that while rare, glutamine-associated hepatotoxicity is possible and reversible upon cessation.

Mechanistic Considerations

High Plasma Glutamine and Liver Dysfunction

Patients with acute liver failure often exhibit very high plasma glutamine concentrations 3. This creates a U-shaped relationship between glutamine levels and outcomes—both very low and very high levels associate with poor prognosis 3. The liver normally removes ammonia produced from glutamine metabolism; when liver function is impaired, glutamine accumulation may worsen hepatic dysfunction 3.

Chronic High-Dose Supplementation Concerns

A 2013 review highlighted potential side effects of chronic high-dose glutamine supplementation (~40 g/day), including 4:

  • Impaired ammonia detoxification
  • Enhanced glutamate and ammonia production
  • Alterations in amino acid metabolism

These metabolic perturbations could theoretically stress hepatic function, particularly in individuals with pre-existing liver compromise.

Clinical Guidance from ESPEN Guidelines

When NOT to Use Glutamine

The 2019 ESPEN ICU guideline explicitly states: "In ICU patients except burn and trauma patients, additional enteral glutamine should not be administered" (Grade B recommendation) 3. This reflects concerns about potential harm in certain populations, particularly those with liver dysfunction.

Contraindication Context

The ESPEN liver disease guideline (2020) does not specifically address glutamine supplementation in patients with elevated transaminases 5. However, it emphasizes monitoring liver biochemistry when introducing any intervention that could affect hepatic function.

Clinical Recommendations

If a patient develops transaminitis while taking L-glutamine:

  1. Discontinue glutamine supplementation immediately and monitor liver enzymes closely
  2. Exclude other causes of transaminitis (viral hepatitis, medications, alcohol, ischemia)
  3. Expect improvement within 2 weeks if glutamine is the culprit, based on the documented case 2
  4. Avoid rechallenge if hepatotoxicity is suspected

For patients with pre-existing liver disease or elevated transaminases:

  • Exercise caution with glutamine supplementation given the association between high plasma glutamine and liver failure 3
  • Consider baseline and periodic monitoring of liver enzymes if glutamine is deemed necessary
  • Use the lowest effective dose

Important Caveats

  • The hepatotoxicity risk appears very rare based on clinical trial data showing no signal in 187 patients 1
  • Most evidence for harm comes from a single case report 2 and theoretical concerns about ammonia metabolism 4
  • The FDA-approved formulation for sickle cell disease has not demonstrated liver toxicity in controlled settings
  • Patients with underlying liver disease may be at higher risk due to impaired glutamine metabolism 3

The balance of evidence suggests glutamine is generally safe for liver function in most patients, but rare idiosyncratic hepatotoxicity can occur and warrants discontinuation if transaminitis develops.

References

4
Research

Side effects of long-term glutamine supplementation.

JPEN. Journal of parenteral and enteral nutrition, 2013

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