L-Glutamine

Glutamine

Snapshot

Indications	Contraindications
Radiation oral mucositis¹ Chemotherapy-related diarrhea² Postinfectious irritable bowel syndrome³ Intestinal permeability^4–6 Muscle wasting in catabolic states⁷ Perioperative colorectal surgery⁸	Advanced cirrhosis⁹ Critical illness, multiorgan failure¹⁰

L-glutamine is a conditionally essential amino acid that fuels rapidly dividing intestinal and immune cells, and plasma levels fall with illness, intense exercise, and malnutrition¹¹. Supplementation is used to support the intestinal barrier, to limit mucositis and diarrhea during cancer therapy, and to preserve muscle in catabolic states. Typical patients have postinfectious gut symptoms or are receiving radiation or chemotherapy.

In critical illness, a meta-analysis of enteral trials found no mortality benefit¹². About nine thousand products list L-glutamine, mostly powders and capsules; see Form comparison.

The cirrhosis caution exists because glutamine is metabolized to ammonia, which can overwhelm hepatic clearance and worsen encephalopathy, though LiverTox rates it an unlikely cause of acute liver injury⁹. Health Canada labels ask for a practitioner's advice before use in pregnancy or breastfeeding¹³.

Last updated October 16, 2026. Read how we make monographs.

In the full monograph

72 sources, 57 studies

When to useThe situations practitioners use it for, each with the reason and the study behind it.
SafetyWho should avoid it, who needs extra care, and the side effects reported in studies.
InteractionsThe medicines and supplements it interacts with, the effect of each, and what labeling says to watch.
Protocol notesThe doses used in studies, how and when they were taken, and how the forms on the market compare.
How it worksWhat it is and how it works in the body, in plain terms.
Published studiesThe studies behind each use, popular claims checked against them, and trials still under way.
Word of mouthWhat patients and practitioners report online, kept separate from the clinical evidence.
Clinical perspectiveA closing read of where the evidence is solid, where it is thin, and what has not been studied.

Snapshot

In the full monograph

Sources