L-Glutamine Side Effects

Glutamine PowderL-glutamin, also known as simply glutamine, is an essential amino acid produced in the human body, and is essential for proper function of the immune system, brain, and digestive system. It is stored in both muscles and blood plasma, and is found mainly in skeletal muscle.

A powerful antioxidant found in foods such as barley, cabbage, corn, dairy products, meat and poultry, peanuts, dark green, leafy vegetables, and protein powders, L-glutamine can also be taken as a dietary supplement to increase muscle mass and enhance exercise performance in athletes, and is considered safe in the proper amounts. If this amino acid cannot be obtained through diet, supplements are usually taken during high-intensity workouts, or for conditions causing muscle wasting or low muscle mass. Receiving L-glutamine from food sources in not harmful to the body, but supplements should be taken under the supervision of a health professional.

  • L-glutamine can be used to treat some health conditions such as alcoholism, insomnia, HIV/AIDS, anxiety, and depression, as well as severe burns, treatment of colds/flu, or irritable bowel syndrome (IBS). Just as prescription drugs and other over-the-counter medications and supplements may present numerous sides effects to watch out for, this amino acid is no different. While L-glutamine can be beneficial in the proper doses and for certain conditions, too much of the amino acid can cause adverse reactions and side effects. The benefits of L-glutamine in the right amounts include:
  • Protection from diseases of the intestinal lining from NSAIDS or other medications
  • Protects the brain from ammonia toxicity
  • Provides energy to the brain
  • Elevates mood
  • Improves mental performance and long-term/short-term memory
  • Regulates protein synthesis
  • Stimulates growth hormones
  • Boosts the immune system

Here are the most frequently reported adverse side effects of overuse of L-glutamine:

Elevated Liver Enzymes/Brain Side Effects

Elevated liver enzymes signal liver toxicity due to the liver being unable to process the enzyme properly, causing excessive amounts of ammonia to accumulate in the blood system and brain. Recent studies have proven that an overabundance of L-glutamine, primarily from supplements, can cause injury to the brain. Patients with incidences of seizures, epilepsy, Alzheimer’s Disease, bipolar syndrome, and Lou Gehrig’s disease have been reported as having high L-glutamine levels in their brains, preventing mitochondria in the brain from producing energy, and should not take these supplements.

Stomach Distress

L-glutamine has been useful in the treatment of heartburn, and prevents stomach acid from irritating the digestive tract and esophagus. However, always take the suggested dosage of L-glutamine supplements, otherwise, too much can cause major stomach pain and cramping.

Kidney Malfunction

Since L-glutamine supplements cause a buildup of ammonia in the blood, supplements may cause Reye’s syndrome, kidney disease and failure, or cirrhosis of the liver, and the effects of any medications taken for these ailments can be lessened.

Pregnant/Breastfeeding Women

Studies are no conclusive as to whether or not L-glutamine has any adverse effects on pregnant or nursing women. However, as a preventative measure, these women should avoid taking supplements while pregnant or nursing.

Cancer Patients

L-glutamine has been known to reduce side effects and increase effectiveness of chemotherapy in those with colon cancer, and may prevent nerve damage caused by breast cancer medications. However, L-glutamine may stimulate the growth of tumors.


If a person is allergic to monosodium glutamate, then chance are that there will be a serious allergic response to L-glutamine supplements. Too much of this amino acid in
the body can interfere with the effects of seizure medications, chemotherapy, and Lactulose, which is used in the treatment of chronic constipation and hepatic disease.

General Side Effects:

Some side effects will require medical attention and some will not. The following are the most common and should go away on their own without calling a doctor:

  • Frequent bowel movements
  • Straining during bowel movements
  • Hoarseness or coughing

However, these side effects are less common, but more serious, and may require medical assistance:

  • Alteration in skin color, hives, itching, rash
  • Bacterial infections
  • Bad breath
  • Blood in urine, painful urination, decrease in amount of urine, dark urine
  • Bloody stool, diarrhea, constipation
  • Chills, fever
  • Cold extremities, shivering
  • Depression
  • Difficulty swallowing, shortness of breath, wheezing
  • Discoloration of fingernails or toenails
  • Dryness in mouth or sore throat
  • Excess thirst
  • Fainting, lightheadedness, dizziness, confusion
  • Flatulence
  • Insomnia, black circles under eyes, sunken eyes
  • Loss of appetite
  • Nausea, vomiting, vomiting of blood
  • Pain in lower back, side, stomach, or headache
  • Rapid heartbeat, tightness in chest, chest pain
  • Swelling around the eyes, face, lips, tongue, arms, or legs, or feeling bloated
  • Vaginal discharge or breast pain in females
  • Weakness, tiredness

Please remember that L-glutamine has many excellent benefits (read more on the benefits of L-Glutamine here) and is considered safe when receiving the nutrient through diet or as supplements given in the proper doses or under medical supervision. It can assist in controlling the symptoms of many illnesses and conditions. However, to avoid the side effects, it is always best to get advice from a health professional before taking an L-glutamine supplement to make sure that other medications or conditions do not exist that would be contradictory in its use. Do not hesitate to ask questions first before taking L-glutamine to remain healthy and happy!