L-Glutamine Side Effects

Updated February 21, 2017

L-glutamine (also commonly referred to simply as glutamine) is an amino acid that is naturally produced by the human body, and is found in both plasma and muscles. L-glutamine is also in a diverse array of foods, and is often taken as a dietary supplement. It is known to be beneficial for several different types of conditions, including insomnia, depression and anxiety. As with most medications and nutritional supplements, taking L-glutamine can lead to some side effects.

Rare Side Effects

Although there are no common side effects of L-glutamine, there have been rare instances of raised levels of liver enzymes due to taking this supplement. Also, for individuals suffering from bipolar disorder, it is possible that supplementing with L-glutamine could increase the risk of mania occurring. If you notice signs of either increased levels of liver enzymes or manic episodes while taking L-glutamine, you need to immediately consult your doctor.

Stomach Upset

L-glutamine is made naturally by the body, so if you take the supplement normally, you most likely will not experience any side effects. However, if you take L-glutamine in excess, you might experience stomach upset as a result. If you have an upset stomach while taking L-glutamine, you should cut down your intake of the supplement. Make sure to always take your recommended dosage amounts only, to be on the safe side.

Brain Effects

It is also believed that high dosages of L-glutamine could have certain effects on the brain (like psychological issues) because of the accumulation of ammonia and glutamate. This is because the body is capable of deconstructing and breaking down L-glutamine into both ammonia and glutamate. L-glutamine could also increase the chances of convulsions occurring.


L-glutamine is not appropriate or safe for everybody. You need to discuss L-glutamine with your doctor before taking it, particularly if you have epilepsy or seizures, bipolar disorder, serious liver disease or liver failure, have any allergies (particularly to monosodium glutamate, also known as MSG), or are pregnant, thinking about becoming pregnant, or nursing. L-glutamine might not be safe if any of these factors apply to you.

Drug Interactions

Drug interactions can potentially lead to decreased effectiveness in the medications or supplements that are involved. There are various medications that could cause interactions with L-glutamine, such as chemotherapy cancer treatment, seizure medicines and Lactulose. Be sure to speak with your doctor about any medicines or supplements that you are taking before starting L-glutamine.

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