Side Effects of L-Glutamine

Very few side effects of L-glutamine have been reported. It has been reported that L-glutamine supplementation may cause mania in people with bipolar disorder. There has also been one case of high liver enzymes possibly related to IV L-glutamine use. Although not very many L-glutamine side effects have been reported, the supplement could theoretically cause significant side effects.

Does L-Glutamine Cause Side Effects?

As with any medication or supplement, side effects are possible with L-glutamine (also known as glutamine). Many people assume that natural products (such as L-glutamine) are always free of side effects. However, this is simply not the case. It is reasonable to assume that any supplement potent enough to have medicinal properties may also have side effects. Although very few L-glutamine side effects have been reported, L-glutamine could theoretically cause significant side effects.
 

Reported Side Effects of L-Glutamine

In general, studies have reported no significant side effects with L-glutamine supplementation. There has been one case of high liver enzymes probably related to IV L-glutamine supplementation, and it has been reported that L-glutamine supplementation may cause mania in people with bipolar disorder (also known as manic depression).
 
Some people find the grittiness of L-glutamine powder to be rather unpleasant when taken orally. Trying different L-glutamine products may help with this problem.
 

Theoretical L-Glutamine Side Effects

There are some concerns that L-glutamine could cause some side effects based on how it works in the body. However, these theoretical L-glutamine side effects have not been shown to be a problem in humans. Since rapidly growing tumor cells use L-glutamine as a fuel, there is concern that L-glutamine may cause or worsen cancer (although studies have not shown this to be the case).
 
There is also concern that high doses of L-glutamine could cause effects in the brain (such as psychological problems) due to a buildup of glutamate and ammonia, since the body can break down L-glutamine into ammonia and glutamate. In theory, L-glutamine may also increase the risk of seizures.
 
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Written by/reviewed by: Kristi Monson, PharmD; Arthur Schoenstadt, MD
Last reviewed by: Kristi Monson, PharmD;
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