I don't think there are any side effects, but in terms of benefits, I found this on a site: "Glutamine is a carbon and nitrogen donor and helps restore glycogen which restores energy. Glutamine is the most important component of muscle protein and helps repair and build muscle....Glutamine helps maintain cell volume and hydration, speeding up wound and burn healing and recovery...Glutamine benefits you by replenishing declining Glutamine levels during intense workouts....May help produce growth horomone levels....Glutamine may serve to boost your immune system....Glutamine is one of the most important nutrients for your intestines. It has the ability to 'repair a leaky gut' by maintaining the structural integrity of the bowels....It can also cure ulcers" As for that last thing about ulcers, I've found that chewable DGL licorice works better. Check out the link if you want to read other stuff they say about GLutamine: http://www.bodybuildingforyou.com/supplements-reviews/glutamine-side-effects-...
Or just do a google search for "bodybuilding and glutamine" or something like that.