While technically you could get too much vitamin B in your diet, its rare
However, glutathione levels are quickly depleted during viral infections
In the context of oral L-glutathione supplements, a true toxic overdose is highly uncommon for most healthy adults
(Bateman et al., 29423816) N-acetylcysteine can be used in patients with a history of anaphylactoid reactions (although it may be wise to initiate the infusion at a lower dose and pre-treat with antihistamines)
I know others have experienced it (you can read the super detailed review from one of my skincare heroines, fiftyshadesofsnail) but I use so many other treatments that I cant be definitive about it
This allows us to use advanced technologies (Class IV Laser, Neuro20, ExoMind) that insurance companies are typically 10-15 years behind in covering