Yes, they are generally safe for long-term use when administered according to your healthcare provider's recommendations
With a pH of 1.5 or less, this acidic fire destroys the peptide bonds in reduced glutathione, disintegrating the molecule before it ever hits the intestines
Supplemental lipoic acid also decreased the serum concentrations of some (IFN-, ICAM-1, TGF-, IL-4), but not all markers (TNF-, IL-6, MMP-9), cytokines and other inflammation (98)
NAC appears to work through several overlapping mechanisms, including breaking disulfide bonds in mucus, influencing inflammatory signaling, supporting redox balance, and affecting glutamate activity in the brain.31 That helps explain why NAC has been studied across such different areas of health
"Folic Acid Fortification"
The lethal dose in humans would be approximately 21,000mg for a 70kg person, making the 1-3mg daily doses used in typical protocols extremely safe from a toxicity standpoint