i had herx like reactions to it when taken orally at high doses
this was in an attempt to get to "bowel tolerance" as is often advised by more integrative doctors
i had to bail at around 25-30g a day orally of pure ascorbic acid - did not have loose stools even at that dose
oral bioavailability is tightly regulated by mechanisms in the gut lining - after around 2g a day i think - the absorption levels off regardless of increasing dose https://pubmed.ncbi.nlm.nih.gov/15068981/
at the time it made me think that the herx like effect was largely likely due to killing gut bacteria rather than systemic effects.
a few other things that act only on the gut have done this to me - and strengthened my belief that this can be the case in lyme et al - when the immune system is highly dysregulated.