Interesting discussion here.

I haven't tried NAC, but I have come across it during my research into some of the claims made around the treatment of Lyme disease using herbs and supplements. That's how I came here.

It seems that the goal of taking NAC is to aid glutathione production. Glutathione seems generally great. It is produced by your body - primarily the liver, I believe - and there's quite a lot of it in your body and it has lots of different roles, including in the immune system and as an antioxidant.

From what I read, there are mixed reports around whether taking glutathione orally is effective. I haven't done much research so far on NAC, but what I have found is the idea is that if you are lacking is cysteine (one of the precursors for glutathione), then supplementing it can help. What I read into this is that if you have adequate cysteine (which is obtained from protein containing food), then supplementing it may not help.

Glutathione decreases with age and also in certain conditions. I haven't found any studies yet assessing clinical impact of oral glutathione supplementation.

I've also been reading about the Th1/Th2 dynamic and its role in disease and found that diseases like asthma seem to be more Th2 dominant. Meanwhile, glutathione seems to be involved in more Th1 dynamic.. so it's curious that dixiemamma reports what she has here.

Not sure if that's helpful.

I've certainly found it useful to sift through and evaluate actual scientific studies, learning about the body systems via youtube etc. as I go along. I've found that some of the claims made online are based on very little evidence and of course there is a vested interest from supplement companies/manufacturers, who want people to believe their products are effective..

My approach has been to assess supplements for safety, cost and likelihood of being effective and take them based on that.

Haven't completed my assessment of NAC yet. May repost here when I do. It's certainly cheaper that glutathione!

I have no idea about long covid.

EDIT seems like there are contra-indications for some medications, so do check that out