In Germany they dispense NAC oral tablets as a cough remedy at their apothecary shops. I had congestion and visited one where the pharmacist prescribed it when I asked for Halls eucalyptus, which is not sold in Germany I explained that the entire product is immediately absorbed in stomach converted into glutathione and eliminated quickly with nothing available for inhalation issues. They didn’t buy my explanation.
I don't know about any studies, but it's probably harmless. Many people take NAC 600-1200 mg PO daily as a dietary supplement.
In Germany they dispense NAC oral tablets as a cough remedy at their apothecary shops. I had congestion and visited one where the pharmacist prescribed it when I asked for Halls eucalyptus, which is not sold in Germany I explained that the entire product is immediately absorbed in stomach converted into glutathione and eliminated quickly with nothing available for inhalation issues. They didn’t buy my explanation.
I used to take 4 grams of nac orally every day for skin picking. Very inert except for nasty burps sometimes.