We are 3 days in (at 300 MG NAC, doctor wants us to go to 900), so far it has been ok. We have been treating MTHFR for about a month. I don't want to jinx myself but these supplements have really been helping, I feel DD is pretty close to her normal self and her Lyme pain is GETTING BETTER :) Also she had a red rash on her bottom area that is gone, I suspect now that was from yeast which we have been treating with Enhansa. I'm going to go a few more days at 300 and then try 600. I am going to ramp up over 3 weeks.