Hi. I took 2400mg of NAC for 3.5 weeks without any symptoms, flu like or other. Then WHAM. I got the mac daddy of colds (and in the summer). Major runny nose, sneezy, congestion....but no fever of any kind. The last time I had a cold was 6 years ago. Could this have been a delayed NAC flu reaction? I ask, because it seems like most people noticed symptoms almost immediately after taking NAC. It took me several weeks, and it's possible it was just a legimate (and long overdue) cold.