NAC is vital when clearing congestion from the lung when mucous is present. Yes, use it when sick but also for any lung issues including allergies, asthma etc.
Took this at a higher dose along with some other supplements for my PCOS. Helped me significantly and I definitely recommend.
I had read that NAC helps with lung function when sick, can remove mucous etc. Along with 10,000mg daily of Vitamin C plus 50,000 IU's daily of D and some zinc this patched the whole family right up!