I bought NAC on a 30 day supply one time only. because I was cautiously optimistic about this. I've tried all kinds of diets INCLUDING a pcos diet and nothing! I literally started NAC 2... DAYS... AGO!!! I already feel more normal and energetic then I've been in 2 YEARS! I deal with chronic migraines everyday that just wipe me. My daily mantra used to be " just go with your energy when you have it" I'd have to choose between daily activities. Today I could do everything I wanted to do! Amazing! I'm back today to put this stuff on autoship since I'm in the US.