That one side effect is mood swings, and they could be quite severe. For me it would have been best described as intolerance, impatient and generally grumpy and I could be quite short and sharp.
Time period: this really only was an issue when I first started low carbing, within the first month or so, pretty much under control immediately once I realised the cause.
The Cause: I was hungry, I had skipped a meal or was a few hours late, but because I didn't feel traditionally hungry I carried on without eating and I would end up quite grumpy and short with people.
The Remedy: eat something, it really was that simple, all I needed to do to resolve the mood was eat something and within 30 minutes a better frame of mind would be had.
For my lifestyle it is always lunch that can be a little tricky at times to have on a regular schedule, now I make an effort to ensure I do eat within 90 minutes of my regular lunch time, even if I am not all that hungry I try and eat a little of something.