It might be a red flag for me, depending on the illness.
Someone very close to me is involved with a man who is bi polar. His MEDS have a very adverse effect on him sometimes and he tires of the side effects so he's been known to 'go off' his MEDS.
There have been times when that happens that he is quite deranged, violent.
It's a sad situation as when he is medicated, he's a wonderful man. We just fear that one day that wonderful man will do something he can't take back.
So, I'd be weary of it for sure, based on my own personal experience.