Lou Reed Back at Home After Medical Emergency -- 'He's Fine'

Lou Reed's fresh liver landed him in the ER Sunday ... but we're told he's back home and doing fine.

The 71-year-old rock legend was rushed to the hospital after he became sick to his stomach and repeatedly threw up ... that's what our sources are telling us.

EMTs were called and declared a medical emergency, because Reed had a liver transplant 2 months ago and they feared rejection -- who doesn't.