Police were called by London Ambulance Service to the scene of a collapsed male shortly after 2315hrs on Saturday, 25 July at Wolvercote Road, SE2.
At the scene officers found an 18-year old man in cardiac arrest.
He was taken to a south London hospital in a critical condition and was pronounced dead at 0130hrs this morning, 26 July.
Next of kin have been notified. A post-mortem will be scheduled in due course.
At this stage the death is being treated as unexplained pending the findings of the post-mortem.
Bexley Police investigate.