Police say Weston’s body was found in his north London home on Tuesday after neighbours raised the alarm.
His death was not being treated as suspicious, officers said.
An autopsy revealed the causes of death as gastric intestinal haemorrhage, cirrhosis of the liver and throat problems.
Weston joined Fleetwood Mac in 1972 as replacement for Danny Kirwan, and played on the band’s albums Penguin and Mystery to Me.
His signature slide guitar sound can be heard on the Penguin track Remember Me, and he also wrote the record’s instrumental closer, Caught in the Rain.
But during an American tour the next year, Mick Fleetwood discovered Weston was having an affair with his wife, Jenny Boyd. Weston was fired.
He released several solo albums and recorded with musicians including Long John Baldry, Murray Head and Steve Marriott.
One of his later solo projects would feature the drumming of his former bandmate Mick Fleetwood, an indication that the pair had buried the hatchet.