The 1986 Argentina World Cup winner said his habit began in his early 20s and continued beyond the end of his career.
Maradona moved from Boca Juniors to Barcelona in 1982 before leaving the Camp Nou for Napoli two years later.
The 56-year-old also turned out for Sevilla, Newell’s Old Boys before ending his career at Boca in 1997.
“I was 24 when I started taking drugs. I was at Barcelona,” said Maradona in an interview with Canale 5. “It was the biggest mistake I've ever made in my life.
“My daughter asked me to live for her while I was in a coma. I thank God because he listened to her and woke me up.”
Maradona was asked whether money, women or drugs were the biggest problem in his career.
“Drugs were the biggest problem – drugs kill,” said Maradona.
“I'm very fortunate to be here speaking to you. If I had continued I would have died. No doubt."