The 45-year-old, who has won five Olympic Games gold medals, tells that the drugs took over his life after his career.
There were days when my son thought I would be found dead in the morning, says the Briton in an interview with The Observer.
I was a functioning addict. People didn't understand. But I was high on drugs most of the time.
Later this year, Wiggins will release an autobiography where he tells, in addition to his drug addiction, about his childhood traumas and his turbulent cycling career.
I feel lucky to still be here, he says.
The Briton was knighted after becoming the first cyclist to win Olympic Games gold and Tour de France, in 2012.
