The 48-year-old actor revealed to the Sun that he started using drugs from a young age emulating his father, Robert Downey. Sr - who was a frequent drug user, Contactmusic reported.
He feels that his life would have been easier if his dad had put firmer rules in place when he was a youngster. The star also credited his second wife, Susan Downey for getting his life back on track and encouraging him to create order and future plans.
The actor, who claimed that he started using marijuana at the age of six, has been drug free since 2003. He admitted that his addiction to substances meant his career took a back seat and he developed a negative attitude towards acting for some time.
Photos: Raveena Tandon, Sohail Khan at Marathi film 'Bhay' music launch
SRK-Gauri anniversary: B-Town stars and their non-filmi better halves
Birthday special: Popular mothers and daughters in Bollywood
Spotted: 'Kaabil' star Hrithik Roshan with dad Rakesh Roshan
'Rock On 2' trailer launch: Farhan, Shraddha enthrall audience with live gig