Michael Douglas found his son's drug addiction and incarceration ''very painful and difficult''.

The 'Ant Man and the Wasp' star's offspring, Cameron Douglas - whose mother is the 'Wall Street' actor's first wife Diandra - was jailed for drug possession in 2010 and had his sentence almost doubled in 2011 after he was found trying to sell prescription pills to other inmates but was released in 2016 following lengthy stints in solitary confinement and Michael is pleased he has finally turned his life around.

He told Radio Times magazine: ''My son's struggle was a nightmare. It was stressful for all involved, very painful and difficult.

''He has been out of prison a year and a half and he is actively pursuing his career.

''I am happy to say he is in wonderful shape now.''

And the 73-year-old star - who also has Dylan, 17, and 15-year-old Carys with wife Catherine Zeta-Jones - is pleased with how his own life has turned out.

He added: ''I'm a happy camper.''

Michael became a grandfather in December when Cameron and his girlfriend Viviane Thibes welcomed daughter Lua into the world, and though he thinks it's ''great'', he isn't enjoying it as much as he'd hoped to because he's still got his youngest child living at home so can't appreciate having a youngster around in the way some other grandparents can.

He told reporters: ''It's great. I mean, not as much as I had hoped because I still got a kid in the house.

''I think you appreciate being a grandparent when everyone is out of the house and it's empty-nest syndrome, but I still have my daughter with me.''