The Two And A Half Men star, who has endured a similar battle to Lohan, said it is difficult to overcome problems when you are in the public eye so much.
The 45-year-old spent time in rehab in February this year and received a further 30-day treatment order in August. He told Radar Online, 'I think she's doing the best she can. It's not easy to begin with, but then you put it under the bright lights of this circus and it makes it that much more difficult.
'People just need to leave her alone and let her do her thing.
'I think at the end of the day she'll win.'
The actress is believed to have entered the Betty Ford Centre on Monday after failing two court-ordered drug tests earlier in the month.