"I'm back!" wrote the former Full House star. "Took a month to take care of things. Healthy. Feeling grateful for the love & support of family & friends."
In the accompanying photo, Stamos wears boxing tape around his hands and swings one fist towards a punching bag hanging from the ceiling. The actor has a determined look in his eye and is wearing a sweat-soaked "Win Blackie Win" shirt, a nod to his General Hospital character.
I’m back! Took a month to take care of things. Healthy. Feeling grateful for the love & support of family & friends. pic.twitter.com/enQ5D99nRG— John Stamos (@JohnStamos) July 24, 2015
PEOPLE confirmed on July 10 that Stamos had checked himself into a residential program for the treatment of substance abuse in late June.
The 51-year-old star was charged with a DUI on June 12, after which he was hospitalized briefly for an unknown medical condition.
Of the actor's decision to enter rehab, a source close to Stamos told PEOPLE that he is "focusing on his health" and "knows he needs to take care of himself."
Stamos is set to star in a highly anticipated Netflix reboot of Full House, titled Fuller House, a 13-episode series that will stream on Netflix next year.
The cast of Fuller House is already back at work, and costar Candace Cameron-Bure told Entertainment Tonight on July 16 that "everything's great with the show. [Stamos] will be there."