The 'Scary Movie V' star, who is set to complete her 90-days of court-ordered treatment on July 31, which is part of a plea deal she struck to avoid jail after lying to police officers about driving during a car accident last year, celebrated her 27th birthday at Cliffside Rehab Centre in Malibu, California,and was given special permission to access her social media profile for the first time.
The actress took advantage of her rare opportunity to be allowed to use the Internet and thanked her fans for their supportive messages.
She wrote: "Reading your #happybdaylilo tweets. These are awesome! Thank you guys. Happy bday July babies!"
Lindsay also sent short messages to two fans, as well as an orphanage, and retweeted a collage made by one of her biggest fans, adding: "Before I go. Thanks @LOHANTHONY"
The messages mark the first time the actress has been on Twitter since entering rehab in May but a member of her team has tweeted a few times on her behalf to promote her movie 'The Canyons' and also to extend her sympathy to James Gandolfini's family following his recent death.
The 'Mean Girls' star reportedly "didn't like" celebrating her birthday in rehab but "made the most of it" by sharing cake and ice-cream with other patients and her lawyer, Shawn Holley.
A source previously revealed that she plans to host another small party with her family, as it is visiting day.