The 26-year-old is serving a 90-day court ordered rehab, as part of a plea deal in her lying to cops case, reported Radar Online.
"Lindsay advised Betty Ford that she wanted to invite a male friend, whom it's known she partied with for years and had provided drugs to her, including cocaine. He is a very, very, bad influence on her," a source said.
However, the treatment team looking after Lohan prohibited the dealer from visiting her.
"Lindsay was already livid that the doctors have taken away her Adderall. She thinks they are just out to get her and make an example out of her, because she is a celebrity. She hates being there and is counting the days until she will be released," the source added.