Lindsay Lohan's lawyer has shot down rumours the troubled actress has threatened to quit her court-ordered rehab stint if she is banned from taking her prescription medication.

The Mean Girls star is due to check into a treatment centre by 2 May (13) to begin a 90-day stay, but multiple reports have suggested the 26 year old is refusing to stop taking Adderall, a stimulant used to treat attention deficit hyperactivity disorder.

However, Lohan's attorney Mark Heller is adamant his client will be taking rehab seriously.

He tells the New York Post's gossip column Page Six, "She has not, nor would she be poised to, mandate any type of requirements. Nor has she directed me (to find a facility that permits) her to use any types of substances such as Adderall. She has to conform and comply with the (centre's) requirements."

Heller also dispelled speculation Lohan has already decided where she will undergo treatment, admitting the actress is considering five different clinics across the U.S.

He adds, "Lindsay is expected to sit with me this week... and then a final approval has to be rendered by the court."