"I am wondering if I should help her get a medical card as she struggles with social interactions. Is this a good idea to try this?"
Tourette’s syndrome (TS) is a complex neuropsychiatric disorder that manifests itself in vocal and motor tics, and may affect mood (anxiety) and behavior (obsessive-compulsive disorder). There are well-established medications for the treatment of TS; however, their efficacy varies from patient to patient.
If your sister has failed conventional therapy, she may benefit from cannabis. Several studies have been done that demonstrate patients have decreased severity and frequency of tics, an improvement in obsessive-compulsive disorder, and lessened anxiety.