How does one become an Illinois Medical Cannabis Caregiver? Patients under the age of 18 or those who are unable to manage the use of medical cannabis themselves may select a designated caregiver to assist with the patient’s use of medical cannabis. Minors will need certification from two (2) physicians. Patients under the age of 18 may have two designated caregivers, if both are parents or legal guardians with significant responsibilities for the patient. Designated caregivers must be 21 years of age or older. Caregivers must apply for a Registry ID Card online through the state of Illinois’ online application portal or by completing and submitting a printed application available online, which is available here. The application process and requirements for designated caregivers is similar to that of patients applying for a medical marijuana card for themselves.Registry ID Cards for designated caregivers are valid for 3 years and cost $75 if applied for at the same time as the patient and $100 if applied for separately. A patient’s designated caregiver may purchase and possess up to 2.5 ounces of medical cannabis from a state-licensed dispensaries. A patient and his or her designated caregiver are prohibited from purchasing (collectively) more than 2.5 ounces of medical cannabis during any two week period, unless they have a waiver stating otherwise.