Inclusion Criteria:
* Subject is willing and able to give signed informed consent.
* Male and female patients aged 25 years or older.
* History of migraine for at least 12 months as diagnosed by the International Classification of Headache Disorders (ICHD-3).
* Chronic migraine for at least the previous 3 months prior to screening, as diagnosed by ICHD-3.
* Migraine preventative medications (including Botulinum toxin injections) are permitted if dose is stable for the 3 month period prior to randomization, and no change to dose is planned for the entire duration of the study.
* Using a reliable method of contraception for females of child-bearing age.
* Failure of at least 2 prior migraine preventatives, either due to lack of efficacy with an appropriate trial of the medication, or due to lack of tolerability.
* Able to follow study procedures, fill out headache diaries, and complete questionnaires.
* Completion of at least 90% of the headache diary during the one month baseline period.
Exclusion Criteria:
* Other active primary headaches, such as cluster headache, hemicrania continua, etc.
* Any secondary headache, such as headache related to intracranial hypertension, intracranial hypotension, hydrocephalus, intracranial mass lesion, etc.
* Pregnant, planning to become pregnant, or breastfeeding.
* Active or significant history of major mental illness, including severe depression, or anxiety, and any history of psychosis or schizophrenia.
* History of or current substance use disorder.
* Regular use of cannabis for medical or recreational reasons during the previous 12 months.
* History of significant cardiovascular or cerebrovascular disease, such as previous myocardial infarction, stroke, or peripheral vascular disease.
* History of hypertension greater than 160/100 and not medically treated.
* Any past history of seizure disorder.
* Liver disease or liver enzymes two or more times the upper limit of normal at baseline.
* Severe renal disease or GFR more than 30% below expected.
* Any disorder or condition leading to hypersomnolence or excessive daytime drowsiness, such as narcolepsy, excessive use of sedatives/hypnotics, etc.
* Any other medical condition that in the opinion of the investigators may pose a health risk to the subject if entered into the clinical trial.
* Use of interventions or devices, such as nerve blocks, sphenopalatine ganglion blocks, vagal nerve stimulators, and transcranial magnetic stimulators during the baseline period (weeks -4 to 0). These treatments will also be prohibited during the period of therapy (weeks 0 to 12).
* Use of transitional therapies such as a course of steroids or a dihydroergotamine protocol during the baseline period (weeks -4 to 0). These treatments will also be prohibited during the period of therapy (weeks 0 to 12).
* Overuse of triptan, dihydroergotamine, opioid, or barbiturate medications, defined as 10 or more days per month in the 3 months prior to randomization.
* Overuse of simple analgesics (such as acetaminophen, ibuprofen, aspirin), and non-steroidal anti-inflammatories (such as naproxen, ketorolac, diclofenac, etc.) defined as 15 or more days per month in the 3 months prior to randomization.
