Vaporized Cannabis for Chronic Pain Associated With Sickle Cell Disease

Inclusion Criteria: * Sickle cell disease, including sickle cell anemia (SS), sickle-hemoglobin C disease (SC), and sickle beta thalassemia disease (Sb). * Ongoing opioid analgesic therapy for chronic sickle cell disease-associated pain. * Subjects must be on a stable dose of analgesic medication (opioid or other) for at least 2 weeks before enrollment. * All men and women in this study must agree to use adequate birth control during this study. Acceptable barrier birth control methods are a male condom, female condom, diaphragm, or intra-uterine (IUD). * All women of reproductive potential (who have not reached menopause or undergone hysterectomy, oophorectomy, or tubal ligation) must have a negative urine b-HCG pregnancy test performed before initiating the protocol-specified medication. * Prior history of use of cannabis. Subjects must have smoked cannabis on at least 6 occasions in their lifetime prior to enrollment. * Subjects will self-report abstaining from smoking or ingesting cannabis for one week prior to their enrollment into the study. * Able to understand and follow the instructions of the investigator, including completing the pain intensity rating scales. * Karnofsky Performance Scale \>60. * Able and willing to provide informed consent. * Able and willing to spend two separate periods of 5 days and 4 nights in the Clinical Research Center at SFGH. Exclusion Criteria: * Severe coronary artery disease, uncontrolled hypertension, cardiac ventricular conduction abnormalities, orthostatic mean blood pressure drop greater than 24 mmHg, severe chronic obstructive pulmonary disease. * Evidence of clinically significant hepatic or renal dysfunction based on judgment of physician. * Positive serum THC level on Day 1 of study. * Active substance abuse (e.g., alcohol or injection drugs) as determined by urine toxicity screening. * Neurologic dysfunction or psychiatric disorder severe enough to interfere with assessment of pain or sensory systems. * Current use of smoked tobacco products. * Women who are pregnant or breast-feeding may not take part in this study. * Unable to read or speak English.