Intravenous Magnesium for Sickle Cell Vasoocclusive Crisis

Inclusion Criteria: * age 4-21 years, inclusive * Sickle cell anemia (Hb SS) or Sickle beta zero thalassemia disease (Hb Sβ°) * failed intravenous opioid pain management in the emergency department prior to the decision to admit the patient * admitted to the inpatient unit for sickle cell pain crisis Exclusion Criteria: * patient received more than 12 hours of intravenous pain medication prior to enrollment * previous enrollment in this study (only one admission per child is eligible) * history of allergy/intolerance to both intravenous morphine and hydromorphone * known other cause for pain (avascular necrosis, gall bladder disease, priapism, etc.) * patient with greater than 10 admissions for pain crisis in the past year * patient maintained on daily opioids or chronic transfusions for chronic sickle cell pain * transfusion within the previous two months * known kidney or liver failure (elevation of liver function tests does not warrant exclusion) * known pulmonary hypertension * pregnancy * diagnosis of bacterial infection, fever ≥39.5°C, acute chest syndrome, hemodynamic instability or sepsis * current oral magnesium supplementation or current enrollment in another therapeutic study protocol * previously diagnosed clinical stroke * current or planned use of neuromuscular blocker, nifedipine, ritodrine, or terbutaline * allergy to magnesium sulfate * discharge from an inpatient unit within 72 hours of arrival in the emergency department for the current pain crisis