IV Acetaminophen as Adjuvant Analgesic to Hydromorphone - Emergency Department Patients

Inclusion Criteria

• Pain with onset within 7 days of the ED visit
• ED attending physician's judgment that the patient's pain warrants IV opioids.
• ED attending physician's judgment that the patient has capacity to provide informed consent.
• ED attending physician's judgement that patient is not a chronic user of opioids or acetaminophen
• Patients must be able to understand English or Spanish.

Exclusion Criteria

• Use of opioids or tramadol within past 24 hours.
• Use of acetaminophen or non-steroidal anti-inflammatory medication within the previous 8 hours.
• Prior adverse reaction to opioids or acetaminophen.
• Chronic pain syndrome: frequently recurrent or daily pain for at least 3 months; examples of chronic pain syndromes include sickle cell anemia, osteoarthritis, fibromyalgia, and peripheral neuropathies.
• Medical condition that might affect metabolism or opioid analgesics or acetaminophen such as hepatitis, renal insufficiency or failure, hypo- or hyper-thyroidism, Addison's or Cushing's disease
• Pregnant or breastfeeding
• Alcohol intoxication: the presence of alcohol intoxication as judged by the treating physician or nurse
• Not at risk of suicide assessed by triage nurse
• Systolic blood pressure <100 mmHg
• Heart Rate < 60/min
• Oxygen saturation < 95% on room air:
• Use of monoamine oxidase (MAO) inhibitors in past 30 days
• Use of transdermal pain patches
• Taking any medication that might interact with one of the study medications, such as a selective serotonin reuptake inhibitor (SSRI) or tricyclic anti-depressants, antipsychotics, anti-malarial medications (quinidine or halofantrine), amiodarone or dronedarone, diphenhydramine, celecoxib, ranitidine, cimetidine, ritonavir, terbinafine or St. John's Wort.
• Patients who have been previously enrolled in this same study