Duloxetine for LBP

Inclusion Criteria: Present to Emergency Department (ED) primary for management of LBP, defined as pain originating between the lower border of the scapulae and the upper gluteal folds. Flank pain, that is pain originating from tissues lateral to the paraspinal muscles, will not be included. Musculoskeletal etiology of low back. Patients with non-musculoskeletal etiologies such as urinary tract infection, ovarian cysts, or influenza like illness will be excluded. The primary clinical diagnosis, at the conclusion of the ED visit, must be a diagnosis consistent with non-traumatic, non-radicular, musculoskeletal LBP. Patient is to be discharged home. Patients admitted to the hospital are more likely to be treated with parenteral medication and therefore are not appropriate for this study. Age 18-64 Enrollment will be limited to adults younger than 65 years because of the increased risk of adverse medication effects in older patients. Non-radicular pain. Patients will be excluded if the pain radiates below the gluteal folds in a radicular pattern. Pain duration <2 weeks (336 hours). Prior to the acute attack of LBP, back pain cannot occur more frequently than once per week. Functionally impairing back pain: A baseline score of > 5 on the Roland-Morris Disability Questionnaire Exclusion Criteria: Not available for follow-up Pregnant or breast-feeding Chronic pain syndrome defined as moderate or severe pain anywhere in their body on >50% of days for at least three months Allergic to or intolerant of investigational medications Contra-indications to non-steroidal anti-inflammatory drugs: history of hypersensitivity to NSAIDs or aspirin active or history of peptic ulcer disease, chronic dyspepsia, or active or history of gastrointestinal bleed Severe heart failure (NYHA 2 or worse) uncontrolled blood pressure (>160/100) Glomerular Filtration Rate (GFR_ <60ml/min Current use of anti-coagulants cirrhosis or acute hepatitis Contra-indication to duloxetine: alcohol use disorder chronic liver disease chronic kidney disease glaucoma Active use of medication for depression Score >4 on the Patient Health Questionnaire (PHQ-9) screening instrument or thoughts of suicide