Acute Low Back Pain. Topical Diclofenac and Oral Ibuprofen.

Inclusion Criteria:

• Present to Emergency Department (ED) primary for management of Low Back Pain (LBP),defined as pain originating between the lower border of the scapulae and the uppergluteal folds. Flank pain, that is pain originating from tissues lateral to theparaspinal muscles, will not be included.

• Musculoskeletal etiology of low back. Patients with non-musculoskeletal etiologiessuch as urinary tract infection, ovarian cysts, or influenza like illness will beexcluded. The primary clinical diagnosis, at the conclusion of the ED visit, must bea diagnosis consistent with non-traumatic, non-radicular, musculoskeletal LBP.

• Patient is to be discharged home.

• Age 18-69. Enrollment will be limited to adults younger than 70 years because of theincreased risk of adverse medication effects in the elderly.

• Non-radicular pain. Patients will be excluded if the pain radiates below the glutealfolds in a radicular pattern.

• Pain duration <2 weeks (336 hours).

• Prior to the acute attack of LBP, back pain must occur less frequently than once permonth.

• Non-traumatic LBP: no substantial and direct trauma to the back within the previousmonth

• Functionally impairing back pain: A baseline score of > 5 on the Roland-MorrisDisability Questionnaire

Exclusion Criteria:

• Not available for follow-up

• Pregnant

• Any analgesic medication use on a daily or near-daily basis

• Allergic to or intolerant of investigational medications

• Open wounds or skin breakdown of the lower back

• Contra-indications to investigational medications: 1) known peptic ulcer disease,chronic dyspepsia, or history of gastrointestinal bleed 2) Severe heart failure (NYHA 2 or worse) 3) Chronic kidney disease (GFR <60ml/min) 4) Current use ofanti-coagulants 5) cirrhosis (Child Pugh A or worse) or hepatitis (transaminases 2xthe upper limit of normal)