Inclusion Criteria:

• 18 years to 75 years of age
• Onset of painful upper extremity tendonitis or bursitis, no more than 21 days prior to study entry
• Eligible diagnoses are rotator cuff tendonitis, bicipital tendonitis or subdeltoid/subacromial bursitis of the shoulder, medial or lateral epicondylitis of the elbow, and DeQuervain's tenosynovitis of the wrist
• Spontaneous pain with motion or resisted motion and tenderness to palpation over the involved tendon(s), bursa, or epicondyle
• Presence of pain of at least 5, with a maximum of 9, on an 11-point Numerical Rating Scale (NRS)

Exclusion Criteria:

• Aspirin, or short half-life NSAID use within 12 hours, or longer half-life NSAID use within 24 hours prior to study entry (see Appendix B: for table of NSAIDs)
• Opioid use within 3 days prior to study entry
• Topical treatment, other than local ice or heat, applied to the painful region within 3 days prior to study entry
• History of peptic ulcer disease within 1 year prior to study entry, any history of gastrointestinal bleeding, or coagulation disorder
• A history of, or evidence for underlying articular disease such as osteoarthritis, rheumatoid arthritis, gout, or pseudogout (calcium pyrophosphate deposition disease)
• Clinically significant and poorly controlled pulmonary, gastrointestinal, hepatic, renal, endocrine, or cardiovascular disease
• A history of hypersensitivity to diclofenac or diclofenac-containing products
• A history of intolerance to acetaminophen (rescue medication in this trial)
• A history of skin sensitivity to adhesives (e.g. adhesive tape)
• Pregnant or breastfeeding women and women of child-bearing potential not using effective means of contraception