Diclo-Gel is a topical gel containing 1% diclofenac sodium indicated for rheumatoid arthritis and osteoarthritis. It works rapidly to relieve pain by inhibiting the cyclooxygenase enzyme and reducing prostaglandin formation. A comparative study found Diclo-Gel has a more rapid onset of action and lower risk of side effects than other similar products. Common side effects may include allergic reactions, irregular heartbeat, and gastrointestinal issues.