Diclofenac potassium is a non-steroidal anti-inflammatory drug (NSAID) used to treat moderate pain, inflammation, and fever. While it is generally a safe medication, mild and serious side effects can occur. Patients taking this drug should follow some precautions in order to reduce their risk, and diclofenac potassium may not be appropriate for all patients. Diclofenac potassium is most frequently used for conditions in which the lining of the joints breaks down or swells, including osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis.

Another potentially serious side effect of diclofenac potassium is an increased risk of gastrointestinal problems, including holes in the stomach or intestine, ulcers, or bleeding. If experiencing stomach pain, severe vomiting or vomit that looks like coffee grounds, black tar-like stools, or blood in the vomit or stools, patients should seek immediate medical attention. People who have ever had ulcers or a bleeding stomach should discuss this with their doctors. Heavy alcohol consumption can also increase risk.

People who have asthma, lupus, liver disease, or kidney disease should discuss this with the prescribing doctor. Use of this medication is generally not recommended during pregnancy, particularly in the last few weeks of gestation, and women who are pregnant, trying to become pregnant, or nursing should speak to their doctors about this. Diclofenac potassium interacts with a number of medications, including blood thinners, steroids, diuretics, and other NSAIDs, so patients need to tell the prescribing doctor about all prescription and over the counter medications taken, including vitamins and supplements.