Diclofenac is classified as a nonsteroidal, anti-inflammatory drug that treats pain, tenderness, swelling and stillness that comes with osteoarthritis, rheumatoid arthritis or ankylosing spondylitis. Many people recognize it under the brand names of Cataflam, Voltaren and Zipsor. These brands also typically treat pain from menstrual cramps and other sources, while gel and cream forms treat keratosis, according to Live Science.
Live Science notes that diclofenac comes in various forms including capsules, liquid-filled capsules, powder for solution, enteric-coated tablets, extended-release tablets and plain tablets. In addition to gels and creams, it also comes in other topical forms including extended-release patches and solutions. Diclofenac taken orally usually has mild side effects such as bloating or gas, constipation, diarrhea, dizziness, headache and ringing in the ears.
MedlinePlus also warns of mild side effects with gel or cream forms including acne, constipation, dizziness, gas and stomach pain. Gel side effects also include dryness, hardness, irritation, itching, numbness, redness, scaling or swelling at the site of application. A burning, numbness or tingling in the arms, feet, hands or legs may also occur. Both oral and gel or cream diclofenac risk more severe side effects that warrant a visit to a physician and suspension of use.