Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) used to treat pain, inflammation, and swelling across a wide range of conditions. It comes in oral tablets, topical gels, liquid solutions, and even eye drops, with each form tailored to different problems. You may recognize it by brand names like Voltaren, Cambia, or Pennsaid.
Arthritis and Joint Pain
The most common reason people take diclofenac is arthritis. It’s approved for osteoarthritis, rheumatoid arthritis, and ankylosing spondylitis (a type of arthritis affecting the spine). For these conditions, diclofenac reduces joint pain, stiffness, and swelling, making daily movement easier. It doesn’t cure or slow the progression of arthritis, but it controls symptoms effectively enough to be one of the most widely prescribed NSAIDs worldwide.
If you have osteoarthritis in a specific joint like a knee, ankle, or hand, you can also use a topical gel instead of taking a pill. The over-the-counter 1% gel (sold as Voltaren Arthritis Pain) is applied up to four times daily on no more than two body areas at once. You squeeze a measured amount onto a dosing card included in the package, then spread it over the affected joint. It can take up to seven days of consistent use before you feel the full benefit. After applying, leave the skin uncovered for at least 10 minutes and avoid showering for at least an hour.
Acute Pain: Dental, Menstrual, and Muscular
Diclofenac works well for short bursts of acute pain. It’s commonly used for menstrual cramps, dental pain after procedures, muscle strains, and back pain. For these situations, the potassium salt form of diclofenac is preferred over the sodium form because it gets into your bloodstream much faster. Peak blood levels arrive within 30 to 54 minutes with diclofenac potassium, compared to two to four hours with the sodium version. That faster onset makes a real difference when you’re dealing with sudden, intense pain.
Over-the-counter diclofenac potassium products in some countries are approved for headache, dental pain, period pain, muscular pain, backache, and cold and flu symptoms including fever. These are intended for short-term use, typically no more than three days.
Migraine Attacks
Diclofenac potassium is FDA-approved for the acute treatment of migraine attacks, with or without aura, in adults 18 and older. A prescription oral powder (brand name Cambia) is mixed with water and taken at the onset of a migraine. It is not designed to prevent migraines or reduce how often they occur. It’s also not established as effective for cluster headaches, which are a different type of headache disorder.
Precancerous Skin Lesions
A lesser-known use of diclofenac is treating actinic keratoses, which are rough, scaly patches on the skin caused by years of sun exposure. These patches are considered precancerous because they can develop into skin cancer if left untreated. A prescription-strength topical gel is applied to the affected areas twice daily for 60 to 90 days. This is a completely different product from the arthritis gel sold over the counter, with a higher concentration of the active ingredient and a much longer treatment course.
How Diclofenac Compares to Ibuprofen
People often wonder how diclofenac stacks up against more familiar painkillers like ibuprofen. In studies of postoperative pain, 50 mg of diclofenac performed about the same as 400 mg of ibuprofen. A Cochrane review found that diclofenac 50 mg provided meaningful pain relief for roughly 1 in every 2.3 people who took it, while ibuprofen 400 mg achieved the same for about 1 in every 2.7 people. The difference is modest, but diclofenac is generally considered slightly more potent milligram for milligram. At 100 mg, diclofenac’s effectiveness improved further, helping about 1 in every 1.8 people.
Two Salt Forms, Different Speeds
Diclofenac comes in two chemical forms: the sodium salt and the potassium salt. They contain the same active molecule and ultimately do the same thing, but they enter your system at very different speeds. Diclofenac sodium is the original prescription formulation, typically sold as enteric-coated tablets designed to dissolve slowly and protect the stomach lining. This makes it a better fit for chronic conditions like arthritis where you’re taking it on a regular schedule two or three times a day.
Diclofenac potassium, on the other hand, absorbs roughly three to four times faster. That speed advantage matters most for one-off or intermittent pain, like a migraine or a toothache, where you want relief as quickly as possible. If you’re already taking diclofenac regularly on a set schedule, the difference between the two forms is minimal because your blood levels stay relatively steady either way.
Important Safety Considerations
Like all NSAIDs, diclofenac carries cardiovascular and gastrointestinal risks. It can increase the chance of heart attack or stroke, particularly with long-term use or in people who already have heart disease. It can also cause stomach ulcers and bleeding, sometimes without warning symptoms.
Diclofenac is harder on the liver than most other NSAIDs. People taking it long-term typically have their liver enzyme levels checked within the first four to eight weeks of treatment, then periodically after that. Signs of liver trouble include dark urine, abdominal pain, persistent nausea, or a skin rash. If these develop, the medication should be stopped.
People with advanced kidney disease should generally avoid diclofenac unless the benefits clearly outweigh the risk of further kidney damage. The drug can reduce blood flow to the kidneys, which is a concern with all NSAIDs but especially relevant for anyone whose kidney function is already compromised.
Topical formulations carry lower systemic risks than oral forms because less of the drug enters the bloodstream. That’s one reason the over-the-counter arthritis gel has become popular: it delivers the drug directly to the painful joint while limiting exposure to the rest of the body.