Using the Flector Diclofenac Patch for Knee Pain


Many patients like to use skin patches for osteoarthritis knee pain. One such option is the Flector patch, which delivers a pain-relieving nonsteroidal anti-inflammatory drug (NSAID) to the sore knee for twelve hours at a time.


What It Does

The Flector patch is a topical formulation available as a skin patch that contains 1.3% diclofenac epolamine, an NSAID. The patch, which measures approximately 4 inches by 5.5 inches, is an alternative to the oral formulation of diclofenac (Voltaren) and the topical gel formulation (Voltaren gel).

The Flector patch was approved by the Food and Drug Administration in 2007, and it is marketed in the United States by Alpharma. It has been available in Switzerland since 1993 and is approved in over three dozen countries.


The Flector patch was approved to treat acute pain due to minor strains, sprains, and contusions. It is primarily recommended for and used by patients who cannot tolerate oral diclofenac. One Flector patch should be applied twice daily (every twelve hours).

Studies have shown that topical diclofenac formulations (gels, patches, or plasters) are superior or equivalent to oral diclofenac formulations. A 2017 review of studies concluded that topical diclofenac is as effective for the treatment of osteoarthritis and musculoskeletal injuries as oral NSAIDs, with minimal side effects.

The 2019 American College of Rheumatology/Arthritis Foundation guidelines for osteoarthritis treatment give topical NSAIDs like Flector a “strong” recommendation for knee arthritis and a “conditional” recommendation for hand and hip arthritis. They recommend using them prior to trying oral NSAIDs.

Who Should Not Use the Flector Patch

The Flector patch is not an appropriate treatment for everyone. The patch should not be used by:

  • Patients allergic to diclofenac, aspirin, or other NSAIDs
  • Patients who just had or will be having a coronary artery bypass graft

The Flector patches have the same warnings that the pills do, with labels listing the cardiovascular and gastrointestinal risks common to NSAIDs. Using the patch and the oral medication at the same time may increase adverse effects associated with NSAIDs.

You should not use any lotions or cosmetics on the same site that you are applying the Flector patch, not even sunscreen. They could affect absorption and reduce how well you tolerate the patch medication.

Studies haven’t yet established whether the patch is safe for effective for children. The testing didn’t include enough subjects over age 65 to understand if it might have a different response in younger patients.

Nonformulary Treatment

Some insurance companies list diclofenac patches as “nonpreferred” and “nonformulary.” The diclofenac patch is expensive compared to its oral counterpart. Insurance companies would prefer you use something less expensive but just as effective. Patients who cannot use the cheaper alternatives are appropriate candidates for the diclofenac patch.

Possible Side Effects

Signs of an allergic reaction—including hives and the swelling of the face, lips, tongue, and throat—require emergency assistance. Otherwise, the risk of serious side effects is low for the diclofenac patch.

The drug label says to stop using the patch and contact your healthcare provider right away if you experience these side effects:

  • Nausea
  • Fatigue or weakness
  • Itching
  • Yellow eyes or skin
  • Stomach pain
  • Flu-like symptoms
  • Vomiting blood
  • Bloody, black, or tarry stool
  • Unusual weight gain
  • Skin rash or blisters with fever
  • Swelling of the arms and legs, hands and feet

Drug Interactions

Certain drugs that you may already be taking can interact with the Flector (diclofenac) patch, such as Coumadin (warfarim), digoxin, pemetrexed, cyclosporine, lithium, methotrexate, diuretics, steroids, and ACE inhibitors.

Bottom Line

While the Flector patch is not for everyone, it may be an option for you. Consult with your healthcare provider and discuss all of your treatment options.

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