DICLOFENAC SODIUM (VOLTAREN GEL)

What is diclofenac?

Diclofenac sodium or Voltaren gel is a non-steroidal anti-inflammatory drug (NSAID) that was previously only available as a prescription medication but is now available over the counter. It is a topical gel formulation that can be applied to joints such as the knees, ankles, feet, elbows, and wrists to relieve pain from arthritis and osteoarthritis.

It is important to apply a sufficient amount to the affected joint to reach its full effectiveness. For lower extremities, 4 g can be used for each affected area up to four times daily with a maximum dose of 16 g per joint. For upper extremities, 2 g can be applied to each affected area up to 4 times a day for a maximum dose of 8 g per joint. The maximum total body dose for all combined joints should be 32 g daily. A dosing card on the product’s box should be used when applying this medication.

How can diclofenac help alleviate certain long COVID symptoms? 

Diclofenac works by reversibly inhibiting enzymes in our body called COX-1 and COX-2 that help reduce pain and inflammation topically. It is also believed to reduce pro-inflammatory substances called cytokines and inhibit the activation of other immune cells that can cause inflammation.

The prevalence of post-COVID pain is estimated to be up to 63.3%, and patients with chronic pain can have exacerbated symptoms after COVID.¹ Multiple possible mechanisms behind post-COVID pain exist. The virus may cause pain by entering and attacking musculoskeletal and nervous systems, including the brain. Persistent inflammation from overactivated inflammatory pathways and excessive activation of blood clotting can also contribute to pain.

COVID can cause various types of pain, such as headaches, neuropathic pain, musculoskeletal pain, and fibromyalgia. Inflammatory arthritis has also been reported in post-COVID patients, with symptoms similar to rheumatoid arthritis (RA) that commonly affects the knee, ankle, and wrist.² Diclofenac is specifically useful in cases of inflammatory arthritis or musculoskeletal pain focused on the joints post-COVID.

What evidence supports diclofenac’s use for long COVID?

Early on in the pandemic, anecdotal reports suggested that NSAIDs could potentially increase susceptibility to COVID due to their ability to increase expression of ACE2 receptors that are targeted by the SARS-CoV-2 virus.³ However, several studies have since debunked this theory and have shown that the use of NSAIDs is not associated with increased COVID severity or risk of all-cause mortality.⁴

A survey of 696 COVID patients in Italy reported that common analgesics such as ibuprofen temporarily reduced pain severity in the post-acute phase of COVID.⁵ More studies are needed, specifically investigating the use of the NSAID diclofenac for post-COVID pain. Still, diclofenac has been shown to effectively relieve joint pain and is a reasonable option to consider for post-COVID symptoms like inflammatory arthritis. Chronic use of NSAIDs, however, should be discussed with a healthcare provider. 

What are some things to watch out for with diclofenac?

Because Voltaren gel is a topical NSAID, it has a better safety profile than other oral NSAIDs with limited absorption into the body. Some side effects can include skin irritation or itching, skin dryness or redness, and numbness or tingling.

References:

1)      El-Tallawy SN, Perglozzi JV, Ahmed RS, Kaki AM, Nagiub MS, LeQuang JK, Hadarah MM. Pain Management in the Post-COVID Era-An Update: A Narrative Review. Pain Ther. 2023 Apr;12(2):423-448. doi: 10.1007/s40122-023-00486-1

2)      Ciaffi J, Vanni E, Mancarella L, Brusi V, Lisi L, Pignatti F, Naldi S, Assirelli E, Neri S, Reta M, Faldini C, Ursini F. Post-Acute COVID-19 Joint Pain and New Onset of Rheumatic Musculoskeletal Diseases: A Systematic Review. Diagnostics (Basel). 2023 May 25;13(11):1850. doi: 10.3390/diagnostics13111850

3)      Kushner, P., McCarberg, B.H., Grange, L. et al. The use of non-steroidal anti-inflammatory drugs (NSAIDs) in COVID-19. npj Prim. Care Respir. Med. 32, 35 (2022). doi: 10.1038/s41533-022-00300-z

4)      Reese JT, Coleman B, Chan L, Blau H, Callahan TJ, Cappelletti L, Fontana T, Bradwell KR, Harris NL, Casiraghi E, Valentini G, Karlebach G, Deer R, McMurry JA, Haendel MA, Chute CG, Pfaff E, Moffitt R, Spratt H, Singh J, Mungall CJ, Williams AE, Robinson PN. NSAID use and clinical outcomes in COVID-19 patients: A 38-center retrospective cohort study. medRxiv [Preprint]. 2021 Dec 22:2021.04.13.21255438. doi: 10.1101/2021.04.13.21255438

5)    Galluzzo V, Zazzara MB, Ciciarello F, Tosato M, Bizzarro A, Paglionico A, Varriano V, Gremese E, Calvani R, Landi F on behalf of Gemelli against COVID-19 Post-Acute Care Team. Use of First-Line Oral Analgesics during and after COVID-19: Results from a Survey on a Sample of Italian 696 COVID-19 Survivors with Post-Acute Symptoms. J Clin Med. 2023; 12(8):2992. https://www.mdpi.com/2077-0383/12/8/2992