Wendy Haaf answers your questions about health, nutrition, and well-being.
Do topical creams containing non-steroidal antiinflammatory drugs (NSAIDs) actually help relieve pain? I have a hard time believing they’re effective. Isn’t our skin designed to keep anything from passing through?
Unlike many over-the-counter (OTC) products, topical NSAIDs are backed by solid scientific evidence. In Canada, diclofenac is the NSAID available in topical form, and it comes in two strengths: over-the-counter (trade name: Voltaren) and prescription (trade name: Pennsaid).
The two OTC oral NSAID options available in Canada are ibuprofen (Advil) and naproxen (Aleve). “There are a few meta-analyses and studies that show that topical NSAIDs provide relief similar to that of oral NSAIDs [for certain types of localized pain],” explains Naomi Steenhof, a pharmacist and assistant professor in the University of Toronto’s Leslie Dan Faculty of Pharmacy.
“We see benefit for both pain and function.” In particular, she says, “there have been some good studies showing that they work about as well for osteoarthritis in the knees and fingers.” On the other hand, she adds, “the evidence isn’t there in the same way for the hip.”
This is probably because the hip lies deeper within the body and the medication is less likely to penetrate that far. (Topical NSAIDs do indeed pass through the skin barrier—we’ll explain how in a moment.)
The major advantage of topical NSAIDs over oral formulations is that they provide a similar level of relief at a much lower dose. The former is therefore much safer for people who aren’t good candidates for oral NSAIDs because of a higher risk for complications such as internal bleeding, heart attack, or kidney failure due to a chronic medical condition. “The big ones are heart disease, ulcers, uncontrolled high blood pressure, and chronic kidney disease,” Steenhof says.
When used as directed, topical NSAIDs are unlikely to cause side effects, though they can occur; they include dry skin, rash, and sun sensitivity.
So how does diclofenac get past the skin barrier? “Your skin is good at keeping things out, but it’s not perfectly sealed like a brick wall,” Steenhof says. Instead, the “mortar” between the cells is fat, and “diclofenac is a bit fat-soluble, so it can slip through,” she explains. The drug-delivery formulation—called an emulgel (from “emulsion” and “gel”)—aids in this process. Prescription diclofenac gel contains something called an enhancer, which slightly disrupts the skin barrier and “helps more of the drug get through,” Steenhof says. The OTC variety is applied four times a day, versus twice a day for prescription-strength.
If you’re thinking of trying a topical NSAID, you should know that one application isn’t nearly enough of a sample for you to decide whether it’s working. “You want to use it the recommended two to four times a day consistently for a week or two, because what it’s doing is reducing inflammation, which can take a few days,” Steenhof advises.
Overall, when it comes to allowing you to move more—movement being the best medicine for knee osteoarthritis—Steenhof says, “topical NSAIDs can be a nice option.”
