How Topical Analgesics Relieve Pain


A recent conversation with a most lovely client of mine gave me the idea for this week’s post. It addresses something I am asked about quite often: why do topical analgesics make your muscle pain feel better?

You all know what I’m talking about: those warming/cooling/tingly gels and creams you rub on achey body parts when you are desperate for some pain relief. The one I use is called Sombra. Biofreeze is another popular one but there are many to choose from on the market. I’ll discuss Sombra, because that is the one I am familiar with and get results from.

It doesn’t “cure” the source of the pain, but it does make you feel better when rubbed onto the skin. So, what’s the deal?

The answer to that is actually nifty little biological trick and one of my favorite body factoids. The main ingredients in Sombra that contribute to the relief it gives are: Camphor, Menthol and Capsaicin. And basically these guys work by playing tricks on your brain.

Camphor and Menthol, which are the main ingredients act as “counterirritants” and are what create that tingly, cooling sensation on your skin. This sensation (which depending on your sensitivity levels – can be quite strong) basically gets to your brain faster and distracts it from the pain sensations in your muscles. Kind of like punching someone in the arm to help their headache, only not as mean.

The third ingredient, Capsaicin, is actually the chemical found in chili peppers that burns your mouth and leave the kitchen staff at Indian restaurants snickering at you from the doorway. Amateur. But it also messes with the way your brain receives pain signals.

First you need to know that pain is classified into two different types: “good pain” and “bad pain.” Good pain is that immediate and sharp sensation that screams to your brain: “Hey idiot, that burner is on MOVE YOUR HAND!” Bad pain is chronic pain, as in: “Dude, seriously? You’ve been hunched over that computer for TWELVE HOURS, I will make you pay for this all week.” Two different kinds of pain and they are transmitted to the brain via two different kinds of nerves. The nerves that send good pain signals are fast and the nerves that send bad pain signals are slow and last longer.

In comes Capsaicin which through some freaky science-y magic binds to certain nerve receptors responsible for passing bad pain signals and causes them to dump off all of their “Substance P” (which is the pain chemical – signal – that the nerves are passing up to the brain.) Once the nerves are forced to all at once dump their supply of Substance P, they are temporarily unable to make more  and voila: no pain signals to send!

So to recap, Topical analgesics (in this case Sombra) basically play tricks on the way your body perceives pain signals by first sending faster  skin pain sensations (tingly, light burning) that distract your brain from the deeper muscle pain sensations and second through the chemical Capsaicin which temporarily alters the nerves responsible for sending slow, chronic pain signals to the brain by depleting them of the chemical that contains those pain sensations.  Pretty nifty, huh?

Now here’s the rub: it doesn’t last. And that is why it doesn’t cure he pain. If those slow, achey pain signals are from overwrought muscles full of tension and trigger points then you can bet that as soon as all of those distracting sensations subside and those slow pain nerves can start producing Substance P again your muscles will still be screaming at your brain only now it’ll hear them.

But for temporary pain relief and to take the edge off of chronic muscle soreness give it a try! But whatever you do don’t go rubbing chili peppers all over your skin. And don’t say to the waitress with a nonchalant shrug “you know, pretty spicy” when she asks how you like it. You’ll be sorry.

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