That Stuff You Rub On Yourself 
(September 11, 2018)

Maybe that’s a bad title. This certainly isn’t going to be a comprehensive essay on ALL the different things that people rub on themselves for ALL different purposes. In fact, most of the musings that that last sentence gives rise to should maybe set aside as soon as possible, so let us continue apace.

Being as I am a doctor, what I will be discussing in the category of “stuff you rub on yourself” is stuff that is meant to relieve pain (or, “topical analgesics”). There seem to be about a million of these supposedly pain-relieving topicals available right now, both prescription and over-the-counter. So if you do not already have an ointment that you swear by, but are in the market for one, today’s essay may be somewhat useful to you.

To understand these things, we probably should look first at the different categories of active ingredients that one tends to find in the things.

The Counterirritants. This is stuff that makes your skin feel hot or cold, like menthol (cool). camphor (hot), eucalyptus and cinnamon oil. They work in two ways: 1) The irritation to the skin that they produce (yes, your skin gets irritated with you when you use these things, sometimes too much for people to use them at all) increases the blood flow to the area of application. That clears out any toxic byproducts in the area and relaxes the local muscles.

Also, the counterirritants 2) block pain by overloading the nerves in the area with sensation. You know how when you bang your elbow, you rub it and it doesn’t hurt as much? That is a real thing, and the counterirritants take advantage of that physiological trick. The sensation of vibration can block the sensation of pain, and something that irritates the skin will irritate ALL the nerves in the area. Since they are all talking at once, so to speak, the brain is overloaded and doesn't hear some of the pain signals. So it doesn't hurt as much. Cool, huh? Brains are SO smart.

The Salicylates. This is a class of anti-inflammatory chemicals that includes aspirin. Many people who can’t take aspirin can use a cream with a salicylate in it. They decrease pain by decreasing inflammation at the area of application.

NSAIDS. Mostly these are oral medications, like ibuprofen and naproxen. There are a couple of NSAIDs that can be use in topical analgesics like we are discussing, but they are only available in prescription form. Still, at least one of them (diclofenac) seems to work as well under some circumstances as the pills do, which is impressive for a topical. So if you can’t take NSAIDs, or you’d like a smaller dose, a gel with diclofenac in it might be helpful.

Lidocaine. Is a local anesthetic. It flat-out numbs out the nerves in the area that it is applied to.

Capsaicin. Is in a class all by itself. It irritates the skin and nerves like the counterirritants do. But it goes beyond that by (when used on a regular schedule) decreasing substance P in the area of use. Substance P is not just a great name for a band. It is also the source of a lot of chronic pain, especially in neuropathy. So especially if your pain is from neuropathy, a capsaicin topical might be worth a try.

The creams, gels, etc. out there for pain relief out there often contain more than one type of ingredient. For example, Bengay contains both salicylates and counterirritants. You have to try a few to see what works for you and what doesn't. And MAKE SURE YOU READ THE LABELS, both for ingredients and proper usage.

Aside from the active ingredients they contain, do we know anything else about pain relieving topicals? Well,  as for most things medical, evidence is limited, but "limited" doesn't mean that we don't know ANYTHING. The Cochrane Library is a place where you can find summaries of the state of the evidence on no end of medical subjects, and bless their nerdy little hearts, they did one last year on the available evidence on topical analgesics. Here’s what they concluded.

1) Topical analgesics work best on acute (short term) pain.
2) They work best in areas without a lot of soft tissue; meaning, where the bone is pretty close to the surface of the body, like fingers, wrists and knees. That’s simply because the ingredients are absorbed through the skin and don’t have to travel as far to get to the ouchie places.
3) Of all the carriers, gels worked best. Better than creams, sprays, oils, patches, etc.
4) The ingredients that worked the best for both sprain/strain type injuries, and for osteoarthritis as well, were the NSAIDs diclofenac and ketoprofen. Capsaicin got an honorable mention for its help in nerve pain like post-herpetic neuralgia and neuropathy, as I mentioned.

Now, if you are using something that the Lords of Evidence are currently sniffing at, that is no reason to stop using it. In fact, I would definitely NOT stop using it. Just because something doesn’t have a current Scientific Seal of Approval doesn’t mean that it doesn’t work, and more specifically, doesn’t mean that it doesn’t work for YOU.

Use these rules just to investigate the great unknown, just to guide you if you are in the market for a pain-relieving ointment. You’re also going to have to use what you know about yourself and what works for you to pick something helpful.

It's worth having something like this around. Something that you rub on a painful area to relieve pain can be very, very handy. With a topical analgesic, the effects are mostly limited to the area of application, so if for example your sensitive tummy doesn't usually allow you to take aspirin, you can probably use a rub with a salicylate without those problems and get some benefit that way. Or, you can avoid dousing your entire body with a pain reliever when you need it just on one area. And in the end, if a rub doesn’t work, you haven’t done yourself any real harm, a benefit that is underappreciated by most people until they become a medical statistic.

As usual, I have not given you enough information in this essay to decide whether or not a particular product is for you.  But you should have a little more knowledge of the subject now, enough to know better what you are looking at when you are squinting at the tiny print on a tube of Something at the drugstore. Knowledge is Power, after all.

--dr. diane holmes
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