Deja vu all over again. 
I’m curious what @Qadgop_the_Mercotan says, but my understanding is that when you absorb something through your skin, some of it always dissolves into the whole body, so to speak, and some of it stays more local. The more central the location and the better its blood supply, the more gets into the whole body and the less stays put, so to speak.
I use an estrogen patch, which is supposed to supply a systemic dose of estrogen. But there’s more locally. I can see the effect on the skin immediately under it, and you are supposed to move it from place to place. Also, the instructions both tell you where to put it, and also, where not to put it. You aren’t supposed to put it on the breasts because they are specifically sensitive to estrogen, and too much increases your risk of breast cancer. The goal is to get enough in the rest of the body without too much in the breasts.
Some topical medicines really work mostly “right where you put them”, like a cream you put on a rash. Others, like
topical diclofenac gel seem iffier. But maybe if i put it on the skin of my foot the foot really does get a significantly higher dose than the rest of my body. The foot is relatively remote and has a so-so blood supply.
I’m sure it also varies from person to person.
FWIW Cochrane’s take:
Topical nonsteroidal anti-inflammatory drugs for chronic musculoskeletal pain in adults | Cochrane.
The oral mucosa is VERY vascular, and as a result, meds are absorbed there about 20 times better than thru the skin, and also enter the general circulation more quickly and in far greater amounts than via the skin.
Yeah, vascular. That’s the word i couldn’t think of.
Anal mucosa is also very vascular, hence an acetaminophen formulation given per rectum and diazepam for home emergency seizure use, among others.
I looked at the ingredients. It’s basically Ben-Gay, packaged for horses.
If it works for you, use it!
I got some Voltaren gel when it went OTC and tried using it on a sore thumb joint, from excessive knitting and crocheting. I didn’t think it worked very well, and stopped when I realized why I was suddenly bruising much more easily. And that was just a little spot on one joint, nowhere near the recommended dosage.
The sublingual route can also be used for small-molecule meds that are rendered ineffective by stomach acid, like nitroglycerin or, for that matter, fentanyl. That’s how nicotine gum (and lollipops, which are compounded by some pharmacies) works.
p.s. Qadgop, I know you know that. Other Dopers may not.
This is my experience. I have a bunion that sometimes starts “pulsing” in pain when I lie in bed. (Other times too, but when I’m in bed, it keeps me from sleeping.) I put some Voltaren gel, and it stops hurting, letting me get to sleep. It very well could be a placebo effort, of course.
Another vote for Diclofenac. I had been using it quite a while to apply to Mrs. FtG’s back. I found that it was basically curing my Dupuytren’s Contracture. It’s almost completely gone away. (Searching, I don’t see any significant article in the Med community that has noticed this effect for Dupuytren’s.)
Mrs. FtG has a friend in Germany who is an immense fan of it. There it’s available OTC at a stronger dose.
This is me, too, and I use Aspercreme, which seems to tame the ache so I can sleep.
Just saw my orthopedist about a chronic problem. When I brought up diclofenac as a possible treatment, he very much favored it; said he’d used it in Europe, at twice the USA strength, and it worked very well for him.
It is very impressive how many people are in that 10% that have the medication work better than placebo …
Just the laying on of hands, even one’s own, can work wonders to reduce pain (short term).
I’m not in that group. (I just tried it again for the past couple of days, and realize reading this thread that i forgot, and stopped using it last night.) But if a placebo helps my pain, it worked. Who cares if it’s a placebo?
From the perspective of the user? The care should only be related to the cost if something is more likely helping by way of placebo effect. Cost in terms of possible adverse effect and money.
In this case the adverse effect risk is minimal and possibly positive if if reduces the chronic use of more systemic medications. And while these creams are not cheap they are not bank busting either.
So I also think these are great to use! Just maybe buy the generic?
This is why I’m doubtful that CBD balms work at all. I can rub anything on sore muscles and joints and they’ll feel somewhat better. I’m having some knee pain now, clearly not arthritis since my knees are artificial. Rubbing some CBD balm around the area helped a little for a little while but using menthol/alcohol stuff definitely eases the pain through the day, and it is diminishing now day be day. I’ve relied on alcohol as a treatment for muscle/tissue pain for nearly 50 years since a deep bruise on my thigh. A college athlete friend recommended adding a cup of isopropyl alcohol to a hot bath and soaking in it for 15 minutes. He also warned me not to repeat that often because I could poison myself. Later research shows that is unlikely but caution should still be used.
Applying that Voltaren 4x daily is becoming a PITA. Carrying the tube with me is a royal PITA. I doubt it will be helpful but I’ll do it regularly for awhile, 4x daily.
I made sure to read the label and the small print instructions. Possible liver damage with overuse? That got my attention.
I’m bumping this because there appears to be some benefit with Voltaren 4x daily. Right around the time I was saying, this is such a waste of time (and was also getting lazy at applying it), I began to ask myself, hey is the pain dissipating? I started feeling some relief. I will continue applying it, more religiously to see if there truly is pain relief.