Muscle relaxants aren’t popular because they work well. “Spasm” is rarely what actually ails us, and muscle relaxants probably wouldn’t help much in any case. They are roughly equivalent to over-the-counter pain killers for acute back pain — the only condition for which there’s adequate evidence. Which obviously isn’t saying much. So why are they popular?
It’s probably because they’ve been around forever, because the drowsiness they cause makes them feel more potent than they actually are (relaxation and some psychoactive effects), and because relaxing muscles just seems like such a good idea to literally everyone, both patients and pros.
For these reasons, I think perhaps muscle relaxants have been grandfathered into modern, scientific medicine. They are tradition-based medicine, rather than evidence-based medicine.
This line of thought is a brief excerpt from a bunch of new information about muscle relaxants in both my frozen shoulder guide, and headaches guide — and the latter is still free for a few more days, so if you’d like to learn more, go there now.