SaveYourself.ca helps you solve pain problems

published 10/26/06, updated 6/28/10

Do Epsom Salts Work?

There is (still) no good reason to believe that Epsom salt baths aid recovery from muscle pain, soreness or injury

by Paul Ingraham, Vancouver, Canada MORE
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Credentials and qualifications

I am a writer and retired Registered Massage Therapist (unusually well-trained for a massage therapist, a 3000-hour program). I’m almost done with a Bachelor of Health Sciences degree. I am a peer reviewer for The Natural Standard, and a copyeditor for Science-Based Medicine. My most important qualification is more than a decade of workaholic post-graduate study, clinical experience, and constant conversations with readers from around the world, including many experts who have provided countless suggestions and criticisms.

For more information, see: Who Am I to Say? More information about my qualifications, credentials and professional experiences for my readers and customers.


Welcome to what is — oddly — the most popular article on the internet about Epsom salts. In the last year, this page has become the dominant source of information about Epsom salts online. Apparently, I have written more about this subject than anyone else ever has! Many, many people who Google for Epsom salts end up right here. Incredibly, this means that I get some hate mail about Epsom salts. I’m not joking. Some people, apparently, feel very strongly about their baths. So, about Epsom salts …

The whole article in one paragraph

Epsom salt in your bath is cheap and harmless and it makes bath water feel “silkier,” so there’s no reason to ban it from your life. However, it probably doesn’t do what you hope it’s doing. Although Epsom salt probably does have some physiological effects, it is unknown if there is a therapeutic effect on aches and pains … and somewhat unlikely. Most of the theories you hear are oversimplified and meaningless, and the known effects of Epsom salt don’t have much to do with muscle pain. The belief that it helps could easily be due just to the heat of the bath. The case for the healing powers of Epsom salt is mostly made by people selling the stuff, or recommending it as casually and imprecisely as an old wives’ tale.

Epsom salts are magnesium sulfate heptahydrate, usually shortened just to magnesium sulfate. It was originally obtained by boiling down mineral waters at Epsom, England. It is quaintly referred to in the plural — Epsom salts instead of Epsom salt — but it’s just one kind of salt, and other than tradition there’s no more reason to say “salts” than there is to say “please pass the table salts.”

The chemical structure of Epsom salts … so that you know this is a <em>serious</em> article.

The chemical structure of Epsom salts … so that you know this is a serious article.


Supposedly good for pain in your muscles

A cup or two of Epsom salt in a bath supposedly relieves pain — specifically, muscle pain from over-exertion (delayed-onset muscle soreness), conditions like myofascial pain syndrome (trigger points, or muscle knots) and fibromyalgia — and speeds healing from minor injuries such as sprains and tendonitis. Note that “relieves pain” and “speeds healing” are as different as a flying dream and actually flying.

Claims and recommendations of this nature are widely published, and can be found by the thousands with a quick Google search. Bags and cartons of Epsom salts are available at any drugstore, with instructions for use in baths. I have a package right here that says:

Dissolve desired amount (1–2 cups) of crystals in a hot bath to produce a mineral water treatment to aid in the relief of muscular aches and pains.

When I went to school, my instructors suggested Epsom salt baths as a good thing to prescribe to our clients. No scientific basis for this idea was ever presented: it was just one of those things that everybody “knew,” a folk remedy justified by the generations of wise old wives and bathers. The physiology of it certainly wasn’t made clear to us. Occasionally someone made a vague reference to “detoxifying” the muscles, perhaps “by osmosis.” Nothing more exact was ever discussed because, frankly, I am sure that not one person in the building could have even named the molecule “magnesium sulfate.”1

No evidence for the efficacy of Epsom salts was ever presented, nor did it seem necessary to talk about it.

Ever since then, I have wondered if there was anything to it. I am strongly skeptical of all health-related claims involving “toxins,” mostly because people who toss that word around almost never actually know which specific toxins they are talking about.2 I have thoroughly studied the subject of post-exercise muscle soreness — which is probably the leading cause of hot baths — only to discover that it’s basically been proven that there are no known remedies for it.3 And after a long, hot Epsom salt bath of my own one night — which had no apparent effect on my unusually sore muscles — I decided it was time for a reality check.

Does an Epsom salt bath do anything?

A word from my sponsor … which is, um, me …

This educational website offers more than 400 free articles about pain problems, but it is also partially funded by the sale of e-books for people with pain problems. If you are researching Epsom salts because you have frustrating muscle pain, please also read the free introduction to this book, which is by far the most advanced self-help guide on this topic published anywhere:

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Myofascial trigger points — muscle knots — are increasingly recognized by all health professionals as the cause of most of the world’s aches and pains. This detailed tutorial focuses on advanced troubleshooting for patients who have failed to get relief from basic tactics, but it’s also ideal for starting beginners on the right foot, and for pros who need to stay current. 213 sections grounded in the famous texts of Drs. Travell & Simons, as well as more recent science, this constantly updated tutorial is also offered as a free bonus (2-for-1) with the low back, neck, muscle, or iliotibial pain tutorials. Add it to your shopping cart now ($19.95) or read the first few sections for free!

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A crystal of magnesium sulfate heptahydrate — Epsom salt.

A crystal of magnesium sulfate heptahydrate — Epsom salt.

Almost no Epsom salt science

My search for scientific evidence concerning Epsom salt baths was disappointing. I was unable to find even a single scientific paper studying their effect on body pain.4 Folk remedies are often generally neglected by researchers, but not usually so completely. There are usually at least a few experiments testing popular remedies kicking around. Why wouldn’t the use of Epsom salts for muscle soreness be similarly blessed?

There is plenty of research relevant to other medical uses of Epsom salts.5 For instance, on my package of Epsom salts, instructions are also given for internal usage as a laxative — which does work67 and is actually FDA approved and probably the most common and generally known medical usage. Other uses of magnesium sulfate include the treatment of irregular heart rhythm, low blood magnesium,8 eclampsia,9 and severe tetanus.10

But there appears to be simply nothing at all published about alleviating aches and pains or “detoxification.” Apparently, researchers just aren’t interested, or (more likely) they simply can’t get funding for the work.

It seems like researchers just aren’t interested in studying the effect of Epsom salts on muscle pain.

Strangely, Epsom salt baths do not even rate a mention in Home Remedies: Hydrotherapy, massage, charcoal, and other simple treatments, a large and credibly referenced compendium of traditional remedies assembled by a pair of doctors. They describe five medicated baths — alkaline (soda) baths, starch baths, oatmeal baths, peroxide baths, and sulfur baths — for conditions ranging from poison ivy rashes to diabetic gangrene (!), but they never mention Epsom salt baths. Could they possibly have just neglected it? Or is it more likely that Epsom salt baths simply have no (clear, known) medical usage?

In the perfect absence of any testing, all we can do is speculate about the possible mechanisms of action. Is there any plausible way that Epsom salts could have an effect on your muscle tissue, or on the healing of injuries?

“Detoxification” and “osmosis” explain nothing about Epsom salts

Regardless of whether Epsom salts baths work, it’s important to understand that the words “detoxification” and “osmosis” are virtually the only explanations offered — and they are both hopelessly misleading. Usage of these terms mostly just reveals a poor understanding of both toxins and osmosis. If we are to understand Epsom salt, we need to get past this and understand it for the right reasons.

The osmosis/detoxification explanation is never actually clarified in any detail by the people tossing the words around. Presumably it is intended to mean — roughly — that either osmosis is actually a mechanism of detoxification (getting something nasty out of the body through the skin), or that osmosis is the mechanism by which something in Epsom salts can get into the body and then have a detoxifying effect.

People often mistakenly believe that osmosis refers to the movement of substances — ions and molecules — across a membrane. Alas, that is simply wrong by definition. Osmosis does not move particles. Osmosis refers to the movement of water only across thin membranes, towards higher concentrations of dissolved substances.11

Osmosis and all the wee beasties

Reader Dorrie B. pointed out something interesting: Epsom salts might be an effective treatment for topical skin infections, as salt is certainly inhospitable to microganisms. Osmosis may not be able to transport salt ions across the skin, but it certainly isn’t kind to bacteria in this equation: it sucks them dry.

But this is also a great example of how complex these questions can be, because salt bathing might also damage populations of other bacteria on the skin, resulting in higher vulnerability to infection.12 Do people who bathe or swim in salt water regularly suffer any ill effects? Are they more susceptible to new infections? They might well be: a 10% difference would not be obvious even to the victims, but would nevertheless be clinically significant and biologically interesting.

Likely that research hasn’t been done, but my point is just that it’s really surprisingly difficult to say whether or not a given biological effect is “good” — it’s almost never that simple, and it’s a good thing to bear in mind throughout this article.

You can demonstrate this clearly by soaking a potato in salty water: the water is “sucked” osmotically out of the cells, they lose their plumpness, and the potato goes limp. Poor little potato. It’s the water that moves around.

Skin is waterproof (though not Epsom salt proof)

So, however Epsom salts get into the body — and they probably do, more about this below — it’s not by osmosis. Osmosis doesn’t work through the skin. Skin is almost completely waterproof. If it weren’t, you would dehydrate like an earthworm on a sunny sidewalk.

The top layer of the skin, the stratum corneum, consists of dead cells stuffed with a kind of embalming substance, keratin, a fibrous protein. They are mostly impermeable to water, and additionally we have glands that coat the skin in waterproofing oils. When those oils wash off, the dead skin cells can soak up water and swell, like soaked beans. Since the top layer of the skin is attached to the layers below, which do not swell, the top layer wrinkles or “prunes.”13

That swelling of the superficial skin cells is not due to osmosis, but rather to a limited “capillary action” in which water molecules flow into small spaces. (Paper towels absorb liquid the same way.) The stratum corneum is mostly waterproof precisely because osmosis is not a significant factor here. Those cells are dead. They contain mostly just dry keratin — not fluid containing dissolved substances which could osmotically “suck” water into them.

Furthermore, the stratum corneum is generally an effective barrier to diffusion: ions and molecules dissolved in water cannot generally pass through the stratum corneum, again because there is virtually no water in the outer layers of skin for them to diffuse through. This is not to say that nothing gets past the skin, just not much. It is lipid (fat) permeable, which is why solvents are quite dangerous to us, and why we can get rashes from toxic oils from plants, and how we can easily get a medicine through it (as in nicotine or hormone patches). But a great deal else is kept out — and that's a good thing, too! The skin is a vital defensive layer, a physical barrier that prevents infection and dehydration.

Rosemary Waring finds strong evidence that magnesium sulfate does indeed get past the skin

When I originally wrote this article in 2005 or so, there was no evidence that Epsom salts could even get past the skin, nor any likely mechanism for it. In 2006, Rosemary Waring, a British biochemist at the University of Birmingham, changed all that.

Dr. Waring did a nice science experiment with Epsom salts.14 She did more or less exactly what any curious person would do if she wanted to know whether or not Epsom salts can get past skin: she measured magnesium and sulfate in the blood and urine both before and after people bathed in Epsom salts.

Dr. Rosemary<br>Waring

Dr. Rosemary
Waring

She found them to be higher after the baths! 16 out of 19 people had more magnesium and sulfate in their blood after the baths than they did before the baths.15 Fascinating!

Dr. Waring’s results are straightforward. No therapeutic effects of Epsom salt were studied or claimed — she just studied absorption, and did not try to make any more of it, showing the restraint of a pro. What could be simpler?

I was so interested in these results (although still a bit skeptical) that I contacted Dr. Waring by email. “I agree that it is a bit surprising,” she replied, “but the results are certainly there and in fact there are hints in the past literature that this could happen.”

Better still, Dr. Waring told me that a colleague of hers in London has done another experiment which showed that “magnesium sulphate can cross human skin using pieces of excised human skin in a special apparatus.”

Now four years later, neither experiment has yet actually been published,16 and that’s a reason for caution. It is a basic rule of science that evidence can’t really be taken too seriously until it has been exposed to peer review and repeated by other scientists. Just because experimental results haven’t been replicated yet doesn’t mean we ignore them, but it does mean that we have to take them with a grain of salt. (That pun was simply unavoidable — so sorry.)

Meanwhile, what can we make of Dr. Waring’s results? One thing only so far …

  1. There probably is a mechanism for getting magnesium and sulfate across the skin!

It’s not much, but it’s important. And when I found the new evidence, I changed my mind. (That’s how science works. That’s why being anti-science is like being anti-honesty.17 I happily admit that Dr. Waring’s results probably mean that I was simply dead wrong about the absorption question originally. I was so actually so pleased to be wrong that I wrote an article summarizing this situation and talking a little about what a pleasure it is to be wrong about something in science.)

Up your bum? Um …

When you encounter surprising results in science, don’t just settle on the first explanation that comes to mind — it could easily be wrong. Dr. Waring says that she “assumed that it simply diffuses across the stratum corneum,” and that certainly is possible. But what other explanation could there be for the results? How else could magnesium sulfate have gotten into the bloodstream in her experiment? Reader Adrian J. had an unusual idea (which just screamed “funny sidebar!”):

Is it possible that the salt diffuses across the epithelium in the anus if the rectum relaxes to some degree in the warm water?

Wow, that’s some awesome lateral thinking! And I think it’s plausible. But I find myself (uncomfortably) wondering ... just how much do I relax in a hot bath? That much? And how much salt could diffuse across that more permeable but much smaller membrane? It’s a small target! And I shudder to think of the measures required to test this hypothesis …

And you thought an article about salt baths would be boring!

How does it work, this crossing of the skin? Dr. Waring: “I don’t have any evidence as to how magnesium sulfate crosses the skin, though I have always assumed that it simply diffuses across the stratum corneum, helped by the fact that it’s in a hot bath.” Molecules certainly do diffuse much more quickly in heat. I’m still not clear myself on how ions diffuse through the fairly arid and water-proof stratum corneum, but it does seem that they are getting through it somehow. There may also be an active transport mechanism — that is, skin cells may actually spend energy to drag salt molecules into the body.

(But it still ain’t osmosis, and that’s still well worth emphasizing.)

What do magnesium and sulfate ions do once they cross the skin?

If Epsom salts do get across the skin … so what? Is it any good to have a few extra ions of magnesium and sulfate kicking around your bloodstream? The rest of this article continues to mostly cast doubt on the possible therapeutic effects.

There might well be a therapeutic effect, but we have no information about what it is, how it works, what it works for, how strong the effects are, and so on. The increased levels of these ions shown by Dr. Waring’s experiment are small, about a 10% increase on average (and none in some subjects, remember). The concentrations could also be quite different in the fluids between cells — she didn’t measure that. It is still completely unclear what effects these ions could have on your tissues when they arrive.

There is no doubt that magnesium sulfate has effects on physiology. Several of those effects are reasonably well known, including a few common medical applications mentioned earlier. There are also unpleasant effects. But, judging from the established medical uses of Epsom salt, there is definitely no particular reason so far to believe that having more magnesium or sulfate in your blood is going to be much use to you — unless you have eclampsia or tetanus or autism.18

The closest thing there is to a relevant science experiment is one study of injected magnesium sulfate which found that it “did not reduce muscle pain” and caused “unpleasant side effects.”19 Yuck! Not exactly encouraging!

So there’s not really any particular reason to believe anything about the therapeutic effects of Epsom salts for aches and pain. We can really only speculate.

No matter what it can do, it can’t do everything

This is a classic problem with all kinds of supposedly amazing pain cures: pain has too many different causes for one medicine to be really effective.

There are many types of muscle and joint pain that have little or nothing at all in common with each other physiologically. For instance, the pain of fibromyalgia originates in dysfunction of the central nervous system, which is completely different from the pain caused by exercise, which in turn is completely different than the physiology of trigger points. Even “basic” muscle pain is incredibly complex and has many flavours.20

While it’s certainly conceivable that increasing levels of magnesium and/or sulfate ions in the bloodstream could help with some pain problems, it’s extremely unlikely that it would help enough different kinds of pain to be generally “good for” pain” This is a really important logical point! Nothing can be a magic bullet that will help all types of pain, or even more than a couple of them.

Similarly, Epsom salts probably cannot simultaneous perform the two tricks most often touted: “relieve pain” and “speed healing.” Those are completely different things.

They might even be mutually exclusive. For instance, the primary source of injury pain is inflammation — a complex and painful physiological process intended to … wait for it … speed healing. Indeed, the only known mechanism by which you could recover faster from an injury would be to increase inflammation. If bathing in Epsom salts did that, it would make you hurt more, not less. Of course, there could be other ways to speed up healing — in an “anything’s possible” kind of way — but it’s still pretty far-fetched that a single molecule could pull off both that miracle and reduce pain at the same time.

The point here is just that the conventional wisdom is pretty murky.

What’s a calcium channel, how do Epsom salts block it, and who cares?

Generally speaking, explanations for the benefits of Epsom salts are really vague, as discussed above: “osmosis and detoxification.” Once in a blue moon, you’ll see Epsom salts (or magnesium in particular) more exactingly described as a “calcium channel blocker” with the implication that this is obviously “good for pain.”

Unsurprisingly, this is another misleading oversimplification. Although it’s more specific and impressive sounding, it’s not a heck of a lot more meaningful than “detoxification.”

Calcium channels are itsy bitsy — molecular scale21 — holes in cell walls that let calcium in and out as a trigger for a bunch of biochemical business. They exist primarily in muscle tissue (including the heart), blood vessels, and neurons. There are a number of druggy ways to interfere with them, including magnesium. Calcium channel blockage is a reasonably well understood bit of physiology, and the main clinical usage of calcium channel blockers is to decrease blood pressure by reducing the strength of muscle contraction in the heart and blood vessels. Although other effects undoubtedly exist, there is no particular reason to believe that they have any potent effect on any flavour of pain.

Lots of people are walking around with calcium blockers in their blood. Calcium blockers aren’t rare drugs. Since there are numerous drugs that block calcium channels in various ways, it’s a bit implausible that there would be some kind of powerful pain-killing effect that no one’s noticed. I don’t think, as a rule, that people on calcium channel blockers are walking around feeling no pain, like a superpower.

Yes, it is possible that magnesium absorbed through the skin does something different, something good, for certain kinds of pain. After all, different calcium blocker drugs have different effects! But there’s not a shred of good, direct evidence of it. So it really boggles the mind that anyone would toss this idea around with any confidence. Seriously, they’re pretty much making it up as they go — wild speculation.

I don’t think that people on calcium channel blockers are walking around feeling no pain.

Magnesium as a pain-killer after surgery

There is some limited evidence that magnesium (just that ion) may reduce pain, perhaps because it is a “calcium channel blocker and N-methyl-D-aspartate antagonist,” as in a 2009 experiment.22 However, this is uncertain science. Several studies have been done, with conflicting results. Most were reviewed in 2007:23 four showed a positive effect, seven showed no effect greater than a placebo, and in one experiment the subjects actually experienced more pain (ouch).

Naturally, the authors of the review concluded: “These trials do not provide convincing evidence that perioperative magnesium may have favorable effects on postoperative pain intensity and analgesic requirements.” So much for the miracle of calcium channel blockage: it fails the “impress me” test.

Clearly, this mystery is not solved yet. There is a plausible mechanism for reducing pain, but it is clearly neither well understood nor reliable.

Do you suppose the picture is any clearer for Epsom salts in your bath? Don’t bet on it!

Sulfate supplementation

I asked Dr. Waring to speculate about the therapeutic effects. She pointed out that patients with rheumatoid arthritis are known to have low sulfate levels. Molecules produced by the inflamed tissues in these patients may interfere with the production of a protein that is used to produce sulfate from another molecule (cysteine), thus lowering sulfate levels.24

However, low sulfate levels are a possible result of having rheumatoid arthritis, not a cause — and thus boosting them back up again will not necessarily solve anything. And even if it did, that’s a therapeutic effect that is very particular to rheumatoid arthritis — a serious, agonizing joint disease — which probably has little or nothing to do with the kinds of pain that most people put Epsom salt in their baths for.

It would be great if Epsom salt baths helped people with rheumatoid arthritis, but good evidence of that would, in a way, pretty much shoot down the other claims of therapeutic effect, which rely on completely different ideas about how and why Epsom salt might work. But, of course, there is as yet no evidence one way or the other.

Consider the source!

Dr. Waring’s results are irrelevant to the popular idea of “osmosis,” which refers to the movement of water, not molecules. Nor do her results imply anything about that other popular concept associated with Epsom salts, “detoxification.” And yet, 99% of the time, “osmosis” and “detoxification” are the concepts presented as the justification for bathing in Epsom salts. Can you trust advice that simplistic?

The detoxification claim implies either that Epsom salts somehow “suck” toxic substances out of your muscle tissues, or that Epsom salts get into your system and then somehow “clean up” some toxic substances that they encounter. There is no scientific evidence at all for either of those basic detoxification scenarios, and both involve some seriously optimistic assumptions, leaps of logic, avoidance of detail … all made by people who are usually trying to sell the stuff.

Epsom salt bath prescriptions are invariably brief, and are often accompanied by really strange claims of healing powers. For instance, I found one website that recommended taking Epsom salts internally as well as bathing in them:

Researchers in nutrition, through controlled experimentation, have found that Magnesium Sulfate accelerates the body’s healing time by 30%. As an example, if an injury required three weeks to heal under normal or standard conditions, it would only require two weeks to heal if Magnesium Sulfate was added to the diet as a nutrition [sic].25

That’s really ludicrous. Accelerated healing time is a comic book concept — something Wolverine does — not an even remotely legitimate medical concept. And imagine the unpleasant surprise of the hapless reader who takes this advice when they discover the laxative effects of ingesting Epsom salts! Naturally, no source for this alleged experiment was given.

Epsom salts bathing is often recommended carelessly and overconfidently, without any genuine knowledge of the physiology or science (or lack thereof). Those who claim to “know” that Epsom salts work cannot seem to demontrate that they also “know” much about physiology or science. While it certainly remains possible that there is a therapeutic effect, it’s pretty clear that we shouldn’t take their word for it.

Nice-feeling water and floatation therapy

Is there any other reason to put Epsom salts in your bath? Well, Epsom salts dissolved in your bath does make the water feel nice. No research is required to prove that: just try it! Most people agree that the water feels smoother, slicker, silkier.

And it makes you floatier! But only ever so slightly. High concentrations of Epsom salt in your bath will increase the water’s specific gravity (density) to the point where you will start to float — just like in the Dead Sea, or Utah’s Great Salt Lake — because the body is, on average, much less dense than salty water. The concentrations of salt required for floatation therapy are much higher than Epsom salt packaging recommends, by the way.26 However, any salt in your bath — Epsom or otherwise — is going to make you at least a little bit lighter in the water.

Most people agree that Epsom salts make water feel “smoother.”

The purpose of floatation therapy is primarily to reap the benefits of deep relaxation, which are noteworthy.27 It sounds lovely to me — but irrelevant to the relief of muscle aches and pains except via the straightforward (and perfectly legit) mechanism of relaxation.

Something like a conclusion about Epsom salts

I can do no better in defense of Epsom salt bathing for aches and pains than “anything is possible.” There is no good or particular reason to believe that bathing in dissolved Epsom salts will have the slightest effect on muscle soreness or injury recovery time. Although this folk wisdom may someday prove to have a sound rationale, clearly there is none that its advocates have thought of — or even tried to think of, it seems.

On the bright side, thanks to Dr. Waring, we now know that we are a living experiment in absorbing magnesium sulfate ions every time we bathe in dissolved Epsom salts! And maybe they do something. And it’s very cheap, and almost certainly safe — just as no one is obviously getting any miracle cures out of Epsom salt bathing, they aren’t suffering any obvious ill effects either.

So, why not? At the very least, they’ll make your bath feel silkier! And at most? Who knows — maybe those magnesium and sulfate ions do have some healing powers. It’s certainly not impossible. Just don’t buy into all the crap about osmosis and detoxification. As the old Scottish proverb says, “Always keep your mind open — but not so open that your brains fall out!”

Still need help with myofascial pain?

If you think this article is detailed, you should see my tutorial about muscle pain and myofascial pain syndrome! This kind of exhaustively researched writing about Epsom salts is only possible because I sell some of the other articles on this website. No writer can afford to create truly good, detailed content and then just give it all away: we have to make a living somehow. Please reward my efforts by taking a look at my tutorials. Although Epsom salts seem unlikely to be a significant source of relief, there are plenty of other options for self-treatment of muscle pain. SaveYourself.ca publishes an extremely thorough tutorial about myofascial trigger points (muscle knots):

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ADVANCED TUTORIAL

Save Yourself from Trigger Points & Myofascial Pain Syndrome!

Myofascial trigger points — muscle knots — are increasingly recognized by all health professionals as the cause of most of the world’s aches and pains. This detailed tutorial focuses on advanced troubleshooting for patients who have failed to get relief from basic tactics, but it’s also ideal for starting beginners on the right foot, and for pros who need to stay current. 213 sections grounded in the famous texts of Drs. Travell & Simons, as well as more recent science, this constantly updated tutorial is also offered as a free bonus (2-for-1) with the low back, neck, muscle, or iliotibial pain tutorials. Add it to your shopping cart now ($19.95) or read the first few sections for free!

  $1995


Further Reading

Other interesting reading:

What’s New In this Article?

Monday, June 28, 2010 — Added information about the effect of Epsom salt on bacteria on the kin.

Monday, March 22, 2010 — Corrected several typographic errors.

Previous updates unlogged.

Notes

  1. I still can’t remember it reliably, because chemical names stick in my head about as well as my cousins’ birthdays. Ambush me with the question sometime: “What’s the chemical name for Epsom salts? Schnell, schnell!” I’ll be stumped as likely as not. Return to text.
  2. The idea of “toxins” is usually used as a tactic to scare people into buying snake oil of one sort or another. It’s not that there’s no such thing as a toxin — obviously there are toxic substances in the environment. The problem is the kind of people who toss the idea around, and the reasons they do it (profit), and the inevitable lack of any specific claim or scientific evidence to support it. “Detoxification” may be the single most common marketing buzzword in alternative health care, and yet exactly which toxins we’re talking about, or exactly how they are disposed of, is never explained by anyone selling a product that supposedly detoxifies — because they don’t know. For more information, see “Detoxification” Schemes and Scams (from QuackWatch.org). Return to text.
  3. For more detail, see another article on SaveYourself.ca, You Can’t Beat DOMS! The myth of treatment for nature’s little tax on exercise, delayed onset muscle soreness (DOMS). Return to text.
  4. My standard search sources are PubMed and The Cochrane Collaboration. Return to text.
  5. Swain et al. Southern Medical Journal. 1999. See also the Wikipedia article magnesium sulfate (Wikipedia). Return to text.
  6. Izzo et al. Magnes Res. 1996. “A common use for high doses of oral magnesium salts is to produce a laxative effect to treat constipation,” explain the authors of this scientific paper. “In the intestinal lumen the poorly absorbable magnesium ions (and other ions such as sulphate) exert an osmotic effect and cause water to be retained in the intestinal lumen.” Return to text.
  7. James et al. Pediatrics. 1995. This paper compared the effectiveness of different laxatives, showing that Epsom salts do indeed move the bowels along … but not as quickly as sorbitol. Return to text.
  8. As occurs with chronic diarrhea, magnesium malabsorption, alcoholism, diuretic use and a few other disorders. Return to text.
  9. Eclampsia is a dangerous and fairly common complication of pregnancy. Return to text.
  10. Muscle spasms caused by bacterial infection with Clostridium tetani, which produces the neurotoxin tetanospasmin. Return to text.
  11. I’m deliberately over-simplifying the definition of osmosis there, just for readability. Osmosis actually involves the movement of any solvent across a membrane. And water is a solvent, of course. I referred only to water in this context because, unless you bathe in turpentine, the only solvent in your bathing-osmosis equation is going to be good ol’ H2O. Return to text.
  12. It is now well understood that every microscopic nook and cranny of our skin — indeed, our entire body, inside and out — is thickly populated with an ecosystem of microorganisms, more diverse than any jungle (see We Are Full of Critters). It is also likely that one of the primary functions of these teensy jungles is to maintain a balance of power, where it’s difficult for any organism to dominate. If soaking in salt water kills bacteria, it might kill off the bacteria that normally live on the skin as well. Return to text.
  13. Why do fingers and toes wrinkle in the bathtub? www.LOC.gov. 2009. A good quality short article from the Library of Congress “Everyday Mysteries” series about the phenomenon of skin wrinkling or “pruning” in water. Return to text.
  14. Waring. Report on Absorption of magnesium sulfate (Epsom salts) across the skin. Unpublished. 2006. Return to text.
  15. The others had increased urine levels of magnesium, implying that “the magnesium ions had crossed the skin barrier and had been excreted via the kidney, presumably because the blood levels were already optimal.” In other words, whatever magnesium was absorbed into the bloodstream was promptly removed by the body. Return to text.
  16. When I asked Dr. Waring about publication, she explained “we just haven’t got around to it yet. I hope to do a bit more and then publish with my London colleague.” So both experiments mentioned here probably will be published in due time. As of July 2009, they still have not been to the best of my knowledge. Return to text.
  17. Little rant there. It really gets my knickers in a twist when people gripe about science “not knowing everything,” or “there’s other ways of knowing.” As if science doesn’t know it has limits! If scientists thought everything was done, they would stop! Sheesh. Return to text.
  18. Dr. Waring has done other research showing that autism is correlated with magnesium deficiency, and her primary reason for studying Epsom salt absorption through the skin was to investigate it as a possible autism treatment Return to text.
  19. Chestnutt et al. “Failure of magnesium sulphate to prevent suxamethonium induced muscle pains.” Anaesthesia. 1985. Full Abstract:
    In fit unpremedicated patients undergoing minor operations and who were ambulant on the afternoon of the operations, pretreatment with magnesium sulphate given intravenously did not reduce the incidence of suxamethonium induced myalgia below that in a similar series who received no prophylactic therapy. The injection of magnesium in conscious patients is followed by unpleasant side effects.
    Return to text.
  20. Consider the seminal text, Muscle Pain: Understanding Its Nature, Diagnosis and Treatment. It has nine chapters devoted to nine different kinds of muscle pain. It also doesn’t mention Epsom salts. Not once. Return to text.
  21. Cell Size and Scale. learn.genetics.utah.edu. 2010. A beautiful animated tool for visualizing the scale of cells. Return to text.
  22. Kogler. Acta Clin Croat. 2009. Return to text.
  23. Lysakowski et al. Anesth Analg. 2007. Return to text.
  24. Dr. Waring: “The cytokines released in the inflammatory state actually depress the expression of cysteine dioxygenase, the rate-determining step in the conversion of cysteine to inorganic sulfate. About 80% of the in vivo requirement of sulfate goes through this pathway as sulfate is not well-absorbed from the gut.” Return to text.
  25. Epsom Salt & Apple Cider Vinegar Treatments Nature's Healing & High Energy Bath. RacingSmarter.com. 2006. Return to text.
  26. Which actually suggests an interesting point: if modest amounts of Epsom salts in your bath allegedly has therapeutic effects, then it is reasonable to guess that the much higher concentrations of salt used in floatation therapy or found in the famous salt lakes would have a really dramatic effect — perhaps even a toxic effect. But bathing in much higher concentrations of salt has no significant effect at all … other than making people float. Return to text.
  27. A UK floatation tank manufacturer’s website, floataway.com, admirably restrains itself from extravagant claims of medical benefits, discussing only the benefits of relaxation. As for Epsom salt, the website says it is used “because it raises the density of the water, making it easy to float, and because it has a silky feel which is very good for the skin.” I’m not sure what they mean by “good for,” but I’m guessing it just feels pleasant. Return to text.