The following hypothesis was contributed by Derek H. Page and Hugh Smailes:

Several years ago, Ann Landers raised a provocative question in her column: does soap at the foot of the bed cure night-time leg cramps? The consensus in the medical community is no: there is no conceivable mechanism by which it could, so any relief derived from this procedure must be due to the placebo effect. In other words, it’s all in the mind.

But if it is indeed a placebo effect, it’s a remarkably strong one. Many people who have suffered for months, if not years, from painful, nocturnal cramps in their legs and feet have found immediate and long-lasting relief just by slipping a thin, innocent bar of soap beneath the sheets. Some even report relief although they were unaware that a bar of soap had been snuck into bed.

Likewise, others whose cramps have mysteriously returned have been nonplussed until they later discover that their bars of soap have fallen from the bed. From the point of view of those who, like us, are trying to solve this mystery, it is fortunate that several websites (including this one) have maintained reports of this unusual treatment and its results.

We decided that although these data were anecdotal, and therefore suspect, we would treat them as if they were scientifically valid, and use them to try to develop an explanation for soap’s seemingly helpful effects. But as soon as we started reading the literature, we realized what an enormous task we had undertaken. The anecdotal literature is vast, and frustratingly contradictory.

Nevertheless, we decided to continue, recognizing that any explanation we produced would remain an untested hypothesis. It would require testing by others before it could be elevated to the status of a theory. We decided to condense the relevant literature down to a few points on which there is general agreement. Here are the main relevant observations taken from the anecdotal evidence:

  1. It seems to work for many people. Soap in the bed appears to alleviate nocturnal leg cramps.
  2. Relief is immediate and sustained.
  3. Some people report that soap does not work. It appears either to work consistently and well or not at all. There are few cases of partial success.
  4. After a few months, a bar of soap is no longer effective for preventing cramps. It must be replaced. Old soap can be rejuvenated by scoring or shaving it to produce fresh surfaces.
  5. Some subjects have placed the soap between the sheets, and some have placed it under the bottom sheet. Either or both of these methods work.
  6. Some subjects report that direct physical contact between the subject and the soap is desirable, but few claim it is essential.

From these observations, certain conclusions may be drawn. For our purposes, number 4 on the above list is the most relevant. Apparently, the phenomenon can be switched off and on: off when the soap bar ages, and on again by scoring the soap. But why? What is it that’s being switched off and on? We hypothesize that it is an as-yet-unidentified molecule present in the soap. This might sound like a stretch, but in fact, this “switching” mechanism is consistent with what we know about the structure of soap.

Soap is a water-swollen gel. When it’s purchased, its moisture content is generally somewhere between 5 to 15 percent. Soap is very porous, and when it’s swollen with water, it permits small, dispersed molecules to pass through it. But when it has aged, its surface dries out, and its surface is a lot less porous, so small molecules can no longer pass through it.

We think that an unknown molecule that diffuses out of the soap gel is responsible for alleviating cramps. As long as the bar is emitting this molecule, the cramps are suppressed. An old bar of soap ceases to emit the molecule as the surface dries out and its resistance to diffusion rises. That’s when the cramps return. The bar can emit again–and once again eliminate cramps–after new, moister, fresher surfaces are exposed by scraping the bar of soap.

From items number 5 and 6 from our list above, we know that direct contact between soap and skin can be helpful, but it does not seem to be essential. This suggests that our unknown molecule is volatile, capable of diffusing in air: i.e., that it can pass from a bar of soap to your cramping leg in a manner similar to the way a drug is transmitted through a skin patch.

After generating this hypothesis, we took a careful look at the list of ingredients on a package of soap, and we found only one possible source of small molecules of a volatile compound: the fragrance. Nearly all soaps contain fragrances or perfumes. Certainly those mentioned in the anecdotal evidence do. And what perfumes are used in soaps? That’s generally top-secret information, held close to the vest by soap manufacturers. But we do know that most soaps contain esters and oils, such as carrot oil and lavender oil (or their synthetic doppelgangers). These compounds are vasodilators.Like the ester nitroglycerin, which is used to alleviate pain caused by angina, they enlarge blood vessels.

The quantity of perfume transmitted to the skin may be small, but it appears to be enough to dilate blood vessels and prevent cramps. We know, of course, that the small, mobile molecules in the fragrances of soap diffuse through its gel to the surface and evaporate. We know because we can smell them. And when you score an old bar of soap, you can smell it all over again, just as strongly as when you first took it from its paper wrapper.

Before it can be accepted, every new hypothesis has to be tested. We would welcome the findings of anyone who might want to test our hypothesis, and we would be eager to see the results. To the research community, which is convinced that ion imbalance is responsible for the initiation of cramps, we say that this suggestion doesn’t challenge that. There is ample room here for research by the academic and medical communities. Our proposed mechanism will surely be under attack within the week. Yet it fits much of the data so well that we suspect that whatever future research results are obtained the final conclusion in this matter will include much of what is written here.

Finally, it has not escaped our notice that if this explanation is correct, it may have applications beyond the alleviation of leg cramps–specifically, but not only, in the management of pain from other conditions. We hope that having proposed this scientifically viable explanation for the phenomenon of soap alleviating leg cramps will validate the experiences of those that have benefitted from this “treatment,” and open this area of inquiry to further medical and academic research. We do not claim originality for every element of this proposal. But we do claim originality for putting together the pieces of this puzzle.

To those who have been unable to get relief with the soap treatment (i.e., those mentioned in item 3 Above), we suggest you persevere and try a different soap with a stronger scent, potentially scoring it. You might try searching the internet, or this website, to see if there’s a brand others have had good luck with. The fresh, unwrapped bar of soap should then be placed between the sheets, preferably in a location where the soles of your feet can touch it. And please report back to us whether or not it works–we’d be very interested to hear.

 

Dr. Derek H. Page, (Baie D’Urfe, Quebec, Canada) and Hugh Smailes (Apollo Bay, Victoria, Australia) As a final disclaimer: we are not physicians and have no health expertise, as our critics will doubtless be happy to affirm.


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  1. Ann T.
    South Dakota
    Reply

    I get horrible toe and feet cramps mostly during the day but some at night. My toes take on a twisted (literally) life of their own. ‘Walking it off’ doesn’t help.

    I remembered the soap cure in the sheets at night. My toes and feet were cramping so badly in the early evening. I took calcium and no help.

    The spasms and cramps had gone on for hours. I grabbed two small bars of soap and put one in each sock that I was wearing. I stretched out on the couch and instant relief. Got up after awhile took out the soap-no more cramps. Ask me if I’m a believer!

  2. Mary
    Oregon
    Reply

    I have no idea why – but it DOES work. I was a lot more than skeptical after years of supplements and exersizes that do not work! I tried the soap and am amazed! A plain old bar of soap between the sheets and my legs have not cramped up since. I am sleeping so well now that I have soap where I really need it! What a trip.

  3. Patty
    USA
    Reply

    I don’t care if it is the placebo effect. Whatever, it works! But the reasoning was driving my husband and I crazy: So much so that we actually discussed it over dinner tonight.

    I had a nasty cramp in my left calf muscle (have no idea where it came from) for DAYS…..I even thought of going to my doctor about it. It was THAT painful. Then I remembered my bar of soap was there (I also have Restless legs – and it cured that). So, I put my left calf right on the bar of soap, next morning cramp was gone and hasn’t come back since.

  4. Patricia
    Limassol Cyprus
    Reply

    Just recently I developed cramps in my feet, going up my ankle, in the night. The third time it was truly excruciating. Looking on the internet, I saw many suggestions, but I chose the soap one for a good reason.
    First, on that night had I dreamed I was in a shop. The assistant was showing me soap, which I was refusing, as I use only organic vegetable soap with natural oils for aroma. When I read about using soap for cramps I bought the horrible branded stuff you find in the supermarket. It immediately stopped the cramp! I am no longer afraid. (Lifeboy and Dove). I put it in my socks as it was falling out of the bed.
    Why did I choose the soap cure? Decades ago in Scotland, after a pregnancy, a nasty marriage, living with awful inlaws, I got a bad kidney infection, and then a pus-filled thing on the end of my finger. Red and throbbing with pain. Nothing fixed it – hot kaolin poultices etc. My old grandad told me to grate green soap and mix it with sugar. Put this on as a poultice cold. Unbelievably it drew out all the poison!. Bravo soap!

  5. Susan B
    29455
    Reply

    I have been suffering from leg cramps for several years now, attributing them to my cholesterol medicine and dehydration. I was thrilled to be turned on to the soap remedy by a friend who heard about it from a friend. I tested it out and from the first night I found relief.

    I have not, in the past two months, had a full leg cramp or toe cramp in bed with the soap. I have however, gotten them while lying on top of the bed watching TV, but if I put my foot under the sheet and comforter, next to the soap it dissipates. I use Dial soap because my husband vetoed Irish Spring saying the scent was too strong. I think everyone with a cramping problem should try it.

  6. Carol Siegel
    Elkins park, pa
    Reply

    It absolutely works. I used to get extremely painful leg cramps during the night – almost every night. They would wake me up. The soap works! I put a bar in a sock between the sheets. The cramps all but stopped! If I feel one coming on, I simply rub the soap on the area and the cramping subsides. Amazing! Who would believe??!!

  7. Cindy
    United States
    Reply

    I have suffered with leg cramps at night that wake me out of a sound sleep and keep me up for awhile. Needless to say come morning I am really dragging. I had heard about the bar of soap awhile ago, but did nothing about it. I also read that the best soap was Ivory. I purchased 1 bar at the Dollar store, and it sat on my kitchen counter for about a month or so, (didn’t want to rush into anything)!

    This past Friday I had the worst leg cramp, I tend to get them in the front of my legs where there isn’t a lot of muscle to rub. I also exercise quite a bit, and take Spinning classes at least 3-4 times a week, so I figured it was from that. On Saturday night, same thing. Finally I had enough!

    I unwrapped the bar of Ivory and gently placed it at the foot of my bed between the fitted sheet and on top of the mattress pad. I have slept straight through the last 4 nights! And this includes last night after training with my Personal trainer who had me doing a lot of leg work and taking a Spin class! I will never go without a bar of soap under my sheet at the foot of the bed again!!!

  8. Old Rick
    Houston, Texas
    Reply

    My doctor laughs, my wife laughs, but it works. Irish spring seems to work best. We travel a lot and there must be a lot of room maids that wonder why soap is under the bottom sheet! I know this works because when it is not there here comes the “Charlie horses”. Just try it and see. I was very skeptical until I did and now I carry a bar of soap in my suitcase all the time!

  9. Tiza
    Reply

    I really don’t care if it’s a placebo or not. It works. But I don’t think it is because one lady’s husband wouldn’t use it. She was having foot or leg cramps, can’t remember, but he had bad charlie horses every night in his sleep. So one night she was still awake, and she could tell he was fixing to have a charlie horse because his leg tightened up and he moaned, so she crambed the soap under his leg. Instantly he fell back to sleep and never really woke up. The next morning, he didn’t know that he had a cramp like that, then his wife told him what she had done, which was the thing that he had made fun of.
    Needless to say, he started using it every night as well.

  10. l jo
    Reply

    I tried all kinds of over the counter drugs/vitamins and homeopathic remedies. By far this has worked the best. Why! Someone needs research this! it can’t be the placebo effect because I didn’t think it was going to work. I thought everyone was playing a prank on me.

  11. Meh
    Reply

    At night I don’t have cramping per se. Those usually happen in the late evening. Instead, I get a sensation of weakness accompanied by my left foot jerking or my left leg twitching. This keeps me up at night because the sensation is unpleasant. I’d heard about this through Dr. Gott’s newspaper column, but never thought to try it. Talking to a work colleague the subject of night cramping came up and I suggested this tool and searched the net to find some examples of people using it to send to her.
    That was yesterday.
    This morning, we compared notes. She started the usual toe and leg cramping and decided to use the soap – it worked, although she wants to use a less fragrant bar of soap.
    My left leg starts it’s dance, I put the soap under the sheet, it stop immediately, but the right leg (has never done this before) starting the twitching, so I kicked the soap between my feet and the right foot/leg quieted down and I was able to fall asleep.
    That bar of soap is staying under the covers!

  12. Shellly
    Reply

    Have posted comment a few minutes ago, as well as commented on several entries. As victim of MS, I again state the soap remedy is about the most effective cure of any drug, prescription or OTC, I’ve ever used for any ailment. Surprisingly, my MS doctor, head of the MS department for a large county in Florida, never heard of it, giggled to himself, jotted down a few words, but never acknowledged this amazing oddity.
    Perhaps the MS community, for whom muscle spasms are a way of life, should be educated through their physicians or the MS Society. I take prescription meds for high blood pressure and statins for cholesterol. Those numbers always vary, are definitely affected by climate and environmental changes, not to mention the continuous rise in price, and the inconvenience, though not great, of filling a script. Soap is always readily available, wherever you may be and whenever you may need it. I only wish there was such a simple solution to keeping BP and cholesterol numbers in check. Yuck, I hate swallowing pills!

  13. Shelly
    Reply

    The Hyland products seem to be a hit and miss remedy for me, whereas soap works all the time, all over, wherever a cramp or spasm used to strike. Less expensive too!

  14. Derek Page and Hugh Smailes
    Reply

    Thank you, Newell H, for the compliment. Much appreciated. It is probably easy as you say for an individual to do a simple experiment to test the hypothesis that vapor phase transfer is responsible for the beneficial effects of soap. However that would not convince anyone in the medical field.
    When we suggested a simple experiment (1) it was hoped that many interested sufferers of cramps would participate. A positive result from a number of subjects would perhaps persuade a university professor to do further work on the topic. Unfortunately not a single experiment has been reported. We hope the soap does work for you. If it does you are the perfect candidate for the experiment described in (1).
    Derek Page and Hugh Smailes
    1. Page, D.H. Peoplespharmacy.com January 2013

  15. Lizzy M.
    Reply

    I had heard about this from my mother a long time ago, and then again through a friend from work. Sometimes I get leg or toe cramps out of the blue late at night before I go to bed, and they can be “whoppers” very painful. Tonight I felt a thigh cramp coming on and grabbed a bar of soap someone had given us that is labeled “massaging soap.” I just put the dry soap right on my cramp, and within a few seconds it went away. Amazing! (By the way, it has a very nice fragrance).
    I found myself quite insulted when I read somebody’s answer to the soap “cure.” They said it was all in your head, a placebo effect, really, only working for those “gullible people” and why don’t they eat 4 bananas each day, and just lay still when it happens.
    Sounds like that person has never suffered from a leg cramp. If they had, they’d realize that people are not “gullible” but just desperate to find different things that might work. And just laying still when it happens doesn’t work for me at all. While it might be good to get more potassium in your diet (gatorade works pretty well, too), I’m pretty sure I’m not going to be eating 4 bananas each day.

  16. Carol E
    Reply

    Okay, soap was great for about six days. Then I was dying again, having to get out of bed and into the shower for relief. Then I went back online searching again, and I found Hyland’s Leg Cramp PM. Before I got any, though, my friend mentioned she uses some OTC stuff that works great. Turns out it was Hyland’s. It’s available at WalMart (but not all of them, apparently).
    So if the soap doesn’t work for you, I highly suggest Hyland’s!!
    Carol

  17. Newell H.
    Reply

    Me again: If it’s the fragrance then why not only perfume?
    Cheers again: NH

  18. Newell H.
    Reply

    Dr. Derek H. Page and Hugh Smailes: Your scientific enquiry and logic is superb and you deserve much credit on that score. Why not test it yourselves. It’s simple to do and then you get the professional credit for accomplishing that.
    I did my own research project 2 years ago and it had an application I never suspected. In 2 years it appears that no one is interested in its value but just this past year it has been referenced twice. You can find it at (it’s Open Source) DOI:10.4236/psych.2012.38093 if you’re interested. I remember a time when I was sitting around thinking, “I wonder how I’m ever going to accomplish that”, and I was 79 at the time.
    Anyway Dr. Page and Smaile, thanks for your excellent scientific sleuthing. IMO you 2 are excellent scientists. I’ve been looking all over for a cure for my leg cramps and I will certainly let you know if your cure works for me.
    Newell H.

  19. Anita
    Reply

    I have been using soap in my bed for about 5 years now, in fact the same bar. I don’t even remember the name. NO CRAMPS. When I feel one coming on I simply rub my foot over the bar and voila it’s gone. I just recommended this to a co-worker for her Mom. I printed this article because she gave me that “Yeah right” look.
    Try it. It really works.

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