Washing soda reducing swelling? Old wives tale?

[Minkster]

Currently recovering from a broken ankle and whilst I was laid up in a cast I started reading various internet forums specifically for people in that situation. Of course, as with all this type of thing there are a fair amount of old wives tales or misinformation batting around but most can be batted away quite easily (such as the view that you should stop drinking caffeinated sodas because the phosphoric acid within them will slow down bone healing by up to 50% etc etc)

But theres a recent discussion about the merits of using washing soda crystals within a sock to reduce ankle swelling. The general view is that you place the crystals in the sock and place on swelling when you go to bed. Next morning the crystals have hardened as the fluid has been extracted from the swelling and hey presto the swelling has disappeared.

Obviously, swelling generally reduces overnight anyway whilst the ankle is elevated and crystals hardening doesn't in itself mean anything. Whilst the crystals may absorb fluid, I can't see how fluid under the skin can be extracted in this way, although I'm no doctor.

Looking online I expected to see a bunch of stuff on this with a skeptical view presented but I've searched and searched and found nothing.

So basically I'm asking, is this an accepted remedy for swelling?

[Modified]

Currently recovering from a broken ankle and whilst I was laid up in a cast I started reading various internet forums specifically for people in that situation. Of course, as with all this type of thing there are a fair amount of old wives tales or misinformation batting around but most can be batted away quite easily (such as the view that you should stop drinking caffeinated sodas because the phosphoric acid within them will slow down bone healing by up to 50% etc etc)

But theres a recent discussion about the merits of using washing soda crystals within a sock to reduce ankle swelling. The general view is that you place the crystals in the sock and place on swelling when you go to bed. Next morning the crystals have hardened as the fluid has been extracted from the swelling and hey presto the swelling has disappeared.

Obviously, swelling generally reduces overnight anyway whilst the ankle is elevated and crystals hardening doesn't in itself mean anything. Whilst the crystals may absorb fluid, I can't see how fluid under the skin can be extracted in this way, although I'm no doctor.

I would think that anything that could suck a significant amount of fluid from your flesh would severely damage your skin. It might reduce swelling caused by external irritation, like insect bites or burns, and perhaps that is the origin of the myth.

[strathmeyer]

What are "washing soda crystals"?

Are they harder to obtain than epsom salt?

[fuelair]

If the crystals are absorbing fluids (other than the water in sweat) you have another problem (how the fluid/water is moving to them) but if it is, they won't harden, they will start breaking down (dissolving).

[skeptigirl]

And now more than you ever wanted to know:

Swelling is all fluid dynamics: osmotic pressure, hydrostatic pressure, pulse pressure and some active cell intake or export of certain molecules across the cell membrane which affect osmotic pressure.

In lay language, with some technical stuff left out or we'd be here all day:

You injure the body part. Damaged cells release chemicals that dilate the arterioles which increases blood flow to the injured area. The increased blood flow allows greater hydrostatic and pulse pressure relative to uninjured parts of the body. The forces are then greater in the injured area and a greater amount of fluid is forced out of the capillaries into the inter-cellular space. You get swelling and the dilated capillaries make the site red and warm.

[snip: purpose & all the chemical neurotransmitters and other dynamics controlling all this]

When this is occurring (first 24 hours), after an injury (IE this is wrong approach for swelling in an infection), gentle to moderate pressure (don't cut off the blood flow), increases the inter-cellular pressure so less fluid enters, cooling constricts arterioles countering the blood vessel dilators, and elevation decreases intra-vein pressure which results in fluid moving into the veins from the far end of the capillaries since the pressure in the inter-cellular space is higher. This can limit swelling and bruising and can shorten healing time.

After 24 hours (longer for very severe injuries), the acute processes end and now the fluid dynamics revert to normal. You want to continue to use elevation and pressure to increase the return of the excess inter-cellular fluid to the bloodstream and decrease swelling by simple hydrostatic pressure. Heat increases blood flow but the mechanisms that allowed fluid to increase in the inter-cellular space are no longer at play so this time increased blood flow (as long as you don't have high hydrostatic pressure from the injured body part being too far below heart level) decreases the inter-cellular pressure as the osmotic pressure in the blood vessels which is pulling fluid into the vessels is continually renewed. As fluid moves into the blood stream from the inter-cellular space it normalizes osmotic and hydrostatic pressures. As you move the blood past the area, you carry the normalized pressures off and replace it with renewed negative pressure.


Some notes:
Hydrostatic pressure is simply the weight of the column of fluid.
Pulse pressure is the force of the fluid caused with each pulse wave generated by the heart.

Once through the capillaries, the pulse pressure is dissipated and you only have hydrostatic pressure. The blood is squeezed back to the heart by muscles contracting and the veins are full of one way valves so the squeezing of the veins pushes the blood in one direction.

The pumping action of your heart only affects the blood pressure on the arterial side of the blood stream. Pulse pressure dissipates over time/distance but is maintained up to the capillaries. Once through the capillaries, the vessels now get larger and pulse pressure doesn't go on.

If your venous pressure is high, it would be from blood backing up in the system. More goes in than goes out, the venous side gets fuller and the hydrostatic pressure rises. The end result is more fluid accumulating in the inter-cellular spaces including in the inter-cellular spaces in the lungs and you get pulmonary edema.

Osmotic pressure is the pressure of water molecules to flow toward equilibrium when certain other molecules are in solution. If you had no barrier, both water and the other molecules would move around until the molecules were evenly distributed. We call it diffusion but really both water and the diffusing molecules are moving. When you put a barrier that allows water to get through but not the other molecules, and you only have the molecules on one side of the barrier, the molecules create osmotic pressure and the water moves to the side with the molecules.


Which leads me to the point, (bet you thought I'd never get there. ;) )

All crystals, salts, etc that you put outside the skin cannot exert osmotic pressure on the fluid in the inter-cellular space. Sweat does not move via the pressures I described above. Sweat is actively transported into your pores and out of the body by the sweat glands.

If you were to tie this stuff around the injured ankle, chances are if it did anything, it increased hydrostatic pressure. You can wrap the ankle in a pressure wrap, skip the crystals.

And now I'm curious if/how epsom salts work and will have to go find out. They could have some effect on sweat glands or when in a 'bath' perhaps some osmosis can occur that wouldn't occur with dry skin. Or maybe they do little as well.

[ChristineR]

Washing soda is a key component in most powder laundry detergents and you can buy it in some supermarkets and hardware stores. Most name brand laundry products are a mixture of stuff, but people used to mix their own.

I do know that some astringent ointments and soaks placed on an open sore will reduce swelling and dry the wound out. Never heard of washing soda being used this way though.

[Pup]

I was always taught that washing soda was sodium carbonate, as opposed to sodium bicarbonate, baking soda.

[skeptigirl]

Only thing I can find on Epsom salt baths is treating psoriasis by removing scales and softening the skin or possibly decreasing the overacting immune response of the allergy component of psoriasis.

The salts may decrease itching.

Bottom line, the salts work on the skin but I see nothing that says they work on swelling or stimulating sweat glands to excrete excess fluid.

If anyone else knows I'd be interested. It's hard to find things sometimes when there are hundreds of woo sites to wade through to find the Internet sites with actual data.

[Cuddles]

Clothes are rinsed precisely to get rid of the washing soda. It can be very irritating and is generally not the sort of thing you want to have rubbed into your skin. There are plenty of perfectly safe things that absorb liquids that aren't irritating, such as salt and sugar. Of course, as Skeptigirl points out, putting something on your skin is very unlikely to do anything to the swelling at all, but even if it did, washing powder would not be the way to do it. Don't put washing powder on your skin.

[Minkster]

Thanks for the replies. It sounds like pressure may be reducing the swelling rather than the crystals, as people have suggested.

The person who mentioned this remedy referred to the soda as 'Lectric Soda' which is apparently a brand name in Australia

A quick google for 'Lectric Soda Swelling' seems to throw up a number of sites with the same claim

[JJM]

{snip} Bottom line, the salts work on the skin but I see nothing that says they work on swelling or stimulating sweat glands to excrete excess fluid.

If anyone else knows I'd be interested. It's hard to find things sometimes when there are hundreds of woo sites to wade through to find the Internet sites with actual data.I agree with everything you wrote; but you wrote it better than I could have. I used to be involved in formulating trans-dermal drugs, and it is not feasible to move significant quantities of water, in either direction, through healthy skin.

The use of salt for that purpose comes from the notion that the swollen area is a simple sack of fluid; I am surprised that using "washing salt" that way is not irritating. Worse than using salt- a friend of mine went to an acupuncturist who used the needle to make holes in her ankle, and then used suction cups to draw out blood.

[skeptigirl]

Boy that's dumb. All the cells damaged by the 'holes' and the excessive suction (like a hickey, cells have to break to get blood into the surrounding tissues) release more activators bringing the swelling cascade back online.