How does epsom salt work?

I have this thing, a bloated out balloon that resembles a foot. Last night, Edlyn insisted that I submerge it in a bat of epsom salt. I was skeptical, but sure enough, it helped a lot. The swelling subsided considerably, and I could put some weight on it.

How does that work?

Well, epsom salt is primarily magnesium sulfate, so I started looking at the effects of that compound on swelling. I haven’t come up with anything definitive enough to cite, but here are some of the general ideas I’ve gotten (no doubt one of our resident docs will be along to correct me soon):

Some of the magnesium can be absorbed through the skin; this may affect local calcium regulation and thereby influence the transfer of water across the cell membrane. Essentially, it increases the saturation of intercellular fluid relative to intracellular fluid, causing water to migrate out of the cells and into the bloodstream. This may account for the references I’m seen to the salt bath improving circulation in exposed extremities.

Then, too, the salt baths generally involve warm water, which may increase circulation on its own.

If I find out more, I’ll post it.

Thanks for replying, Balance.

The water was lukewarm at most. I’d say room temp. In fact, I remarked to Edlyn how “cold” it was and that I’d thought it was supposed to be hot. So, it couldn’t be warmth that did anything.

I’m struggling, though, to understand your descriptions of the cellular effects. Are you saying that the fluid that causes the swelling is water that escaped from cells but can’t get back in? And the epsom salt helps the cells “drink” up the fluid?

Check out SDMB Thread : How Do Epsom Salts Work ?

http://boards.straightdope.com/sdmb/showthread.php?threadid=54367