I find the epsom is to be used internally, as a last resort. It works great as so many attest for the digestive flush but there are other options that are easier, unless of course one is in an acute condition and ive seen pain dissapear with these epsom flushes or as only choice resort when constipated. If you do a search on the questions about the magnesia, oxy and those types of commercial compounds I think you will come to the conclusion that tho they will cause noticable affect, most health conscious,herbal based practictiners see them as being unhealthily unballanced and not as good in a long term healing sense as compared to the more natural approaches like major diet change w herbal compounds assisting.
Tho the liver has a filtering function it isnt actually comprimized by how much naturally occuring chemically toxic fluid is passing thru it.It chemically changes what it can and the blood that isnt rectified stays moving, unless shunted, till it returns again. What taxxes and destroys the liver, apart from inorganic and directly antiorganic compounds, like alcohol, are the undigested food items that find their way into the bloodstream and other factors from over eating unhealthy fat , ect, and this is where the filtering aspect is affected negativly, causeing congested conditions and worse to this organ. I am a layperson so I may have wrong understanding about some of this but I do find that the use of thinking of the organs as filters, tho they do conventionally filter, to be counterproductive to our true understanding of their actions.
Addenda. This toxic circulating fluid in a toxified blood stream, is where I emphasize how our basic cellular structure becomes comprimized. Where before we notice organs being affected our cells become so pernmeated with high concentrations of unwanted exhaust items that they start to breakdown (acne) and become increasingly inefficient. I think this is where our genetic strutcture is first affected negativly also leading to the replication illness known as cancer.