your first mistake was using web md as an actual source of truth. the medical community is rife with liars and deceivers who only want you to take pharmaceuticals (you know, what the Bible refers to as SORCERY).
TIME TO WAKE UP
Find me *any* study of your choice showing uptake thru the skin of Epsom salts.
OK, how about this:
https://www.mdpi.com/2072-6643/9/8/813/htm
“In the following review, we evaluated the current literature and evidence-based data on transdermal magnesium application and show that the propagation of transdermal magnesium is scientifically unsupported.”
.