Epsom Salt (Magnesium Sulfate) is a bronchodilator. It's good for inflammation/mucus in the lungs. There have even been medical tests which have shown it's effect on COPD and asthma. Quoting: Anonymous Coward 23794435
For more info, Google 'Magnesium Sulfate Lungs'.
Yes, with a caveat. It's given intravenously (IV). That means that someone at home couldn't do it. It might be that someone could figure out a way.
IV solutions directly enter the bloodstream. When a drug is usually given orally, it goes into the stomach, and then there are arteries around the stomach, and the drug passes across into these. Then the drug circulates and passes through the liver. Then over many treatments, the liver finally allows (first pass effect)the drug to pass more of more into the blood, for it restricts it until it overcomes the liver's ability to filter. They it reaches a therapeutic dose.
The kidneys do that too.
That means it would take a long long time to work orally, if at all.
Sublingual is a methodology that bypasses the first pass effect of the liver. It's under the tongue. It's possible one could try that to see if it produces a quick means of allieviating asthma by brochodialation.
When someone needs brochodialation, it is often an emergency and you need speed. As such, oral ingestion might not be quick enough to aid the patient's distress.
So unless you have an IV and a pure way to create a solution of the proper strength, then probably not.
Magnesium is a powerful regulator of the heart too, so you could, if in error of the correct percentages, stop or speed up the heart, which is dangerous.