Magnesium Sulfate
Magnesium sulfate is the magnesium salt known as Epsom salt. As a medicine it is labeled as a saline laxative for occasional constipation.
What it is studied for
The strongest rated effects first. Bars show the size of the effect, the letter grades the evidence, and each rating lists the studies behind it.
What is Epsom salt?
Epsom salt is magnesium sulfate. The US medicinal product reviewed here contains magnesium sulfate heptahydrate and is labeled as a saline laxative for occasional constipation. That purpose differs from using magnesium to meet a nutritional requirement. 1
How does the laxative effect work?
Unabsorbed magnesium salts hold water in the intestine through an osmotic effect, helping explain their laxative action. The same effect can become unwanted diarrhea when magnesium is taken as a supplement. 2
Key studies
The most recent publications linked to Magnesium Sulfate's ratings.
Why people take it
SuppCo community snapshot, 2026-09-28. Reasons for use are not evidence that it works.
Questions people ask
Can an Epsom-salt bath correct a deficiency?
It has not been established as a reliable treatment. The transdermal review found insufficient evidence for dependable magnesium delivery through skin. 3
Is magnesium sulfate a daily wellness supplement?
The oral product reviewed here is labeled for occasional constipation. Its laxative directions should not be treated as a daily nutritional target. 1
How quickly does oral Epsom salt work?
The cited US label says a bowel movement generally occurs within half an hour to six hours. That timing applies to the medicinal oral product. 1
Can I recreate the mineral-water trial with bath salts?
The trial tested a specific natural mineral water. It provides no validated recipe or dosing equivalence for a homemade salt solution. 4
Magnesium Aspartate
Magnesium Glycinate
Magnesium Citrate
Magnesium Oxide
Magnesium Taurate
Magnesium Malate
Magnesium