Epsom Salt vs Magnesium Supplements
Epsom salt baths versus magnesium supplements: what the sources say about absorption through skin, the swallowing risks of Epsom salt, and who should ask a clinician first.
Content last updated . This page has not been medically reviewed.
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Urgent warning: Epsom salt is not a harmless drink. Swallowing it as a laxative has caused severe, life-threatening magnesium poisoning, including a case that needed dialysis and developed altered mental status and respiratory depression. [1] If someone has swallowed Epsom salt and is weak, confused, has a slow heartbeat or trouble breathing, call 911. For other swallowing questions, call Poison Help at 1-800-222-1222.
These are not two versions of the same thing. Epsom salt is mostly magnesium sulfate, usually used in baths. [1] Magnesium supplements are taken by mouth, in several chemical forms. The claim that magnesium soaks through the skin better than a supplement is marketed widely, and a review we read calls the promotion of transdermal magnesium scientifically unsupported. [2]
What each one is and what the sources found
| Question | What the source found | Strength of evidence |
|---|---|---|
| Is skin absorption "better" than oral magnesium? | A review evaluated claims that magnesium sprays, flakes and salt baths work better than oral magnesium, and concluded the promotion of transdermal magnesium is scientifically unsupported. It notes oral supplementation for magnesium deficiency has been studied in detail. [2] | Marketing claim not supported by that review |
| Does any human study show absorption through skin? | A pilot study of 25 people used a magnesium cream (not a bath) or placebo cream for two weeks. Blood magnesium rose, but the change was statistically significant only in a subgroup of non-athletes, and the authors call for further study. [3] | Insufficient evidence: small pilot, cream, not Epsom salt |
| Are Epsom salt baths shown to fix low magnesium? | Proper evidence not found in the sources we read for a trial showing that Epsom salt baths correct low magnesium. We searched PubMed on 2026-10-23 for Epsom salt or magnesium sulfate baths against supplements and serum magnesium; results were animal, hospital or unrelated studies. | Not available |
| Is low magnesium common? | MedlinePlus says it is rare to be truly lacking in magnesium, although you may not get enough from your diet. [4] | Health-information statement |
| What goes wrong with too much? | MedlinePlus says side effects from high magnesium intake are not common except in people with significantly reduced kidney function, and that excess most often happens with too much in supplement form or with magnesium-containing laxatives. [4] | Health-information statement |
Epsom salt swallowed as a laxative
This is the main danger the sources describe. A case report describes a man who weakened, with a slow heartbeat and low blood pressure, after swallowing Epsom salt as a laxative; his magnesium level normalized after dialysis. [1] Another report describes a fatal case of high magnesium in a woman who regularly used magnesium-containing laxatives, and the authors say severe hypermagnesemia frequently results in death even with normal kidney function. [5] These are case reports, not rates, but they show the risk is real. See Epsom salt as a laxative: risks.
What a magnesium supplement does and does not settle
This page does not give an amount for any product; a clinician or pharmacist decides what is right for a person. Magnesium supplements have their own cautions, covered in magnesium and magnesium forms compared. People with kidney disease are the group the sources single out for high-magnesium side effects. [4]
Frequently asked questions
Is Epsom salt a magnesium supplement?
No. Epsom salt is mostly magnesium sulfate, and swallowing it has caused severe poisoning. [1]
Does magnesium absorb through the skin from a bath?
One review calls the promotion of transdermal magnesium scientifically unsupported, and a small cream pilot gave limited, mostly non-significant results. [2][3]
Can I drink Epsom salt for constipation?
Sources describe severe and fatal magnesium poisoning from swallowing Epsom salt or magnesium laxatives. Ask a pharmacist or clinician instead. [1][5]
Who is most at risk from too much magnesium?
MedlinePlus singles out people with significantly reduced kidney function. [4]
Am I probably low in magnesium?
MedlinePlus says true deficiency is rare, but a clinician can check whether a test or change is right for you. [4]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask first
Ask a clinician or pharmacist before swallowing any magnesium product if you have kidney disease, take regular medicines, are pregnant or breastfeeding, or are giving anything to a child. See kidney disease and supplements and how interactions work. Baths are covered separately in Epsom salt baths for muscle soreness and sleep and Epsom salt.
References
- Walker P, et al. Epsom Salt Ingestion Leading to Severe Hypermagnesemia Necessitating Dialysis. J Emerg Med. 2020. Read 2026-10-23.
- Gröber U, et al. Myth or Reality: Transdermal Magnesium?. Nutrients. 2017. Read 2026-10-23.
- Kass L, et al. Effect of transdermal magnesium cream on serum and urinary magnesium levels in humans: A pilot study. PLoS One. 2017. Read 2026-10-23.
- MedlinePlus. Magnesium in diet. National Library of Medicine. Read 2026-10-23.
- Bokhari SR, et al. Fatal Hypermagnesemia Due to Laxative Use. Am J Med Sci. 2018. Read 2026-10-23.