Are magnesium and Epsom Salts the same thing?

November 15, 2025 •

2 min read

Despite their similar appearance, a 2024 article in National Geographic notes that scientific evidence suggesting significant absorption of magnesium through the skin from an Epsom salt bath is inconclusive. So, are magnesium and Epsom salts the same thing? No, and understanding the distinction is key for your health.

Quick Summary

Epsom salt is a magnesium sulfate compound, not the same as the elemental mineral magnesium. Their key differences involve chemical composition, absorption by the body, and primary uses, which are vital distinctions for consumer choices.

Key Points

Not the Same: Epsom salt is a chemical compound (magnesium sulfate), whereas magnesium is an essential elemental mineral.
Limited Absorption via Baths: The transdermal absorption of magnesium from an Epsom salt bath is minimal and not a reliable way to fix a deficiency.
Magnesium Chloride Flakes are Better: For transdermal supplementation, magnesium chloride flakes offer superior absorption and bioavailability compared to Epsom salt.
Oral Supplements for Deficiencies: The most effective method for increasing systemic magnesium levels is through oral supplements, such as magnesium citrate or glycinate.
Cautions for Oral Use: Ingesting Epsom salt is a common laxative use, but it can cause severe side effects in high doses and should only be done with medical guidance.
Warm Water is a Key Factor: The perceived relaxation benefits of an Epsom salt bath are largely due to the effects of the warm water itself, which improves blood flow and soothes muscles.

The Core Difference: Compound vs. Mineral

Magnesium is a natural element essential for over 300 biochemical reactions in the human body, found in foods and supplements. Epsom salt is a specific compound, magnesium sulfate (MgSO₄), containing magnesium, sulfur, and oxygen. Therefore, Epsom salt contains magnesium but is not pure magnesium.

What is Elemental Magnesium?

Magnesium ($Mg$) is a vital mineral in the human body, critical for many processes. In supplements, it's bound to other substances, forming compounds like magnesium citrate or glycinate, affecting absorption and effects.

What is Epsom Salt (Magnesium Sulfate)?

Epsom salt is hydrated magnesium sulfate, named after Epsom, England. It dissolves into magnesium and sulfate ions in water. Traditionally used in baths for muscle soothing and stress reduction, sulfates may also aid detoxification.

Absorption and Bioavailability: Are Baths Enough?

While Epsom salt baths are popular for muscle relaxation and stress reduction, scientific evidence for significant magnesium absorption through the skin is limited. The benefits may be largely due to the warm water itself. Magnesium chloride (flakes/oil) is considered more effectively absorbed transdermally. Oral supplements like magnesium citrate and malate are typically the most bioavailable for systemic increase.

Comparing Magnesium Forms and Their Uses

Common Applications:

Epsom Salt (Magnesium Sulfate): Primarily used in baths; can be an oral laxative under caution.
Magnesium Flakes (Magnesium Chloride): Used in baths and topical applications for better skin absorption and magnesium replenishment.
Magnesium Supplements (e.g., Citrate, Glycinate): Taken orally for deficiency, sleep, nerve/muscle function, and blood pressure.


Comparison of Epsom Salt and Magnesium Flakes	Feature	Epsom Salt (Magnesium Sulfate)	Magnesium Flakes (Magnesium Chloride)
Composition	Magnesium, Sulfur, and Oxygen (MgSO₄)	Magnesium and Chlorine (MgCl₂)
Absorption (Transdermal)	Lower bioavailability; rapidly excreted by the kidneys	Higher bioavailability; more readily absorbed and retained
Primary Use (Bath)	Soothing sore muscles, stress relief, relaxation	Replenishing magnesium levels, muscle relaxation, improved skin health
Cost	Generally more affordable and widely available	Often more expensive due to sourcing from ancient seabeds
Best For	General relaxation, short-term muscle soreness	Targeted magnesium supplementation via the skin, long-lasting effects

Potential Side Effects and Precautions

External use of Epsom salt baths is generally safe. However, oral intake of excessive magnesium from supplements or laxatives can cause overdose (hypermagnesemia) with symptoms like nausea, diarrhea, and muscle weakness, and in severe cases, be fatal. Oral use requires careful dosing and medical oversight, especially for those with kidney or heart conditions.

Conclusion: Choosing the Right Magnesium Source for You

Magnesium and Epsom salts are not the same; magnesium is an essential mineral, and Epsom salt is magnesium sulfate. While Epsom salt baths offer relaxation benefits, largely from the warm water, they are not an effective way to significantly increase systemic magnesium levels. Magnesium chloride flakes provide better transdermal absorption, and oral supplements are most reliable for addressing deficiencies. Choose based on your goals, like relaxation or targeted supplementation. Always consult a healthcare provider about magnesium deficiency or before starting supplements. For more information, visit the National Institutes of Health website.

Frequently Asked Questions

No, studies suggest that the amount of magnesium absorbed through the skin from an Epsom salt bath is minimal and not sufficient to correct a magnesium deficiency. The relaxing effects are often from the warm bathwater itself.

Magnesium chloride is another type of magnesium salt, often sold as flakes for bathing. It has a higher bioavailability and is more readily absorbed through the skin than magnesium sulfate (Epsom salt), making it more effective for transdermal magnesium intake.

Epsom salt is a potent laxative and should only be ingested as directed by a healthcare professional or package instructions. Overconsumption can lead to severe side effects like diarrhea, dehydration, and in rare cases, magnesium toxicity.

Both can offer relief through a warm bath. However, due to its higher absorption rate through the skin, magnesium chloride flakes may be more effective for replenishing magnesium levels and providing muscle relaxation.

Yes, oral magnesium supplements come in various forms, including magnesium citrate, glycinate, malate, and oxide. Forms like citrate and glycinate are generally considered to have higher bioavailability than oxide.

Excessive intake of magnesium, especially from oral supplements or laxatives, can lead to side effects like diarrhea, nausea, abdominal cramps, and in serious cases, dangerous drops in blood pressure and heart function problems.

The most reliable way to increase systemic magnesium levels is through a diet rich in magnesium-containing foods (nuts, seeds, leafy greens) or by taking high-bioavailability oral supplements. A healthcare provider can recommend the best approach for you.