Both Epsom salt and regular table salt share the common chemical classification of being a salt—an ionic compound formed from a reaction between an acid and a base. They are fundamentally distinct substances, however. The simple shared name often leads to the misconception that they are interchangeable forms of the same mineral. This core distinction is the key to understanding why one belongs in the kitchen and the other in the bath or garden.
The Core Chemical Distinction
The difference between these two compounds is clear at the atomic level, involving entirely different elements. Regular table salt is known chemically as sodium chloride, composed of the elements sodium and chlorine. These two elements bond together to form the familiar white, crystalline substance used globally for seasoning and food preservation. Conversely, Epsom salt is chemically known as magnesium sulfate, a compound made up of magnesium, sulfur, and oxygen.
While table salt is sodium-based, Epsom salt has no sodium content in its pure form. The presence of magnesium and sulfate ions in Epsom salt gives it a completely different set of chemical properties than the sodium and chloride ions in table salt. The name “salt” is purely a descriptor of its crystalline structure and ionic bond. The distinct elemental composition dictates how each substance behaves and is used.
Essential Differences in Practical Use
The unique chemical makeup of each substance leads to dramatically different applications in daily life. Table salt is almost exclusively used for culinary purposes, where its salty flavor is employed to season and enhance the taste of food. Its properties are also leveraged for food preservation, such as curing meats or pickling vegetables, by drawing out moisture through osmosis. Using table salt in a bath would simply result in salty water without therapeutic benefits.
Epsom salt is bitter and unpalatable, making it unsuitable for food flavoring. Its primary use is external and therapeutic, most famously by dissolving it in bathwater for muscle relief. The magnesium in the bath is thought to soothe aches, reduce soreness, and promote relaxation after physical exertion. Beyond bathing, it is also a popular supplement in horticulture, where it is used to correct magnesium or sulfur deficiencies in garden plants.
Safety and Consumption Considerations
It is important not to confuse these two salts, especially when it comes to consumption. Table salt is a dietary necessity, though it must be consumed in moderation as a source of sodium and chloride. Consuming Epsom salt as a seasoning or in large quantities is discouraged due to its powerful physiological effect.
Magnesium sulfate is an approved over-the-counter laxative that works by drawing water into the intestines to facilitate a bowel movement. Ingesting too much Epsom salt can lead to dehydration, severe diarrhea, and magnesium toxicity. Therefore, Epsom salt should never be used as a substitute for table salt in cooking, and any oral intake should strictly follow dosage instructions and preferably be done with medical consultation.