Magnesium sulfate decomposes into magnesium oxide (MgO) and sulfur trioxide (SO). The heptahydrate can be prepared by neutralizing sulfuric acid with magnesium carbonate or oxide, but it is usually obtained directly from natural sources. It is on the WHO Model List of Essential Medicines, the most important medications needed in a basic health system. Magnesium sulfate is a common mineral pharmaceutical preparation of magnesium, commonly known as Epsom salt, used both externally and internally. Magnesium sulfate is highly water-soluble and solubility is inhibited with lipids typically used in lotions. Lotions often employ the use of emulsions or suspensions to include both oil
Magnesium hydroxide effects through the inclusion of aluminum hydroxide, which inhibits the contractions of smooth muscle cells in the gastrointestinal tract, thereby counterbalancing the contractions induced by the osmotic effects of the magnesium hydroxide. Magnesium hydroxide is also a component of antiperspirant. Magnesium hydroxide is useful against canker sores (aphthous ulcer) when used topically. Magnesium hydroxide powder is used industrially to neutralize acidic wastewaters. It also takes part in the Biorock method of building artificial reefs. Natural magnesium hydroxide (brucite) is used commercially as a fire retardant. Most industrially used magnesium hydroxide is produced synthetically. Like aluminium hydroxide, solid magnesium hydroxide has