Magnesium sulfate is MgSO4. In the natural state it is found in the hydrated state, with seven molecules of water of crystallization. In this form it is called as magnesium sulfate heptahydrate or Epsom salt and has the chemical formula MgSO4.7H2O. On heating up to 250°C, it loses all its molecules of water of crystallization and falls into a dry amorphous powder. Magnesium sulfate is a colorless and odorless powder, and is highly soluble in water.

Magnesium sulfate is an extremely versatile drug and has a variety of therapeutic uses. Magnesium sulfate taken orally can act as a laxative. When taken intravenously or intramuscularly, it can reduce the convulsions during labor and even halt premature labor. It can also be applied locally in the form of creams to treat inflammation of the skin and conditions such as ingrown nails.

Magnesium sulfate is used as a cure for a certain case of pregnancy-induced high blood pressure in women called preclampsia. It can also be administered when the condition of preclampsia aggravates and becomes the more chronic condition of eclampsia. Magnesium sulfate is administered intravenously to such patients. It can reduce the convulsions during eclampsia.

Excess dosage of magnesium sulfate can cause nausea, dizziness, severe constipation and vomiting along with muscle weakness and lethargy. It can also pass through the placenta and enter the bloodstream of the infant. However, magnesium sulfate is soluble in water and so its level within the body returns to normal within a few days.

Caution must be used when the person is already taking other drugs. Magnesium sulfate can react with ritodine and terbutaline and cause severe complications such as pulmonary edema and other cardiovascular problems. However, taken under the prescription of the physician, it is a mild to very effective drug for most of the problems mentioned above.

Besides therapeutic uses, magnesium sulfate also has some industrial uses. Due to its high affinity for water, it can be used as a dehydrating agent in organic syntheses. It also finds use as a bath salt in floatation therapy.