Magnesium sulfate (medical use)


Magnesium sulfate as a medication is used to treat and prevent low blood magnesium and seizures in women with eclampsia. It is also used in the treatment of torsades de pointes, severe asthma exacerbations, constipation, and barium poisoning. It is given by injection into a vein or muscle as well as by mouth. As epsom salts, it is also used for mineral baths.
Common side effects include low blood pressure, skin flushing, and low blood calcium. Other side effects may include vomiting, muscle weakness, and decreased breathing. While there is evidence that use during pregnancy may harm the baby, the benefits in certain conditions are greater than the risks. Its use during breastfeeding is deemed to be safe. Magnesium sulfate for medical use is the magnesium sulfate heptahydrate salt. The way it works is not fully understood, but is believed to involve depressing the action of neurons.
Magnesium sulfate came into medical use at least as early as 1618. It is on the World Health Organization's List of Essential Medicines.

External uses

Bath salts

Magnesium sulfate is used in bath salts, especially for foot baths to soothe sore feet. The reason for the inclusion of the salt is partially cosmetic: the increase in ionic strength prevents some of the temporary skin wrinkling which would occur with plain water baths.
Epsom salt baths have been claimed to also soothe and hasten recovery of muscle pain, soreness, or injury. However, these claims have not been scientifically confirmed. The solubility of magnesium sulfate water is inhibited by lipids in lotions resulting in variable absorption rates when applied to the skin. Temperature and concentration are also factors.

Isolation tanks

Magnesium sulfate is commonly used in flotation therapy to prepare the concentrated solutions that fill the isolation tanks. Its high solubility in water yields baths with high specific gravity that making the body more buoyant. Its negligible toxicity is an important asset in that application.

Mineral waters

Magnesium and sulfate ions are naturally present in some mineral waters.

Drawing paste

In the UK, a medication containing magnesium sulfate, called "drawing paste", is claimed to be useful for small boils or localised infections, and removing splinters. The standard British Pharmacopoeia composition is dried magnesium sulfate 47.76%, phenol 0.49%, and glycerol to balance.

Internal uses

Magnesium sulfate can be administered internally by oral, respiratory, or intravenous routes.

Magnesium deficiency

Magnesium sulfate is used as a replacement therapy for magnesium deficiency

Arrhythmia

Magnesium sulfate may be used as an antiarrhythmic agent for torsades de pointes in cardiac arrest under the ECC guidelines and for managing quinidine-induced arrhythmias.

Asthma

Magnesium sulfate may be used as bronchodilator after beta-agonist and anticholinergic agents have been tried, e.g. in severe exacerbations of asthma, The salt can be administered by nebulization or by intravenous injection.

Eclampsia

Magnesium sulfate is effective in decreasing the risk that pre-eclampsia progresses to eclampsia. Intravenous magnesium sulfate is used to prevent and treat seizures of eclampsia. It reduces the systolic blood pressure but does not alter the diastolic blood pressure, so the blood perfusion to the fetus is not compromised. It is also commonly used for eclampsia where compared to diazepam or phenytoin it results in better outcomes.

Early delivery

Magnesium sulfate was once used as a tocolytic, but meta-analyses have failed to support it as an anti-contraction medication. Usage for prolonged periods may result in health problems for the baby.
In those at risk of an early delivery, magnesium sulfate appears to decrease the risk of cerebral palsy. It is unclear if it helps those who are born at term. Guidelines for the use of magnesium sulfate in mothers at risk of preterm labour are not strongly adhered to.

Research

Magnesium sulfate has been used as an experimental treatment of Irukandji syndrome caused by envenomation by certain species of Irukandji jellyfish, but the efficacy of this treatment remains unproven.

Safety

An abnormally elevated plasma concentration of magnesium is called hypermagnesemia.