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Epsom salts: Full Drug Profile

Medically reviewed by Min Clinic Staff | Updated: January 2026

Epsom salts - General Information

A small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. (From AMA Drug Evaluations Annual, 1992, p1083)

 

Pharmacology of Epsom salts

Magnesium sulfate is a small colorless crystal used as an anticonvulsant, a cathartic, and an electrolyte replenisher in the treatment of pre-eclampsia and eclampsia. It causes direct inhibition of action potentials in myometrial muscle cells. Excitation and contraction are uncoupled, which decreases the frequency and force of contractions. Magnesium sulfate is gaining popularity as an initial treatment in the management of various dysrhythmias, particularly torsades de pointes, and dyrhythmias secondary to TCA overdose or digitalis toxicity.

 

Epsom salts for patients

Possible Adverse Effects

  1. ECG changes (prolongation of the atrio-ventricular conduction time, sinoatrial block and atrio-ventricular block).
  2. Circulatory collapse, hypotension.
  3. Gastro intestinal disturbances (diarrhoea, abdominal distension, absence of bowel sounds).
  4. Urinary retention.
  5. CNS depression (central sedation, muscle relaxation, hyporeflexia and decreased excitability).
  6. Calcium and potassium disturbances.
  7. Respiratory depression.

Special Considerations

  1. Anticipate change in calcium and phosphorus balance.
  2. Drug interaction has been reported between magnesium sulphate and gentamicin (respiratory arrest).
  3. Monitor serum magnesium and calcium levels.
  4. Antidote for hypermagnesaemia is calcium gluconate.

 

Epsom salts Interactions

 

Epsom salts Contraindications

Magnesium sulfate should not be administered parenterally in patients with heart block or myocardial damage.

 

Additional information about Epsom salts

Epsom salts Indication

Used for immediate control of life-threatening convulsions in the treatment of severe toxemias (pre-eclampsia and eclampsia) of pregnancy and in the treatment of acute nephritis in children. Also indicated for replacement therapy in magnesium deficiency, especially in acute hypomagnesemia accompanied by signs of tetany similar to those of hypocalcemia. Also used in uterine tetany as a myometriat relaxant.

Mechanism Of Action
Magnesium is the second most plentiful cation of the intracellular fluids. It is essential for the activity of many enzyme systems and plays an important role with regard to neurochemical transmission and muscular excitability. Magnesium sulfate reduces striated muscle contractions and blocks peripheral neuromuscular transmission by reducing acetylcholine release at the myoneural junction. Additionally, Magnesium inhibits Ca2+ influx through dihydropyridine-sensitive, voltage-dependent channels. This accounts for much of its relaxant action on vascular smooth muscle.
Generic Name
Magnesium Sulfate
Synonyms
Bitter salt; Magnesium sulfate anhydrous; Magnesium sulfate dried; Magnesium sulfate heptahydrate; Magnesium sulphate; Magnesium Sulphate Hydrate; Magnesium Sulphate Heptahydrate
Drug Category
Analgesics; Anesthetics; Anti-Arrhythmia Agents; Anticonvulsants; Calcium Channel Blockers; Tocolytic Agents
Drug Type
Small Molecule; Approved
Other Brand Names containing Magnesium Sulfate
Elliotts B Solution; Epsom salts; Hair salt; Kieserite [as monohydrate]; Sal amarum; Sal anglicum; Sal catharticum; Sal seidlitense; Salts of England; Sel d'angleterre;
Toxicity (Overdose)
LD50 = 1200 mg/kg (rat, subcutaneous). May be harmful if swallowed. May act as an irritant. Adverse reactions include hypotension, ECG changes, diarrhea, urinary retention, CNS depression and respiratory depression.
Protein Binding
25-30%
Biotransformation
None
Half Life
43.2 hours (for newborns)
Dosage Forms of Epsom salts
Solution Intravenous
Chemical IUPAC Name
magnesium sulfate
Chemical Formula
MgO4S
Organisms Affected
Humans and other mammals