Magnesium Sulfate: Side Effects, Uses, Dosage, Interactions, Warnings (2024)

• Uses
  • What Is Magnesium Sulfate Used For?
• Dosage
  • What Are Dosages of Magnesium Sulfate?
• Side Effects
  • What Are Side Effects Associated with Using Magnesium Sulfate?
• Drug Interactions
  • What Other Drugs Interact with Magnesium Sulfate?
• Warnings and Precautions
  • What Are Warnings and Precautions for Magnesium Sulfate?

What Is Magnesium Sulfate Used For?

Magnesium sulfate is a naturally occurring mineral used to control low blood levels of magnesium. Magnesium sulfate injection is also used for pediatric acute nephritis and to prevent seizures in severe pre-eclampsia, eclampsia, or toxemia of pregnancy.

Magnesium sulfate is available under the following different brand names: MgSO4.

What Are Dosages of Magnesium Sulfate?

Dosages of Magnesium Sulfate

Adult and Pediatric Dosage Forms and Strengths

Injectable solution

• 40 mg/mL
• 80 mg/mL

Infusion solution

• 1 g/100mL
• 2 g/100mL

Dosage Considerations – Should be Given as Follows:

Hypomagnesemia

Adult:

• Mild: 1 g intramuscularly (IM) every 6 hours for 4 doses
• Severe: 5 g intravenously (IV) over 3 hours
• Maintenance: 30-60 mg/kg/day IV

Pediatric

• Intravenous/intramuscular (IV/IM): 25-50 mg/kg every 4-6 hours for 3-4 doses as needed
• Oral: 100-200 mg/kg every 6 hours

Toxemia of Pregnancy

• Indicated to prevent seizures associated with pre-eclampsia, and for control of seizures with eclampsia
• 4-5 g (diluted in 250 mL NS/D5W) intravenously (IV) in combination with either (a) up to 10 g (10 mL of undiluted 50% solution) divided and administered intramuscularly (IM) into each buttock or (b) after initial IV dose, 1-3 g/ hour IV

Torsades de Pointes

• With pulse (ACLS): 1-2 g slow intravenous (IV) (diluted in 50-100 mL D5W) over 5-60 minutes, then 0.5-1 g/ hour IV
• Cardiac arrest (ACLS): 1-2 g slow IV (diluted in 10 mL D5W) over 5-20 minutes

Acute Nephritis, Pediatric

• 100 mg/kg intramuscularly (IM) every 4-6 hours as needed or 20-40 mg/kg IM as needed
• Severe: 100-200 mg/kg intravenously (IV) as 1-3% solution; administer total dose within 1 hour, one-half within first 15-20 minutes

Preterm Labor (Off-label)

• Used as a tocolytic to stop preterm labor
• Loading dose: 4-6 g intravenously (IV) over 20 minutes; maintenance: 2-4 g/hour IV for 12-24 hours as tolerated after contractions cease
• Do not exceed 5-7 days of continuous treatment; longer treatment duration may lead to low blood calcium (hypocalcemia) in developing fetuses resulting in neonates with skeletal abnormalities related to osteopenia

Bronchospasm, Pediatric (Off-label)

• 25-50 mg/kg intravenously (IV) over 10-20 minutes

Dosing Modifications

• Severe renal impairment: Do not exceed 20 g/48 hours

What Are Side Effects Associated with Using Magnesium Sulfate?

Side effects associated with the use of Magnesium Sulfate, include the following:

• Circulatory collapse
• Respiratory paralysis
• Low core body temperature (hypothermia)
• Excess fluid in the lungs (pulmonary edema)
• Depressed/poor reflexes
• Low blood pressure (hypotension)
• Flushing
• Drowsiness
• Depressed cardiac function/heart disturbances
• Increased sweating
• Low blood calcium (hypocalcemia)
• Low blood phosphates (hypophosphatemia)
• Low blood potassium (hyperkalemia)
• Visual changes
• Breathing difficulties
• Confusion
• Weakness
• Flushing (warmth, redness, or tingly feeling)
• Feeling like you might pass out
• Anxiety
• Cold feeling
• Extreme drowsiness
• Muscle tightness or contraction
• Headache

This document does not contain all possible common side effects and other side effects that may occur. Check with your physician for additional information about the side effects of this drug.

What Other Drugs Interact with Magnesium Sulfate?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

Magnesium sulfate has no known severe interactions with other drugs.

Serious interactions of magnesium sulfate include:

• demeclocycline
• doxycycline
• eltrombopag
• lymecycline
• minocycline
• oxytetracycline
• tetracycline

Magnesium sulfate has moderate interactions with at least 24 different drugs.

Magnesium sulfate has mild interactions with at least 43 different drugs.

This information does not contain all possible interactions or adverse effects. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns, or for more health information about this medicine.

What Are Warnings and Precautions for Magnesium Sulfate?

Warnings

• This medication contains magnesium sulfate. Do not take MgSO4 if you are allergic to magnesium sulfate or any ingredients contained in this drug.
• Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately

Contraindications

• Hypersensitivity
• Myocardial damage, diabetic coma, heart block
• Hypermagnesemia
• Hypercalcemia
• Administration during 2 hours preceding delivery for mothers with toxemia of pregnancy

Effects of Drug Abuse

• None

Short-Term Effects

• See "What Are Side Effects Associated with Using Magnesium Sulfate?"

Long-Term Effects

• Fetal skeletal demineralization, low blood calcium (hypocalcemia), and high blood magnesium (hypermagnesemia) abnormalities reported with continuous long-term use (i.e., longer than 5-7 days) for off-label treatment of preterm labor in pregnant women; the effect on the developing fetus may result in neonates with skeletal abnormalities.
• See "What Are Side Effects Associated with Using Magnesium Sulfate?”

Cautions

• Fetal skeletal demineralization, low blood calcium (hypocalcemia), and high blood magnesium (hypermagnesemia) abnormalities reported with continuous long-term use (i.e., longer than 5-7 days) for off-label treatment of preterm labor in pregnant women; the effect on the developing fetus may result in neonates with skeletal abnormalities.
• In patients with renal impairment, ensure that renal excretory capacity is not exceeded.
• Use with caution in digitalized patients.
• Use with extreme caution in patients with myasthenia gravis or other neuromuscular diseases.
• Low blood magnesium (hypomagnesemia) is usually associated with low blood potassium (hypokalemia) (potassium levels must be normalized).
• Monitor renal function, blood pressure, respiratory rate, and deep tendon reflex when magnesium sulfate is administered parenterally.

Pregnancy and Lactation

• Use magnesium sulfate during pregnancy only in LIFE-THREATENING emergencies when no safer drug is available. Positive evidence of human fetal risk.
• Fetal skeletal demineralization, low blood calcium (hypocalcemia), and high blood magnesium (hypermagnesemia) abnormalities reported with continuous long-term use (i.e., longer than 5-7 days) for off-label treatment of preterm labor in pregnant women; the effect on the developing fetus may result in neonates with skeletal abnormalities.
• Continuous administration of magnesium sulfate injection to treat preterm labor is not approved and that the safety and efficacy of use for this indication are not established.
• Magnesium sulfate is safe for use while breastfeeding.