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Magnesium sulfate (injection)

Generic name: magnesium sulfate (injection) [ mag-NEE-see-um-SUL-fate ]
Brand name: Magnesium Sulfate-Sodium Chloride injection
Dosage forms: injectable solution (50%), intravenous solution (1 g/100 mL-NaCl 0.9%; 1 g/50 mL-D5%; 1 g/50 mL-NaCl 0.9%; 10 mg/mL-D5%; 2 g/100 mL-D5%; 2 g/100 mL-NaCl 0.9%; 2 g/50 mL-D5%; 2 g/50 mL-NaCl 0.9%; 2 g/50 mL-sterile water; 20 g/500mL-sterile water; 3 g added to NaCl 0.9% 50 mL; 4 g/100 mL-NaCl 0.9%; 4 g/100 mL-sterile water; 4 g/50 mL-sterile water; 40 g/1000 mL-sterile water; 40 mg/mL-LR; 6 g/100 mL-D5%; 6 g/50 mL-D5%; 6 g/50 mL-NaCl 0.9%)
Drug classes: Laxatives, Minerals and electrolytes, Miscellaneous anticonvulsants

Medically reviewed by on Aug 16, 2023. Written by Cerner Multum.

What is magnesium sulfate injection?

Magnesium is a naturally occurring mineral that is important for many systems in the body especially the muscles and nerves.

Magnesium sulfate injection is used to treat hypomagnesemia (low levels of magnesium in your blood).

Magnesium sulfate injection is also used to prevent seizures in pregnant women with conditions such as pre-eclampsia, eclampsia, or toxemia of pregnancy.

Magnesium sulfate injection may also be used for purposes not listed in this medication guide.

Magnesium sulfate injection side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Tell your caregiver right away if you have:

  • feeling like you might pass out;

  • sweating, anxiety, cold feeling;

  • flushing (warmth, redness, or tingly feeling);

  • weak or shallow breathing;

  • extreme drowsiness, feeling very weak; or

  • numbness or tingly feeling around your mouth, muscle tightness or contraction, overactive reflexes.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


If possible before you receive magnesium sulfate, tell your doctor if you have kidney disease, heart disease, a stomach or intestinal disorder, or if you are dehydrated. Also tell your doctor if you drink alcohol or caffeine drinks regularly, if you smoke, or if you use any street drugs.

Before taking this medicine

Tell your doctor if you drink alcohol or caffeine drinks regularly, if you smoke, or if you use any street drugs. These factors can affect the way magnesium sulfate injection works in your body.

If possible before you receive magnesium sulfate, tell your doctor if you have:

  • kidney disease;

  • heart disease;

  • a stomach or intestinal disorder; or

  • if you are dehydrated.

You should not use magnesium sulfate if you are pregnant. It could harm the unborn baby. Use effective birth control, and tell your doctor if you become pregnant during treatment.

Magnesium sulfate can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby.

In an emergency situation it may not be possible to tell your caregivers if you are pregnant or breast feeding. Make sure any doctor caring for your pregnancy or your baby knows you have received this medication.

How is magnesium sulfate injection given?

Magnesium sulfate is injected into a muscle or into a vein through an IV. You will receive this injection in a clinic or hospital setting.

Your breathing, blood pressure, oxygen levels, and other vital signs will be watched closely while you are receiving magnesium sulfate.

What happens if I miss a dose?

Since magnesium sulfate is given by a healthcare professional, you are not likely to miss a dose.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while receiving magnesium sulfate injection?

Follow your doctor's instructions about any restrictions on food, beverages, or activity.

What other drugs will affect magnesium sulfate injection?

Tell your doctor about all medicines you use, and those you start or stop using during your treatment with magnesium sulfate, especially any IV (injected) antibiotics.

Other drugs may interact with magnesium sulfate, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.