Magnesium sulfate (By mouth, on the skin)

Magnesium Sulfate (mag-NEE-zee-um SUL-fate)

Treats constipation or used as a soaking solution for minor sprains, bruises, muscle aches, joint stiffness, and tired feet. This medicine is a laxative and soaking solution.

Brand Name(s):

Epsom Salt, First Aid Epsom Salt, Good Sense Epsom Salt, Quality Choice Epsom Salt, Sunmark Epsom Salt, Swan Epsom Salt

There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is generally considered safe for most people. Talk to your doctor if you have concerns.

How to Use This Medicine:

Ointment, Powder for Solution

  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • Follow the instructions on the medicine label if you are using this medicine without a prescription.
  • Laxative:
    • Dissolve the powder in 8 ounces (oz) of water.
    • Add lemon juice to the mixture to improve the taste.
  • Soaking solution:
    • Use this medicine only on your skin. Rinse it off right away if it gets on a cut or scrape. Do not get the medicine in your eyes, nose, or mouth.
    • Dissolve the powder in warm water for use as a compress, soaking solution, or bath.
    • As a compress, apply with a bandage or towel for 30 minutes up to 3 times per day.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light. If the powder has settled and formed a thick layer, gently tap the carton to free the granules.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

  • When used as a laxative, take the medicine at least 2 hours before or after other medicines.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, stomach pain, nausea, vomiting, diabetes, or a skin infection. Tell your doctor if you are on a magnesium-restricted diet, or if you noticed a sudden change in bowel habits that continued for more than 2 weeks or have already used a laxative for longer than a week.
  • Stop using this medicine and check with your doctor if you have:
    • Skin irritation or infection after using this medicine as a soaking aid.
    • Rectal bleeding or no bowel movement after using this medicine as a laxative.
  • Call your doctor if your symptoms do not improve or if they get worse.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Confusion, dizziness, irregular heartbeat, low blood pressure, muscle weakness, sleepiness
  • Skin irritation or infection after soaking

If you notice these less serious side effects, talk with your doctor:

  • Diarrhea

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 11/6/2020

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