Epsom Salt

Generic name: magnesium sulfate (epsom salt) [ mag-NEE-see-um-SUL-fate ]
Drug classes: Laxatives, Minerals and electrolytes, Miscellaneous anticonvulsants

Medically reviewed by Drugs.com on Mar 17, 2025. Written by Cerner Multum.

What is magnesium sulfate?

Magnesium is a naturally occurring mineral that is important for many systems in the body especially the muscles and nerves. Magnesium sulfate also increases water in the intestines.

Magnesium sulfate is used as a laxative to relieve occasional constipation.

Not all external uses for magnesium sulfate have been approved by the FDA. Epsom salt should not be used in place of medication prescribed for you by your doctor.

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

Magnesium sulfate side effects

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

Common side effects may include diarrhea or upset stomach.

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.

Related/similar drugs

Warnings

Never use a higher dose of magnesium sulfate than recommended on the package label, or as your doctor has directed. Using too much magnesium sulfate can cause serious, life-threatening side effects.

Do not use magnesium sulfate as a laxative without medical advice if you have: severe stomach pain, nausea, vomiting, a perforated bowel, a bowel obstruction, severe constipation, colitis, toxic megacolon, or a sudden change in bowel habits that has lasted 2 weeks or longer.

If you have rectal bleeding or if you do not have a bowel movement after using magnesium sulfate as a laxative, stop using the medication and call your doctor at once. These may be signs of a more serious condition.

Before taking this medicine

Do not use magnesium sulfate as a laxative without medical advice if you have:

• severe stomach pain;

• nausea or vomiting;

• a perforated bowel;

• a bowel obstruction or severe constipation;

• colitis or toxic megacolon; or

• a sudden change in bowel habits lasting 2 weeks or longer.

Ask a doctor or pharmacist if it is safe for you to take Epsom Salt if you have:

• diabetes;

• kidney disease;

• an eating disorder (anorexia or bulimia);

• if you have already been using a laxative for longer than 1 week; or

• if you on a low-magnesium diet.

It is not known whether magnesium sulfate will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication.

It is not known whether magnesium sulfate passes into breast milk or if it could harm a nursing baby. Tell your doctor if you are breast-feeding a baby.

How should I take magnesium sulfate?

Use exactly as directed on the label, or as prescribed by your doctor.

Never use a higher dose of magnesium sulfate than recommended on the package label, or as your doctor has directed. Using too much magnesium sulfate can cause serious, life-threatening side effects.

Magnesium sulfate may be used orally (by mouth) or as a soak. Follow your doctor's instructions or the directions on the package.

To take magnesium sulfate orally, dissolve one dose in 8 ounces of water. Stir this mixture and drink all of it right away. You may add a small amount of lemon juice to improve the taste of this mixture.

Magnesium sulfate taken orally should produce a bowel movement within 30 minutes to 6 hours.

Drink plenty of liquids while you are taking magnesium sulfate.

If you have rectal bleeding or if you do not have a bowel movement after using magnesium sulfate as a laxative, stop using the medication and call your doctor at once. These may be signs of a more serious condition.

To use magnesium sulfate as an epsom salt soak, dissolve in a large amount of water in a large bowl, a bucket, a foot tub, or a bath tub. Follow the directions on the product label about how much epsom salt to use per gallon of water.

Store at room temperature away from moisture and heat.

What happens if I miss a dose?

Since magnesium sulfate is used on an as needed basis, 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. An overdose of magnesium sulfate can be fatal

Overdose symptoms may include nausea, vomiting, flushing (warmth, redness, or tingly feeling), feeling very hot, slow heart rate, extreme drowsiness, or fainting.

What should I avoid while taking magnesium sulfate?

Magnesium sulfate taken orally can make it harder for your body to absorb other medications you take by mouth, especially antibiotics. Avoid taking other medicines within 2 hours before or after you take magnesium sulfate as a laxative.

What other drugs will affect magnesium sulfate?

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.

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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.

Medical Disclaimer

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