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Magnesium sulfate heptahydrate

For relief of occasional constipation (irregularity). This product generally produces bowel movement in ½ to 6 hours.

Checked against the official label · Updated

Sold without prescription in some countries Oral Safety alerts on record

Magnesium sulfate heptahydrate: quick answers

Used for
For relief of occasional constipation (irregularity).
Usual adult dose
Adults and children 12 years of age and over 10 (3/4 tbsp.) to 30 grams (2 ½ tbsps.).
Children
Children 6 to under 12 years of age 5 (½ tbsp.) to 10 grams (3/4 tbsp.).
Prescription
Sold without prescription in the United States; rules differ by country.

From the official label (Jul 2025). Your prescription and pharmacist come first.

How to use Magnesium sulfate heptahydrate

What the official label says. If a doctor prescribed it, follow the prescription. Your pack's leaflet comes first if it is different.

Who it is for

For relief of occasional constipation (irregularity). This product generally produces bowel movement in ½ to 6 hours.

How to take it and how often
  • Tbsp = tablespoon drink a full glass (8 ounces) of liquid with each dose
  • The dose may be taken as a single daily dose or in divided doses
  • Do not exceed maximum daily dosage, unless directed by a doctor
  • Adults and children 12 years of age and over 10 (3/4 tbsp.) to 30 grams (2 ½ tbsps.)
  • Children 6 to under 12 years of age 5 (½ tbsp.) to 10 grams (3/4 tbsp.)
  • Children under 6 years of age consult a doctor
Talk to a doctor first if

abdominal pain, nausea, or vomiting are present noticed a sudden change in bowel habits that persists over a period of 2 weeks kidney disease a magnesium-restricted diet

Warnings

Do not use laxative products for more than 1 week unless directed Ask a doctor before use if you have abdominal pain, nausea, or vomiting are present noticed a sudden change in bowel habits that persists over a period of 2 weeks kidney disease a magnesium-restricted diet Stop use and ask a doctor if rectal bleeding occurs you fail to have a bowel movement after use of a laxative. This may indicate a serious condition. If pregnant or breast-feeding ask a health professional before use. Keep this and all drugs out of reach of children. In case of overdose, get medical help or contact a Poison Control Center right away.

Possible side effects

Rectal bleeding occurs you fail to have a bowel movement after use of a laxative. This may indicate a serious condition.

Pregnancy and breastfeeding

If pregnant or breast-feeding ask a health professional before use.

How to store it

Keep out of reach of children.

If you miss a dose

Take it when you remember, unless it is nearly time for the next dose. Then skip the missed one. Never take two doses at once to make up for it. Check your leaflet, as some medicines are different.

From the official U.S. FDA label for this active ingredient. Your pack may have a different strength, so always read its leaflet. If a doctor prescribed it, follow the prescription. Ask a pharmacist if you are unsure. Label dated 2025-07-28.

Brands around the world

Products with Magnesium sulfate heptahydrate as the active ingredient. Names differ between countries.

Registered products

United States (FDA)

Magnesium SulfateMAGNESIUM SULFATE HEPTAHYDRATE 500 mg/mL · Injection, Solution · REMEDYREPACK INC.
NDC 70518-4375Label
Magnesia SulphuricaMAGNESIUM SULFATE HEPTAHYDRATE 30 [hp_C]/30[hp_C] · Pellet · Boiron
NDC 0220-3267Label
Magnesium SulfateMAGNESIUM SULFATE HEPTAHYDRATE 500 mg/mL · Injection, Solution · Medical Purchasing Solutions, LLC
NDC 71872-7229Label
Magnesium SulfateMAGNESIUM SULFATE HEPTAHYDRATE 40 mg/mL · Injection, Solution · Fresenius Kabi USA, LLC
NDC 63323-106Label
Magnesium SulfateMAGNESIUM SULFATE HEPTAHYDRATE 40 mg/mL · Injection, Solution · Fresenius Kabi USA, LLC
NDC 63323-106Label

Other countries: check your pack's registration number and we point you to your regulator.

Safety alerts and recalls

EPSOM SALT(Magnesium Sulfate Heptahydrate, USP), 50 lb multi-wall bag, Rx only, Manufactured by PQ Corporation, P.O. Box 840, Valley Forge, Pennsylvania USA 19482.U.S. FDA Class III
29 Oct 2015 · PQ Corporation · TerminatedFailed Impurities/Degradation Specifications: Level of iron exceeds the limit set by the USP monograph for it (USP limit is NMT 0.5 ug/g (ppm)).

A recall usually affects certain batches only. Compare the lot number on your pack.

Check your pack of Magnesium sulfate heptahydrate

Type the registration number on the pack, or scan it with your camera.

Or take photos of the pack
3 free checks left today Official sources: U.S. FDA · EMA (EU) · Health Canada · WHO alerts

Questions about Magnesium sulfate heptahydrate

What is Magnesium sulfate heptahydrate used for?

For relief of occasional constipation (irregularity). This product generally produces bowel movement in ½ to 6 hours. (From the official U.S. FDA label.)

How do I take Magnesium sulfate heptahydrate?

Follow your prescription or the leaflet in your pack. The official label says: tbsp = tablespoon drink a full glass (8 ounces) of liquid with each dose. The dose may be taken as a single daily dose or in divided doses. do not exceed maximum daily dosage, unless directed by a doctor adults and children 12 years of age and over 10 (3/4 tbsp.) to 30 grams (2 ½ tbsps.) children 6 to under 12 years of age 5 (½ tbsp.) to 10 grams (3/4 tbsp.) children under 6 ye…

Can I take Magnesium sulfate heptahydrate while breastfeeding?

If pregnant or breast-feeding ask a health professional before use. Ask your doctor or midwife first.

Do I need a prescription for Magnesium sulfate heptahydrate?

In many countries Magnesium sulfate heptahydrate is sold without a prescription in some strengths. Rules differ by country, so ask a pharmacist.

What brands contain Magnesium sulfate heptahydrate?

Magnesium sulfate heptahydrate is sold under names such as Rapidol Sal Inglesa. Brand names differ between countries.

What are the side effects of Magnesium sulfate heptahydrate?

The official label lists: rectal bleeding occurs you fail to have a bowel movement after use of a laxative. This may indicate a serious condition. Tell your doctor about any side effect that bothers you or does not go away.

Can children take Magnesium sulfate heptahydrate?

The label gives a separate dose by age: children 12 years. Check the pack or ask a pharmacist.

Can I take Magnesium sulfate heptahydrate when pregnant or breastfeeding?

If pregnant or breast-feeding ask a health professional before use. Ask your doctor or midwife first.

How can I check that my Magnesium sulfate heptahydrate is genuine?

Scan the registration number on your pack with PillVera (NAFDAC number in Nigeria, NDC in the United States, DIN in Canada), check the expiry date and buy only from licensed pharmacies.

Sources

This page shows what official sources say, in plain words. It is not medical advice: your prescription and your doctor or pharmacist come first. Brand names, strengths and rules differ between countries.