FDA-filed SPL labeling · retrieved through openFDA

Magnesium Sulfate

Magnesium Sulfate is a saline laxative used to relieve occasional constipation, typically producing a bowel movement within half an hour to six hours.

Brand names Epsom SaltMagnesium Sulfate in WaterMagnesium Sulfate In DextroseEpsom SaltsPhuel +11 more
Drug classes Calculi Dissolution Agent
Rx/OTC Forms 9 Routes Intravenous · Oral; Topical · Intramuscular; Intravenous · Oral, Topical +3
Dr. Brian Staiger, PharmD, BCPS
Reviewed by Last reviewed Jul 10, 2026
🧬 Where this information comes from Click to expand

The clinical label records used on this page are FDA-filed Structured Product Labeling (SPL) retrieved through openFDA. We identified 39 clinical label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. Forms, routes, brands, labelers, strengths, and NDC product-record counts are built separately from matching FDA National Drug Code Directory records. The linked DailyMed document is a representative official source for verification, not the page’s only clinical source. View the linked label on DailyMed →

At a glance
Linked label effectiveAug 30, 2024
Clinical labels in scope 39
AvailabilityRx/OTC
Earliest approval/marketing year 1981
FDA-listed product records 340
Boxed warningNone found in compared labels
How we combine label and product data →
No current FDA shortage listed · checked Sep 21, 2026 🚨Class I recall on record
Magnesium Sulfate at a glance The quick version — the full detail is in the Patient Information Guide below.
💊
HelloPharmacist Editorial Team Bottom Line
Magnesium Sulfate is a reliable, fast-acting laxative for occasional constipation — most people see results within 30 minutes to 6 hours. Always take it with a full glass of water, and don't use it for more than a week without talking to your doctor. If you have kidney disease or take prescription medications, check with your pharmacist or doctor before using it.

📖 Magnesium Sulfate: Patient Information Guide

A plain-language walkthrough of Magnesium Sulfate — what it treats, how it works, how it’s taken, side effects, warnings and interactions. Tap any section to expand it.

🎯What it's used for

Magnesium Sulfate is used to relieve occasional constipation. Here's what that means in practice:

  • Relief of occasional irregularity (constipation)
  • Generally produces a bowel movement within 30 minutes to 6 hours
⚙️How it works

Magnesium Sulfate works by drawing water into the bowel. That extra fluid softens the stool and triggers the intestines to move, helping you go more easily and more comfortably.

💊How it's taken

Dissolve your dose in a full 8-ounce glass of water — lemon juice can be added if you don't love the taste. Drink the entire glass. You can take the full daily dose at once or split it into smaller amounts throughout the day.

  • Always follow the dosage directions on the label for your age group
  • Do not exceed the recommended daily amount
  • Children under 6 should only use this under a doctor's direction

Follow your prescriber's or pharmacist's guidance, and check the label before each use.

🤒Side effects — in detail

The label does not list specific common side effects for this product. However, watch for these warning signs that mean you should stop and call a doctor:

  • Rectal bleeding after use
  • No bowel movement at all after taking the product
  • Needing to use a laxative for more than 1 week
⚠️Warnings & precautions
  • Kidney disease: Magnesium is removed from the body by the kidneys. If your kidneys aren't working well, magnesium can build up and cause serious problems — check with your doctor before use.
  • Rectal bleeding: If you notice bleeding after use, stop immediately and see a doctor — it may be a sign of a serious condition.
  • No result after use: If the product doesn't produce a bowel movement, don't take more — talk to a doctor instead.
  • Long-term use: This is for occasional constipation only. Using it for more than 1 week without a doctor's guidance is not recommended.
  • Other symptoms: Don't use if you have stomach pain, nausea, or vomiting — or if you've noticed a sudden change in bowel habits lasting more than 2 weeks — without checking with a doctor first.
  • Overdose: In case of overdose, call Poison Control (1-800-222-1222) right away.
🔀What it interacts with

There are some important interactions to be aware of before taking this product:

  • Prescription drugs (general): Ask a doctor or pharmacist before use if you take any prescription medication — interactions are possible.
  • Magnesium-restricted diet: If your doctor has told you to limit magnesium intake, check before using this product.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

📋Before taking it
  • People with kidney disease — magnesium builds up when kidneys aren't clearing it properly
  • Anyone on a magnesium-restricted diet
  • Anyone with stomach pain, nausea, or vomiting at the time of use
  • Anyone who has had a sudden change in bowel habits lasting more than 2 weeks
  • Pregnant or breastfeeding individuals — ask a health professional first
  • Children under 6 — consult a doctor before use
  • Anyone currently taking prescription medications — check with a pharmacist or doctor first
🚑If you take too much

If too much magnesium sulfate is taken, it can be dangerous. In case of overdose, call Poison Control immediately at 1-800-222-1222, or get emergency medical help right away. Keep this product out of reach of children.

📦How to store it

Store at 20° to 25°C (68° to 77°F); excursions permitted between 15° to 30°C (59° to 86°F). Protect from freezing.

📄 Written from Magnesium Sulfate’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Every point is grounded in that labeling — nothing is invented. How we use AI →

🩺 Pharmacist Counseling Corner

Quick, plain-English answers to the questions patients ask most about Magnesium Sulfate — the kind of thing our pharmacy team would talk through with you at the counter.

How fast will this actually work?
Most people see results somewhere between 30 minutes and 6 hours after taking it. That's a pretty wide window, so just be prepared and stay close to a bathroom after your dose. Don't take a second dose just because it hasn't worked yet within the first hour — give it the full time to kick in.
Does it matter how I take it — like with food or water?
Yes, and water really matters here. You need to dissolve your dose in a full 8-ounce glass of water and drink all of it. The water helps the magnesium do its job in your intestines. If you don't like the taste, adding a little lemon juice is perfectly fine.
Can I use this every day if I have chronic constipation?
This product is designed for occasional constipation — not everyday use. If you find you need a laxative for more than one week straight, that's your sign to talk to a doctor. Relying on it regularly without guidance could mask an underlying condition that deserves proper attention.
I have kidney disease — is this safe for me?
You should talk to your doctor before using this one. Magnesium is cleared out of the body through the kidneys, so if your kidneys aren't working at full capacity, magnesium can build up to levels that cause serious problems. Your doctor can tell you if this is appropriate for you and at what amount.
What if I take a prescription medication — is that a problem?
It could be. The label recommends checking with a doctor or pharmacist before using this product if you're on any prescription drugs. Just a quick check with your pharmacist is the easiest way to make sure you're in the clear — bring your medication list or just ask at the pharmacy counter.
When should I be worried and call a doctor?
Stop use and contact your doctor if you notice any rectal bleeding, or if the product doesn't produce a bowel movement at all. Both of those can be signs of a more serious condition. Also reach out if you feel like you've been depending on this product for more than a week — that's worth a conversation with your doctor.
Is Magnesium Sulfate available over the counter?
Both — Magnesium Sulfate is sold both over the counter and by prescription, according to its FDA labeling. Lower strengths or certain forms are often available without a prescription, while higher strengths or specialized forms still require one. Ask your pharmacist which version is right for you.
When was Magnesium Sulfate first available?
Magnesium Sulfate has been available in the United States since at least 1981, based on FDA approval history (Drugs@FDA) and product marketing records.
Who makes Magnesium Sulfate?
Magnesium Sulfate is supplied by 106 manufacturers listed in the FDA NDC Directory, including Hospira, Inc., WG Critical Care, LLC, Fresenius Kabi USA, LLC.

💬 Answers drafted from Magnesium Sulfate’s FDA-approved label information, summarized in plain language with AI, and reviewed by our pharmacy team before publication. Grounded in that labeling — nothing is made up. How we use AI →

🧰 Keep exploring

💊 How Magnesium Sulfate comes

Magnesium Sulfate is available in 9 forms. Different forms and brands can have different approved uses, doses, schedules, and directions. Follow the instructions for your exact product, and do not switch forms without guidance from your prescriber or pharmacist.

Topical powder

By mouth · On the skin
Brands Epsom Salt Epsom Salts
Available strengths 2 strengths
42 FDA-listed product records

Oral powder

By mouth
Brands Epsom Salt Epsom Salts NuValu Epsom Salt
Available strengths 3 strengths
18 FDA-listed product records

Oral solution

By mouth
Brands Epsom Salt Humco Epson Salt ROYAL Epsom Salt Wish Ultra Natural Epsom Salt
Available strengths 3 strengths
9 FDA-listed product records

Topical spray

On the skin
Brands CVS muscle relief Phuel Theraworx Relief Muscle Cramp and Spasm Relief
Available strengths 2 strengths
7 FDA-listed product records

Topical cream, ointment or gel

By mouth · On the skin
Brands Epsom Salt
Available strengths 3 strengths
5 FDA-listed product records

Inhaler

On the skin
Brands Theraworx Relief Muscle Cramp and Spasm Relief
Available strengths 1 strength
3 FDA-listed product records

📊 Magnesium Sulfate across the U.S. market

How Magnesium Sulfate appears in the FDA’s National Drug Code Directory — including its dosage forms, strengths, brand names, manufacturers, and FDA-listed product records. These are directory records, not sales or prescription volume.

9
Dose forms
106
Manufacturers
29
Brand names
340
FDA-listed product records
1981
First marketed

FDA-listed product records by dose form (tablet variants merged) — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

Also listed with the FDA, not a patient dose form: Powder (5) · Crystal (4) · Granule (3) — bulk drug substance sold to compounders/manufacturers and multi-item kits. These aren’t counted in the dose-form total above.

Hospira, Inc.11%
WG Critical Care, LLC10%
Fresenius Kabi USA, LLC10%
Avadim Holdings, Inc.6%
Baxter Healthcare Corporation6%
HF Acquisition Co LLC, DBA HealthFirst4%
Other makers55%

Share of FDA-listed product records by manufacturer — FDA National Drug Code Directory. Record counts are not sales or prescription volume.

📈 How widely Magnesium Sulfate is used

A general measure of how commonly Magnesium Sulfate is prescribed, based on Medicaid — one of the largest public drug programs. The figure below is prescriptions filled in Q1–Q4 2025, summed across every form and brand of the drug.

Think of this as a proxy for how widely Magnesium Sulfate is used, drawn from freely available public data. Medicaid is just one program — these numbers don’t include Medicare, other government coverage, or commercial and cash-pay prescriptions, so real-world use is higher than what’s shown here.

148,724
Medicaid prescriptions filled (Q1–Q4 2025)
$21M gross Medicaid reimbursement (before mandatory rebates — net cost is lower)

How commonly is Magnesium Sulfate prescribed? Of the 1,596 medications we measure, Magnesium Sulfate ranks #436 by Medicaid prescriptions — more than 73% of them.

Where Magnesium Sulfate ranks among the drugs we measure · Q1–Q4 2025 · neighbors ±5

Utilization by Magnesium Sulfate product

Pick a product to see its own Medicaid numbers. Each chip is one clinical product — a specific strength & dosage form as defined by RxNorm — with brand-name and generic versions combined.

The 50 mL / 40 mg/mL injection is the most-dispensed Magnesium Sulfate product — about 35% of these Medicaid prescriptions.

50 ML magnesium sulfate 40 MG/ML Injection Most dispensed

52,275 Medicaid prescriptions (Q1–Q4 2025) 35% of Magnesium Sulfate prescriptions shown $2.4M gross reimbursement (before rebates) ≈ $46 per prescription (gross)

Summed across the 11 of 30 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658259

2 ML magnesium sulfate 500 MG/ML Injection

24,674 Medicaid prescriptions (Q1–Q4 2025) 17% of Magnesium Sulfate prescriptions shown $1.7M gross reimbursement (before rebates) ≈ $69 per prescription (gross)

Summed across the 4 of 15 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658221

100 ML magnesium sulfate 10 MG/ML Injection

21,546 Medicaid prescriptions (Q1–Q4 2025) 14% of Magnesium Sulfate prescriptions shown $968,851 gross reimbursement (before rebates) ≈ $45 per prescription (gross)

Summed across the 6 of 12 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 829757

50 ML magnesium sulfate 500 MG/ML Injection

16,936 Medicaid prescriptions (Q1–Q4 2025) 11% of Magnesium Sulfate prescriptions shown $7.9M gross reimbursement (before rebates) ≈ $468 per prescription (gross)

Summed across the 1 of 5 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658245

10 ML magnesium sulfate 500 MG/ML Injection

11,814 Medicaid prescriptions (Q1–Q4 2025) 8% of Magnesium Sulfate prescriptions shown $2M gross reimbursement (before rebates) ≈ $168 per prescription (gross)

Summed across the 1 of 13 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658244

1000 ML magnesium sulfate 40 MG/ML Injection

7,734 Medicaid prescriptions (Q1–Q4 2025) 5% of Magnesium Sulfate prescriptions shown $2.6M gross reimbursement (before rebates) ≈ $332 per prescription (gross)

Summed across the 2 of 6 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658265

20 ML magnesium sulfate 500 MG/ML Injection

7,431 Medicaid prescriptions (Q1–Q4 2025) 5% of Magnesium Sulfate prescriptions shown $3M gross reimbursement (before rebates) ≈ $405 per prescription (gross)

Summed across the 2 of 9 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658236

100 ML magnesium sulfate 40 MG/ML Injection

4,310 Medicaid prescriptions (Q1–Q4 2025) 3% of Magnesium Sulfate prescriptions shown $299,867 gross reimbursement (before rebates) ≈ $70 per prescription (gross)

Summed across the 9 of 21 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658262

500 ML magnesium sulfate 40 MG/ML Injection

1,374 Medicaid prescriptions (Q1–Q4 2025) <1% of Magnesium Sulfate prescriptions shown $73,611 gross reimbursement (before rebates) ≈ $54 per prescription (gross)

Summed across the 2 of 6 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1658264

50 ML magnesium sulfate 80 MG/ML Injection

374 Medicaid prescriptions (Q1–Q4 2025) <1% of Magnesium Sulfate prescriptions shown $45,179 gross reimbursement (before rebates) ≈ $121 per prescription (gross)

Summed across the 2 of 13 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 829734

10 ML magnesium sulfate 500 MG/ML Prefilled Syringe

153 Medicaid prescriptions (Q1–Q4 2025) <1% of Magnesium Sulfate prescriptions shown $520 gross reimbursement (before rebates) ≈ $3.40 per prescription (gross)

Summed across the 1 of 6 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 829762

magnesium sulfate 1000 MG Granules for Oral Solution

103 Medicaid prescriptions (Q1–Q4 2025) <1% of Magnesium Sulfate prescriptions shown $903 gross reimbursement (before rebates) ≈ $8.76 per prescription (gross)

Summed across the 3 of 120 listed NDC products with Medicaid activity — every brand and generic of this exact strength & form. RxNorm 1053346

Shares are of the Medicaid prescriptions shown here. Product grouping follows RxNorm (the National Library of Medicine’s drug terminology), so “one product” means one strength & dosage form regardless of manufacturer. Dollar figures are gross Medicaid reimbursement before mandatory rebates — rebates (often large, especially for brand-name drugs) are confidential, so actual net cost to Medicaid is lower than shown.

Source: Medicaid State Drug Utilization Data (CMS), aggregated by generic ingredient — summed across every NDC (all brands, strengths, salt forms and dosage forms) of Magnesium Sulfate, and across all states and both fee-for-service and managed-care claims. A general popularity signal; it excludes Medicare, commercial insurance and cash prescriptions, so it is not total U.S. use. Based on the 44 of 256 listed Magnesium Sulfate NDCs with Medicaid activity.

🔍 Compare Magnesium Sulfate products

A representative set of FDA-listed product records for Magnesium Sulfate — across manufacturers, strengths, and dosage forms, grouped by form with each product’s manufacturer and how the FDA approved it. The same medicine may be made and packaged by different companies, so a single drug can have many directory entries. (It’s also why a refill can look different — a new shape, color, or box — even though it contains the same medication.)

Showing 200 of 340 products — FDA National Drug Code Directory. See every product, package size and price: browse all 340 Magnesium Sulfate NDCs →

RxNorm Concept Web — From Ingredient to Every Form and Strength

This page starts with one ingredient concept (IN). The branches below show its dose-form concepts (SCDF), then the available clinical drug and strength concepts (SCD). Combination products remain separate concepts with their own pages.

Ingredient (IN) Magnesium Sulfate RxCUI 6585 5 dose forms · 15 strengths
  1. Dose form (SCDF) Granules for Oral Solution RxCUI 2464346 In current FDA listings
    Clinical drug / strength (SCD) 1000 MG RxCUI 1053346
  2. Dose form (SCDF) Injection RxCUI 1656665 In current FDA listings
  3. Dose form (SCDF) Oral Capsule RxCUI 1666548 No current FDA listing
    Clinical drug / strength (SCD) 100 MG RxCUI 1666549
  4. Dose form (SCDF) Topical Ointment RxCUI 376509 In current FDA listings
    Clinical drug / strength (SCD) 0.4 MG/MG RxCUI 1945074

Look up RxCUI 6585 in the RxCUI Atlas →

RxNorm is the U.S. National Library of Medicine’s normalized drug vocabulary. Its concept hierarchy can include forms that are not currently marketed; the status on each branch compares that concept with current FDA listings. RxCUIs identify vocabulary concepts, not individual packages or manufacturers.

🏷️ Sold under these brand names

Epsom Salt Magnesium Sulfate in Water Magnesium Sulfate In Dextrose Epsom Salts Phuel Theraworx Relief Muscle Cramp and Spasm Relief Magnesium Sulfate in 5% Dextrose Theraworx Relief Magnesia sulphurica NuValu Epsom Salt ROYAL Epsom Salt Equate Muscle Cramp and Spasm Relief Humco Epson Salt CVS muscle relief Wish Ultra Natural Epsom Salt Sal Inglesa EPSOM SALT

🏭 Manufacturers & labelers

Hospira, Inc. 27 WG Critical Care, LLC 23 Fresenius Kabi USA, LLC 23 Avadim Holdings, Inc. 14 Baxter Healthcare Corporation 14 HF Acquisition Co LLC, DBA HealthFirst 9 Henry Schein, Inc. 8 B. Braun Medical Inc. 8 Target Corporation 6 Whole Foods Market 6 Macco Organiques, S.r.o. 6 Mylan Institutional LLC 5 Medical Purchasing Solutions, LLC 5 Walmart, Inc 5 Vi-Jon, LLC 4 Family Dollar (FAMILY WELLNESS) 4 Meijer Distribution, Inc 4 International Wholesale Inc. 4 General Injectables and Vaccines, Inc. 4 Safeway Inc 4 Walgreens 4 Amneal Pharmaceuticals LLC 4 J C Sales 4 Retail Business Services, LLC 3

…and 16 more on the FDA NDC directory.

RxNorm drug class

Magnesium Sulfate belongs to the Osmotically acting laxatives class.

Drug family (ATC) Osmotically acting laxatives, Magnesium, Electrolyte solutions

Classified by RxNorm RxClass — the U.S. National Library of Medicine's standardized drug-classification service (Established Pharmacologic Class from the FDA, the ATC drug family from the WHO, and mechanism of action). Reference only, not medical advice.

🔬 Where this comes from

Core label, product, RxNorm, safety, and utilization data on this page come from the sources identified below. AI-written, editorial, and licensed sections are labeled separately.

📄
FDA-filed drug labels (SPL) Uses, dosing, warnings & side effects from SPL records retrieved through openFDA; the linked representative set can be verified on DailyMed. ✓ Linked label effective Aug 30, 2024
🏭
Forms, brands & labelersAggregated from ingredient-matched FDA National Drug Code Directory product records for Magnesium Sulfate.
📈
Real-world reportsThe FDA Adverse Event Reporting System (FAERS), served through openFDA.
🚨
Recalls & shortagesopenFDA drug-enforcement reports and the FDA drug-shortage database.
🧾 Clinical label set — FDA-filed SPL labels retained for Magnesium Sulfate after exact ingredient or ingredient-combination matching and applicable route/form matching
Clinical labels in scope
39
NDC products indexed
340
Distinct labelers/manufacturers represented
106
Linked representative label
Baxter Healthcare Corporation
Linked label effective
Aug 30, 2024
Composite sections available
23
Linked SPL Set ID
1bbaebd0-3f4c-467d-96fd-69cfad5a3fd3
Linked SPL Document ID
4361aea0-1a32-4c9a-86fb-d15f097eb0cc
Open the linked representative label on DailyMed ↗
NDC package records associated with this linked SPL 1

How we combine label and product data

HelloPharmacist combines public FDA and NLM records; we don’t author the underlying clinical facts. We identified 39 FDA-filed SPL label sets within the page’s selected clinical scope after exact ingredient or ingredient-combination matching and applicable route/form matching. The representative label is the starting point for the displayed reference monograph; the 12 largest stored in-scope SPL records, which may include that representative, are compared section by section, and the longest available version of each section is retained. Forms, routes, brands, labelers, product-listed strengths, and product-record counts are aggregated separately from ingredient-matched FDA NDC Directory records; package records listed above are associated with the linked SPL; and the normalized concept hierarchy comes from NLM RxNorm.

For canonical ingredient pages, bounded product-attributed indication and administration excerpts may be added to the AI evidence, and the generator is instructed to preserve available product, brand, route, and form qualifiers instead of treating one label as universal. Where a section is identified as AI-written, its plain-language text is generated from bounded label evidence. New draft drug pages remain in the admin review queue before first publication. Baxter Healthcare Corporation is the representative DailyMed label linked for verification and dates; it is not the sole source used for the page.

This is general education, not medical advice — always consult your doctor or pharmacist about your medications and any medical condition. For the exact wording of the linked representative label, view that label on DailyMed; some displayed composite sections may come from other in-scope SPL labels. Learn how we use AI and our data sources & update cadence.