Magnesium Oxide 400 mg Tablet, 120-count
by Method Pharmaceuticals, LLC · 120 TABLET in 1 BOTTLE (58657-120-12)
NDC 58657-0120-12
🏷️ FDA NDC (as labeled)
58657-120-12
billing pads the product segment with a zero
OTC
On market
Non-controlled
🗂️ Data synced Sep 17, 2026 · sources: openFDA · FDA label (DailyMed) · FDA Orange & Purple Book · First Databank · CMS NADAC, ASP, Medicare & Medicaid · RxNorm
📋 All sources & update times →
🆔 Identity & classification
FDA NDC (as labeled)
58657-120-12
Product NDC
58657-120
11-digit billing NDC
58657012012
NCPDP billing unit
EA — each (per item)
RxCUI
198741
UNII
3A3U0GI71G
Application #
M001
SPL Set ID
0af63651-f9d9-43b9-b6f0-4878466a82e6
Established class (EPC)
Calculi Dissolution Agent; Osmotic Activity
Mechanism of action
Magnesium Ion Exchange Activity
Physiologic effect
Increased Large Intestinal Motility; Inhibition Large Intestine Fluid/Electrolyte Absorption; Inhibition Small Intestine Fluid/Electrolyte Absorption
DEA schedule
Non-controlled
Marketing category
OTC MONOGRAPH DRUG
Marketing status
On market
FDA listing status
Listed (active directory)
Marketing start
2018-07-25
Route
ORAL
Dosage form
TABLET
Substance
MAGNESIUM OXIDE
GPI-14
48400020000310
GPI class
Magnesium Oxide
GCN Seq No
078687
GCN
45064
HICL code
000609
Ingredient (HICL)
Magnesium Oxide
HIC1 code
D
Therapeutic class — broad (HIC1)
Biliary System/Gastro-Intestinal System
HIC2 code
D4
Therapeutic class — intermediate (HIC2)
Drugs Acting Principally On The Alimentary Tract
HIC3 code
D4B
Therapeutic class — specific (HIC3)
Antacids
AHFS code
56:04.00.00
AHFS class
Antacids And Adsorbents
FDB label name
MAGNESIUM OXIDE 400 MG TABLET
FDB brand name
Magnesium Oxide
Legend status
O — Over-the-counter (OTC) drug or device
Why two NDCs?
The FDA registers this code as 58657-120-12 — a 5-3-2 layout, and that's what's printed on the package and shown on DailyMed. For insurance claims, every NDC is standardized to a uniform 11-digit 5-4-2 format by adding a zero to the product segment → 58657-0120-12. Same drug, same package — only the format differs.
Where does this data come from?
Identifiers from the FDA openFDA NDC Directory and Structured Product Labeling; RxCUI from RxNorm (NLM); GPI from Medi-Span; GCN / HIC / AHFS / legend from First Databank.
🏷️ RxNorm drug class
This medicine belongs to the Magnesium compounds class.
Drug family (ATC)
Magnesium compounds, Osmotically acting laxatives, Magnesium
Where does this data come from?
Therapeutic classes from RxNorm RxClass (U.S. National Library of Medicine) — Established Pharmacologic Class (FDA), ATC drug family (WHO) and mechanism of action, matched by this product’s RxCUI.
🏭 Manufacturer & labeler
LabelerMethod Pharmaceuticals, LLC
FDA applicationM001 (OTC MONOGRAPH DRUG)
Labeler code58657
First marketedJul 2018
Product typeHuman Otc Drug
Portfolio78 products on file
The labeler markets the product; the application holder owns the FDA approval. They’re often the same company but can differ (e.g. a repackager or an authorized generic). A mailing address / phone appears here when the manufacturer includes it in the product’s FDA label (not all do).
Where does this data come from?
Labeler, application holder and registered establishment from the FDA openFDA NDC Directory and Drugs@FDA; address/contact from the product’s FDA label.
🩺 Clinical
Label name MAGNESIUM OXIDE 400 MG TABLET Ingredient Magnesium Oxide
📖 What it is MedlinePlus · NLM
Magnesium is an element your body needs to function normally. Magnesium oxide may be used for different reasons. Some people use it as an antacid to relieve heartburn, sour stomach, or acid indigestion. Magnesium oxide also may be used as a laxative for short-term, rapid emptying of the bowel (before surgery, for example). It should not be used repeatedly. Magnesium oxide also is used as a dietary supplement when the amount of magnesium in the diet is not enough. Magnesium oxide is available without a prescription.
Read the full MedlinePlus article ↗📗 Our plain-language guide HelloPharmacist
- It depends on the product you have. Some magnesium oxide tablets work as an antacid — they help relieve acid indigestion and upset stomach. Other products are sold as a dietary sup...
- What is magnesium oxide actually used for?
- When used as an antacid, you shouldn't use the maximum dose for more than two weeks in a row unless your doctor is guiding you. The magnesium supplement form is meant for daily use...
- Can I take it every day, or is it just for when I have an upset stomach?
Patient education
Supplement & herbal interactions
Where does this data come from?
Plain-language summary from MedlinePlus (U.S. National Library of Medicine); supplement & herbal interactions and nutrient depletion data from the Natural Medicines database; our full guide is HelloPharmacist editorial content.
💬 Questions about Magnesium Oxide?
Ask a pharmacist →
Ask a licensed pharmacist directly — free, answered by our team.
💊 What it looks like
Color
white
ShapeRound
Imprint120
Size11 mm
ScoringNot scored
One label can cover several strengths, so colors may be combined — always confirm a loose pill against the dispensed prescription label or a pharmacist.
Where does this data come from?
Physical description (imprint, shape, color, scoring, coating) from this product’s FDA Structured Product Labeling (SPL), mirrored from DailyMed / openFDA.
🧪 Inactive Ingredients / Excipients
Inactive ingredients, also called excipients, are components of the drug product other than the active ingredient. They may include fillers, dyes, coatings, preservatives, flavors, or other formulation ingredients.
💡 Tap an ingredient (hover on desktop) to see what it is and why it’s used.
-
UNII OP1R32D61U
Microcrystalline cellulose is a purified form of cellulose, a natural fiber from plant sources. It acts as a binder and filler in tablets and capsules, helping hold ingredients together and give the medicine its shape and size.
-
UNII M28OL1HH48
Croscarmellose sodium is a plant-based substance derived from cellulose. It acts as a disintegrant, helping tablets and capsules break down quickly in the digestive system so the medicine can be absorbed.
-
UNII ETJ7Z6XBU4
Silicon dioxide is a naturally occurring mineral used as a glidant and anti-caking agent. It helps powder ingredients flow smoothly and prevents clumping during manufacturing and storage.
-
UNII 4ELV7Z65AP
Stearic acid is a fatty acid derived from plant or animal sources. It acts as a binder and lubricant in tablets and capsules, helping them hold together and flow smoothly during manufacturing.
4 inactive ingredients listed in the exact product block matched to this NDC.
The official label also statesCroscarmellose Sodium, Microcrystalline Cellulose, Silicon Dioxide, and Stearic Acid.
Label-section wording can be broader than the structured product block and may mention additional formulation ingredients.
Where does this data come from?
Data sourced from official FDA Structured Product Labeling (SPL) via DailyMed —
ingredient classCode="IACT" elements from the exact product block matched by this NDC. Label-section narrative from DailyMed / the openFDA label index is shown separately when available.Inactive ingredient FAQ
Are inactive ingredients the same for every manufacturer?
No. Inactive ingredients can differ by manufacturer, dosage form, strength, and package / product version.
Why might an inactive ingredient be missing?
Some SPLs do not provide a complete structured inactive-ingredient list, and older or unusual labels may only include the information in narrative text.
Can inactive ingredients matter?
Yes. They can matter for allergies, intolerances, dyes, gluten / lactose concerns, preservatives, and formulation differences — but confirm with a pharmacist or the manufacturer when it’s clinically important.
💲 Pricing
A drug doesn't have one price. Each row is a different public payment system, and none is what you'd pay at the counter — that depends on your insurance. The ⓘ on each row explains what it measures.
| Price system | Per ea | Per package |
|---|---|---|
| Retail pharmacies payNADAC · weekly | $0.035 | $4.16 / 120 tablets |
| Medicaid paysCMS SDUD · 12 mo | $0.1989 | $23.87 / 120 tablets |
| Medicare drug plans payPart D · quarterly | No Part D plan price is available for this NDC in our data. | |
NADAC price history (per ea) — tap or hover for the price & month
▼ Down 10% over the last 24 months.
Where does this data come from?
NADAC (National Average Drug Acquisition Cost) is the CMS weekly pharmacy-acquisition-cost survey — what pharmacies pay. ASP (Average Sales Price) is the CMS Medicare Part B drug-payment file, published quarterly. Medicaid pays is computed by us from CMS State Drug Utilization Data (total reimbursed ÷ units, trailing 12 months) — gross of rebates and inclusive of dispensing fees, so it reflects what Medicaid paid, not an acquisition cost. Medicare drug plans pay is the median negotiated point-of-sale unit cost across plans listing this NDC in the CMS quarterly Prescription Drug Plan pricing files, before rebates. The VA pays is the federal contract price (FSS, and the statutory Big 4 ceiling where listed) from the VA National Acquisition Center pharmaceutical price file. All are free public government data; each measures a different payer, so the figures are not directly comparable.
🔁 Therapeutic equivalents
| Product | Labeler | Pack | NADAC/unit | TE | Status | Price vs. this |
|---|---|---|---|---|---|---|
| Magnesium Oxide 400 mg 00603-0209-22 | Endo | 120 tablets | $0.035 | — | Availability likely | — |
| Magnesium Oxide 400 mg 24689-0132-01 | APNAR | 120 tablets | $0.035 | — | Availability likely | — |
| Magnesium Oxide 400 mgthis 58657-0120-12 | Method | 120 tablets | $0.035 | — | Availability likely | — |
| Magnesium Oxide 400 mg 69367-0298-20 | Westminster | 120 tablets | $0.035 | — | Availability likely | — |
| Magnesium Oxide 400 mg 81033-0027-01 | Kesin | 1000 tablets | $0.035 | — | Availability likely | — |
| Magnesium Oxide 400 mg 10135-0786-62 | Marlex | 120 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 50090-7432-00 | A-S | 120 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 54738-0973-12 | Richmond | 120 tablets | — | — | Discontinued | — |
| Magnesium Oxide 400 mg 63629-1126-01 | Bryant | 120 tablets | — | — | Discontinued | — |
| Magnesium Oxide 400 mg 63629-9420-01 | Bryant | 120 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400mg 400 mg 69168-0174-06 | Allegiant | 120 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 71335-1960-01 | Bryant | 60 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 71610-0172-60 | Aphena | 90 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 71610-0182-60 | Aphena | 90 tablets | — | — | FDA listed | — |
| Magnesium Oxide 400 mg 72162-1648-04 | Bryant | 120 tablets | — | — | FDA listed | — |
| Magnesium Oxide 241.3 mg/1000mg 84447-0001-12 | Belleview | 120 mg | — | — | FDA listed | — |
About this product: other versions of the same ingredient, strength and form are listed above, least expensive first, with FDA equivalence ratings where available.
Where does this data come from?
Equivalents are other NDCs of the same ingredient, form and route from the openFDA NDC Directory, ranked least-expensive-first by NADAC. Therapeutic-equivalence (AB) ratings come from the FDA Orange Book; biologics use the FDA Purple Book for biosimilar & interchangeable status.
⏳ Availability & generic status
🏛️
2018
On the market since
Jul 2018
📍
2026
Currently FDA-listed
8 years listed
🔒
·
No generic listed yet
brand only
ℹ️No FDA-approved generic found
We did not find an FDA-approved generic match for this exact strength, form and route.
Where does this data come from?
Patents and exclusivity from the FDA Orange Book (small-molecule drugs), refreshed from public FDA data. Generic launch timing is an estimate, not a guarantee.
🗺️ Medicaid utilization & spend
📍 This exact package only: Medicaid data is reported per full 11-digit NDC — labeler, product and pack size — so every number here is for 58657-0120-12, not the drug overall. Other pack sizes report separately.
💊 Pharmacy benefit only: These are Medicaid outpatient pharmacy claims, billed by NDC. They exclude the medical benefit — clinic- or hospital-administered drugs billed under HCPCS J-codes — so drugs used mostly that way (e.g. Avastin, Lucentis, Keytruda) can look low or missing here. That’s expected, not an error.
📅 Q1 2025 – Q4 2025 · 4 quarters of data
ⓘ The newest quarter is usually incomplete when first published; states restate recent quarters in later CMS releases, so the latest figures typically revise upward. State coverage-policy changes can also shift quarter-to-quarter totals.
Prescriptions last 4 qtrs
34.5K
Units reimbursed last 4 qtrs
1.7M
Gross reimbursed last 4 qtrs
$342.1K
Avg / prescription
$9.91
Avg / unit
$0.1989
Latest quarter Q4 2025
8.6KRx
Medicaid pays / ea
$0.1989
gross reimbursed
vs
NADAC / ea
$0.0347
acquisition cost
=
Spread
+$0.1642
+473% vs cost
What Medicaid paid per ea (before rebates; includes the pharmacy’s dispensing fee) compared with NADAC — the average price pharmacies pay to buy the drug. A positive spread means Medicaid reimbursed more than the purchase price, before manufacturer rebates.
Fee-for-service vs managed care ⓘ
Fee-for-service · 28,923 Rx Managed care · 5,595 Rx
State Medicaid map
Units reimbursed · per 100k residents
22.624,509
gray = no data reported ⓘ
Colors are per 100,000 residents, so big states don’t automatically dominate. Tap or hover a state for its actual totals.
Tap or hover a state
…for its Medicaid breakdown
Prescriptions—
Units—
Reimbursed—
🏆 Top states by units · per 100k residents
National units — by quarter
💵 About the dollar figures: “reimbursed” is what Medicaid paid pharmacies before confidential manufacturer rebates, so the program’s real net cost is lower than these numbers. Fee-for-service and managed-care claims are combined unless split above. Source: CMS State Drug Utilization Data; per-100k rates use 2023 Census population estimates.
🔬 Reported adverse events (FAERS)
Read carefully: FAERS reports are voluntary and unverified. Counts are not incidence, do not establish causation, are subject to reporting bias, and cannot be used to compare one drug to another. Shown for signal context only. Reports for Magnesium Oxide — the ingredient across all brands.
Top reported reactions
Age at onset
Reporter sex
Male · 43%
Female · 57%
Unknown · 0%
Serious outcomes
Reports over time (by year) — tap or hover for the count & year
Most recent year is provisional (FAERS lags ~3 months).
Where does this data come from?
Adverse-event reports from the FDA Adverse Event Reporting System (FAERS) via openFDA. FAERS reports are voluntary and unverified — counts are not incidence and don’t establish causation.
📦 Packaging — all sizes for this product
| Package NDC | Description | Marketing start | Status |
|---|---|---|---|
| 58657-0120-12 You're viewing this | 120 TABLET in 1 BOTTLE (58657-120-12) | 2018-07-25 | Active |
📄 FDA label — Drug Facts FDA SPL
The complete FDA label for this product — the official Drug Facts labeling, verbatim, section by section. Jump with a chip, search within the label, or expand everything.
🎯 Indications and Usage
⏱️ Dosage and Administration
⚠️ Warnings
📦 Storage and Handling
🧪 Active Ingredient
🧪 Inactive Ingredients
🎯 Purpose
🎯 Indications and Usage ▾
Use relieves: ■ acid indigestion ■ upset stomach
⏱️ Dosage and Administration ▾
Directions take one or two antacid tablets daily. Do not exceed two tablets unless directed by a physician.
⚠️ Warnings ▾
Warnings Ask a doctor before use if you have kidney disease you are taking a prescription drug (antacids may interact with certain prescription drugs) you are pregnant or breast feeding. Do not take more than 2 tablets in a 24 hour period. May have a laxative effect. Keep out of reach of children.
📦 Storage and Handling ▾
Other information Store at controlled room temperature 15° to 30°C (59° to 86°F). Tamper evident, do not use if imprinted safety seal under cap is broken or missing.
🧪 Active Ingredient ▾
Active ingredient Magnesium Oxide 400 mg (241.3 mg Elemental Magnesium)
🧪 Inactive Ingredients ▾
Inactive ingredients Croscarmellose Sodium, Microcrystalline Cellulose, Silicon Dioxide, and Stearic Acid.
🎯 Purpose ▾
Purpose Antacid
No label section mentions that — try another word, or open the full label on DailyMed below.
Source: FDA Structured Product Labeling, mirrored from DailyMed / openFDA.
Prefer the government’s original formatting? View this label on DailyMed ↗
For educational and professional reference only — not medical advice. Pricing reflects published
NADAC and CMS ASP (free public data) and may differ from your acquisition cost; always verify before billing or dispensing.