magnesium oxide
Brand names: Mag-Ox
Magnesium oxide (Mag-Ox) is a mineral supplement. It helps relieve acid indigestion and upset stomach.
Drug Pricing (NADAC)
Generic Price
<$0.01/unit
Generic Available
Yes (14 manufacturers)
Pricing data from NADAC (CMS), effective December 18, 2024. Compare all drug costs →
What it does
Mag-Ox treats acid indigestion and upset stomach.
Common side effects
Diarrhea
Key warnings
There are no boxed warnings for this medication.
How It Works
Mag-Ox contains magnesium oxide, which neutralizes stomach acid. This helps to reduce discomfort caused by excess acid. It provides relief from indigestion and upset stomach.
How to Take It
Take one or two Mag-Ox tablets each day. You can take it with or without food. Do not take more than two tablets in a day. Talk to your doctor if you need more.
Pregnancy & Breastfeeding
Talk to your doctor before taking Mag-Ox if you are pregnant or breastfeeding. They can help you weigh the risks and benefits.
Missed Dose
If you miss a dose, take it as soon as you remember. Do not take more than two tablets in one day.
Storage
Store Mag-Ox at room temperature, between 59° to 86°F (15° to 30°C).
Side Effects (from patient reports)
Based on 20,513 FDA adverse event reports.
FDA Adverse Event Report Analysis
Detailed analysis of 39,831 reports from the FDA Adverse Event Reporting System (FAERS). Reports span 2002–2025.
Total Reports
39,831
Death-Related Reports
6,280
Hospitalization Reports
19,832
Top Indication
Product Used For Unknown Indication
Gender Distribution
Age Distribution
Most Reported Adverse Reactions (FAERS)
| # | Reaction | Reports |
|---|---|---|
| 1 | NAUSEA | 2,795 |
| 2 | DIARRHOEA | 2,580 |
| 3 | FATIGUE | 2,419 |
| 4 | DYSPNOEA | 2,054 |
| 5 | PNEUMONIA | 2,029 |
| 6 | OFF LABEL USE | 1,940 |
| 7 | PYREXIA | 1,829 |
| 8 | VOMITING | 1,666 |
| 9 | DEATH | 1,601 |
| 10 | HEADACHE | 1,598 |
| 11 | ANAEMIA | 1,465 |
| 12 | PAIN | 1,453 |
| 13 | DECREASED APPETITE | 1,440 |
| 14 | CONSTIPATION | 1,404 |
| 15 | DRUG INEFFECTIVE | 1,401 |
Reactions in Death Reports
Reactions in Hospitalization Reports
Source: FDA FAERS (Adverse Event Reporting System) FDA FAERS (Adverse Event Reporting System) Reports are voluntary and do not establish causation
Serious Warnings
There are no boxed warnings for this medication.
Known Drug Interactions
Antacids and Sucralfate Clinical Impact: Concomitant administration of some antacids (magnesium oxide or aluminum hydroxide) and sucralfate can delay the absorption of naproxen. Intervention: Concomitant administration of antacids such as magnesium oxide or aluminum hydroxide, and sucralfate with naproxen tablets and naproxen sodium tablets is not recommended.
Mechanism: Magnesium oxide can slow down how quickly your body absorbs naproxen into your bloodstream. This might make the naproxen take longer to start working.
What to do: It is not recommended to take these two medications at the same time. Talk to your doctor or pharmacist about how to space out your doses.
Common Questions
What is Mag-Ox used for?
How many tablets can I take each day?
Can I take Mag-Ox with food?
What should I do if I miss a dose?
How should I store Mag-Ox?
Can I take Mag-Ox if I am pregnant?
What if my symptoms do not improve?
Is Mag-Ox safe for children?
Can I take Mag-Ox with other medications?
What are the possible side effects of Mag-Ox?
What are the common side effects of magnesium oxide?
Does magnesium oxide interact with other medications?
What drug class is magnesium oxide?
Is magnesium oxide safe during pregnancy?
Related Medications in Mineral Supplement
Other drugs grouped near magnesium oxide — same-class peers and common alternatives.
ascorbic acid
Vitamin C
This medicine is a Vitamin C supplement.
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biotin
Vitamin B7
Dialyvite with Zinc is a prescription vitamin supplement.
Compare with magnesium oxide →
calcitriol
Rocaltrol
Calcitriol is a form of vitamin D that helps your body absorb and use calcium.
Compare with magnesium oxide →
calcium carbonate
Tums, Caltrate
Calcium carbonate is a medicine that can relieve heartburn and upset stomach.
Compare with magnesium oxide →
cholecalciferol
Vitamin D3
PNV-DHA is a multivitamin with minerals and essential fatty acids.
Compare with magnesium oxide →
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What the FDA Data Shows for magnesium oxide
The FDA label for magnesium oxide (sold under brand names such as Mag-Ox) classifies it as an over-the-counter product in the Mineral Supplement class. Mag-Ox treats acid indigestion and upset stomach. Official labeling lists 1 commonly reported side effect, including Diarrhea.
Post-market surveillance from the FDA Adverse Event Reporting System (FAERS) captures real-world experience. For this drug, FAERS contains 20,513 voluntary reports. The database also lists 1 documented drug interaction derived from FDA labeling, with the top-flagged interaction rated moderate severity. NADAC pricing from CMS shows a generic unit cost of <$0.01.
Report counts do not establish causation — a FAERS entry documents a temporal association, not proof that the drug produced the outcome. Widely prescribed medications naturally accumulate more reports than niche therapies, so raw totals must be interpreted alongside total exposure. Shortage status, recall history, and patent information further shape supply and switching decisions. This page summarizes public FDA data for educational purposes only and is not a substitute for professional medical advice — always consult a licensed healthcare provider before starting, stopping, or changing any medication.
Data Sources
Drug labeling: FDA Drug Labels (SPL/DailyMed). Adverse events: FDA Adverse Event Reporting System (FAERS). Pricing: CMS National Average Drug Acquisition Cost (NADAC).
FAERS reports are voluntary and do not establish causation. Drug interactions are derived from FDA labeling and clinical references. Always consult a healthcare professional before making medication decisions.
Last updated: October 21, 2025
Read our methodology — how this data is sourced, computed, and verified.
All federal data sources used on this page
- FDA Orange Book — approved drug products with therapeutic equivalence. accessdata.fda.gov/cder/ob
- FDA DailyMed — NIH-hosted drug labeling for FDA-approved meds. dailymed.nlm.nih.gov
- FDA Adverse Event Reporting System (FAERS) — post-marketing safety surveillance. fda.gov/drugs/faers
- NLM RxNorm — standardized clinical drug nomenclature. nlm.nih.gov/research/umls/rxnorm
- CMS Medicare Part B Drug Average Sales Price Files — federal drug pricing data. cms.gov/medicare/part-b-drugs/asp
- FDA Drug Shortages Database — current and resolved drug shortage tracking. accessdata.fda.gov/drugshortages