Magnesium 250 mg Ingredients & Drug Interactions
by GNC
What is this page for?
First and foremost: checking Magnesium 250 mg against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.
Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy
Magnesium 250 mg is a dietary supplement by GNC with 1 active ingredient. Its ingredients are commonly taken for preventing or treating magnesium deficiency, constipation, muscle cramps.Based on those ingredients, 295 medications have a known interaction with it, the most serious rated major. The ingredients most likely to interact are Magnesium. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.
Check Your Meds Against Magnesium 250 mg by GNC
Ask about any prescription or over-the-counter medication and we check it for interactions with Magnesium 250 mg by GNC — and tell you which ingredient is responsible.
AI summaries are generated from our interaction database for education only — always confirm with your pharmacist. How we use AI
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HelloPharmacist Scorecard of Magnesium 250 mg by GNC
Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.
What’s inside
Full disclosure
This product contains one active ingredient: magnesium at 250 mg per tablet. Magnesium is an essential mineral your body uses for muscle and nerve function, bone health, and energy production.
The tablet also includes inactive ingredients — microcrystalline cellulose, hydroxypropyl methylcellulose, polyethylene glycol, talc, magnesium stearate, silicon dioxide, titanium dioxide, vegetable acetoglycerides, and polysorbate 80 — which are fillers, binders, and coating materials.
Does it work?
Strong evidence
Magnesium 250 mg by GNC is effective for indigestion (dyspepsia), constipation, low magnesium levels (hypomagnesemia), and pre-eclampsia in pregnancy when used under medical supervision. These ratings come from clinical evidence in our data.
How safe is it?
Well-documented data
Magnesium is generally well tolerated when taken at recommended doses. The most common side effects from oral magnesium are diarrhea, stomach irritation, nausea, and vomiting.
Magnesium is needed during pregnancy, but supplements should only be used under your doctor's guidance. For breastfeeding, dietary amounts are fine, but talk with your doctor before taking a supplement.
In rare cases, very high doses have caused serious effects; stay within recommended amounts.
Meds to double-check
Major interaction found
Before taking this product, double-check with your doctor or pharmacist if you use levodopa/carbidopa for Parkinson's, skeletal muscle relaxants, potassium-sparing diuretics, calcium channel blockers, sulfonylureas for diabetes, quinolone antibiotics, or bisphosphonates. Magnesium can reduce how well some of these work or increase their effects.
The bottom line
Scorecard at a glanceFully disclosed formula with clinical evidence supporting its stated purpose. Major medication interactions have been identified, and safety information is well characterized.
GNC Magnesium 250 mg may help if you have indigestion, constipation, or low magnesium — or during pregnancy if your doctor recommends it. If you take levodopa/carbidopa, muscle relaxants, diuretics, blood pressure medication, diabetes medication, antibiotics, or bone medications, check with your doctor or pharmacist before starting this supplement.
They can make sure magnesium won't interfere with your treatment.
Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI
Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jun 24, 2020.
This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed
General information
Key facts about Magnesium 250 mg, straight from the product label.
| Brand | GNC |
|---|---|
| Barcode (UPC) | 048107205805 |
| Net contents | 90 Vegetarian Tablet(s) |
| Market status | On market |
| Date entered into DSLD | Jun 24, 2020 |
| DSLD ID | 224666 |
| Product type | Mineral |
| Supplement form | Tablet Or Pill |
| Dietary claims / uses | All Other, Structure/Function |
| Intended target group(s) | Adult (18 - 50 Years), Kosher, Gluten Free, Dairy Free, Sugar Free |
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.
Supplement Facts
The label details for Magnesium 250 mg by GNC, sourced from the NIH Dietary Supplement Label Database.
Supplement Facts
| Ingredient | Amount | % DV |
|---|---|---|
| Magnesium | 250 mg | 60% |
Other ingredients: Microcrystalline Cellulose, Hydroxypropyl Methylcellulose, Polyethylene Glycol, Talc, Magnesium Stearate, Silicon Dioxide, Titanium Dioxide, Vegetable Acetoglycerides, Polysorbate 80
Tap any ingredient to jump to its full detail below.
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
Precautions
Keep out of reach of children.
Storage
Store in a cool, dry place.
Formulation
Essential for strong bones & teeth Necessary for muscle & nerve function
All mineral amounts shown are elemental. Potency verified by GNC procedure #4000. Conforms to USP <2091> for weight. Meets USP <2040> disintegration.
No sugar, no starch, no artificial flavors, sodium free, no wheat, gluten free, no corn, no soy, no dairy.
General Statements
90-day supply
FDA Statement of Identity
Dietary Supplement
Suggested/Recommended/Usage/Directions
Directions: As a dietary supplement, take one tablet daily.
Seals/Symbols
Ko Kosher Service
Formula
Ko Kosher Service
FDA Disclaimer Statement
These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Is this label outdated? Report a formula or label change and our pharmacy team will review it.
Magnesium 250 mg by GNC label
The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.
Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.
View the full label (PDF)The Ingredients in Magnesium 250 mg by GNC
This is the 1 active ingredient this product is made of. Select it to open its full monograph.
Serving size1 Tablet(s) Dosage formTablet Or Pill Amounts shown are per serving.
Magnesium
Interacts with295 drugs
Magnesium is an essential mineral your body needs for muscles, nerves, blood pressure, and many other functions, and supplements are useful for preven...
Magnesium monograph & interactionsOther (inactive) ingredients: Microcrystalline Cellulose, Hydroxypropyl Methylcellulose, Polyethylene Glycol, Talc, Magnesium Stearate, Silicon Dioxide, Titanium Dioxide, Vegetable Acetoglycerides, Polysorbate 80. These complete the product’s ingredient list but are not active constituents.
Magnesium 250 mg by GNC Drug Interactions
HelloPharmacist Interaction Report
GNC Magnesium 250 mg interacts with several medication types through its single active ingredient.
The most serious concern is with levodopa/carbidopa (Sinemet), a Parkinson's medication — magnesium can cut levodopa levels by about a third and carbidopa levels by as much as 81%, potentially reducing how well the medication works.
Read the full breakdown — every affected drug type, severity by severity
Moderate interactions also occur with skeletal muscle relaxants (magnesium may speed up their effects and how long they last), potassium-sparing diuretics (which may raise your magnesium levels), calcium channel blockers used for blood pressure (additive effects are possible), and sulfonylureas for diabetes (magnesium can boost their effects and hypoglycemia risk). Magnesium also reduces absorption of quinolone antibiotics and bisphosphonates used for bone health, and it can interfere with how acid-reducing medications work.
If you take any of these medication types, check your exact drugs with the search tool on this page before starting magnesium. Altogether, these interactions span 295 individual medications.
Check your own medications below · Editorial policy · How we use AI
Want to check YOUR meds against Magnesium 250 mg?
Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.
Go to the checkerIngredients driving the most interactions
Individual Drug Interactions
The ingredients in Magnesium 250 mg interact with 295 drugs. Click any drug to see the details.
1 of the 1 ingredient in Magnesium 250 mg interact with drugs. Each result below shows which ingredient is responsible. Magnesium
Benserazide, LevodopaMadopar, Prolopa
How Benserazide, Levodopa interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Benserazide, Levodopa interactionCarbidopaLodosyn
How Carbidopa interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Carbidopa interactionCarbidopa, LevodopaDhivy, Rytary, Sinemet, Sinemet CR
How Carbidopa, Levodopa interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Carbidopa, Levodopa interactionCarbidopa, Levodopa, EntacaponeStalevo
How Carbidopa, Levodopa, Entacapone interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Carbidopa, Levodopa, Entacapone interactionLevodopaInbrija, Larodopa
How Levodopa interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Levodopa interactionLevodopa, CarbidopaDuodopa
How Levodopa, Carbidopa interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumLevodopa/carbidopa (sinemet) Major
Interaction Summary
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Read the full Magnesium + Levodopa, Carbidopa interactionAcetaminophen, ChlorzoxazoneAcetazone Forte, Extra Strength Tylenol Aches & Strains, Parafon Forte
How Acetaminophen, Chlorzoxazone interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Acetaminophen, Chlorzoxazone interactionAcetaminophen, Chlorzoxazone, CodeineAcetazone Forte C8, Parafon Forte C8
How Acetaminophen, Chlorzoxazone, Codeine interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Acetaminophen, Chlorzoxazone, Codeine interactionAcetaminophen, Codeine, MethocarbamolAcetaminophen, Codeine, Methocarbamol, Robaxacet 8
How Acetaminophen, Codeine, Methocarbamol interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Acetaminophen, Codeine, Methocarbamol interactionAcetaminophen, MethocarbamolRobaxacet
How Acetaminophen, Methocarbamol interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Acetaminophen, Methocarbamol interactionAcetaminophen, OrphenadrineOrfenagesic
How Acetaminophen, Orphenadrine interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Acetaminophen, Orphenadrine interactionAcetohexamideDymelor
How Acetohexamide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSulfonylureas Moderate
Interaction Summary
Magnesium increases the systemic absorption of sulfonylureas, increasing their effects and side effects.
Read the full Magnesium + Acetohexamide interactionAlcuroniumAlcuronium
How Alcuronium interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumSkeletal Muscle Relaxants Moderate
Interaction Summary
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Read the full Magnesium + Alcuronium interactionAlendronateBinosto, Fosamax
How Alendronate interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumBisphosphonates Moderate
Interaction Summary
Magnesium can decrease absorption of bisphosphonates.
Read the full Magnesium + Alendronate interactionAlendronate Sodium
How Alendronate Sodium interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumBisphosphonates Moderate
Interaction Summary
Magnesium can decrease absorption of bisphosphonates.
Read the full Magnesium + Alendronate Sodium interactionAlendronate Sodium, CholecalciferolFosamax Plus D
How Alendronate Sodium, Cholecalciferol interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumBisphosphonates Moderate
Interaction Summary
Magnesium can decrease absorption of bisphosphonates.
Read the full Magnesium + Alendronate Sodium, Cholecalciferol interactionAlginic Acid, Aluminum HydroxideRafton
How Alginic Acid, Aluminum Hydroxide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAntacids Moderate
Interaction Summary
Use of acid reducers may reduce the laxative effect of magnesium oxide.
Read the full Magnesium + Alginic Acid, Aluminum Hydroxide interactionAluminum HydroxideAlu-Cap, Amphojel, Gaviscon
How Aluminum Hydroxide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAntacids Moderate
Interaction Summary
Use of acid reducers may reduce the laxative effect of magnesium oxide.
Read the full Magnesium + Aluminum Hydroxide interactionAluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium HydroxideAscriptin Codeine #2
How Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium Hydroxide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAnticoagulant/antiplatelet Drugs, Antacids Moderate
Interaction Summary
Theoretically, magnesium may have antiplatelet effects, but the evidence is conflicting.
Read the full Magnesium + Aluminum Hydroxide, Aspirin, Codeine Phosphate, Magnesium Hydroxide interactionAluminum Hydroxide, Aspirin, Magnesium HydroxideAscriptin
How Aluminum Hydroxide, Aspirin, Magnesium Hydroxide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAnticoagulant/antiplatelet Drugs, Antacids Moderate
Interaction Summary
Theoretically, magnesium may have antiplatelet effects, but the evidence is conflicting.
Read the full Magnesium + Aluminum Hydroxide, Aspirin, Magnesium Hydroxide interactionAluminum Hydroxide, Magnesium Hydroxide (otc Drug)Maalox, Mucogel
How Aluminum Hydroxide, Magnesium Hydroxide (otc Drug) interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAntacids Moderate
Interaction Summary
Use of acid reducers may reduce the laxative effect of magnesium oxide.
Read the full Magnesium + Aluminum Hydroxide, Magnesium Hydroxide (otc Drug) interactionAluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug)Mylanta
How Aluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug) interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAntacids Moderate
Interaction Summary
Use of acid reducers may reduce the laxative effect of magnesium oxide.
Read the full Magnesium + Aluminum Hydroxide, Magnesium Hydroxide, Simethicone (otc Drug) interactionAluminum, Magnesium (otc Drug)Almagel
How Aluminum, Magnesium (otc Drug) interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAntacids Moderate
Interaction Summary
Use of acid reducers may reduce the laxative effect of magnesium oxide.
Read the full Magnesium + Aluminum, Magnesium (otc Drug) interactionAmikacinAmikin, Arikayce
How Amikacin interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumAminoglycoside Antibiotics Moderate
Interaction Summary
Concomitant use of aminoglycoside antibiotics and magnesium can increase the risk for neuromuscular weakness.
Read the full Magnesium + Amikacin interactionAmilorideAmilamont, Midamor
How Amiloride interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumPotassium-sparing Diuretics Moderate
Interaction Summary
Potassium-sparing diuretics decrease excretion of magnesium, possibly increasing magnesium levels.
Read the full Magnesium + Amiloride interactionAmiloride, HydrochlorothiazideAmil-Co, Amilzide, Moduret 25, Moduretic
How Amiloride, Hydrochlorothiazide interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumPotassium-sparing Diuretics Moderate
Interaction Summary
Potassium-sparing diuretics decrease excretion of magnesium, possibly increasing magnesium levels.
Read the full Magnesium + Amiloride, Hydrochlorothiazide interactionAmlodipineNorliqva
How Amlodipine interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumCalcium Channel Blockers Moderate
Interaction Summary
Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
Read the full Magnesium + Amlodipine interactionAmlodipine BenzoateKaterzia
How Amlodipine Benzoate interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumCalcium Channel Blockers Moderate
Interaction Summary
Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
Read the full Magnesium + Amlodipine Benzoate interactionAmlodipine BesilateIstin
How Amlodipine Besilate interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumCalcium Channel Blockers Moderate
Interaction Summary
Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
Read the full Magnesium + Amlodipine Besilate interactionAmlodipine BesylateNorvasc
How Amlodipine Besylate interacts with Magnesium 250 mg — through 1 ingredient. Tap an ingredient for the detail:
MagnesiumCalcium Channel Blockers Moderate
Interaction Summary
Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
Read the full Magnesium + Amlodipine Besylate interactionEach ingredient & the kinds of drugs it affects
For each ingredient in Magnesium 250 mg with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.
Magnesium
Levodopa/Carbidopa (Sinemet)
Magnesium can reduce the bioavailability of levodopa/carbidopa.
Clinical research in healthy volunteers shows that taking magnesium oxide 1000 mg with levodopa 100 mg/carbidopa 10 mg reduces the area under the curve (AUC) of levodopa by 35% and of carbidopa by 81%. In vitro and animal research shows that magnesium produces an alkaline environment in the digestive tract, which might lead to degradation and reduced bioavailability of levodopa/carbidopa.
Aminoglycoside Antibiotics
Concomitant use of aminoglycoside antibiotics and magnesium can increase the risk for neuromuscular weakness.
Both aminoglycosides and magnesium reduce presynaptic acetylcholine release, which can lead to neuromuscular blockade and possible paralysis. This is most likely to occur with high doses of magnesium given intravenously.
Antacids
Use of acid reducers may reduce the laxative effect of magnesium oxide.
A retrospective analysis shows that, in the presence of H2 receptor antagonists (H2RAs) or proton pump inhibitors (PPIs), a higher dose of magnesium oxide is needed for a laxative effect. This may also occur with antacids. Under acidic conditions, magnesium oxide is converted to magnesium chloride and then to magnesium bicarbonate, which has an osmotic laxative effect. By reducing acidity, antacids may reduce the conversion of magnesium oxide to the active bicarbonate salt.
Bictegravir/Emtricitabine/Tenofovir Alafenamide (Biktarvy)
Magnesium might decrease levels of bictegravir/emtricitabine/tenofovir alafenamide by reducing its absorption.
Advise patients that bictegravir/emtricitabine/tenofovir alafenamide should be taken at least 2 hours before or 6 hours after magnesium containing products.
Bisphosphonates
Magnesium can decrease absorption of bisphosphonates.
Cations, including magnesium, can decrease bisphosphonate absorption. Advise patients to separate doses of magnesium and these drugs by at least 2 hours.
Calcium Channel Blockers
Magnesium can have additive effects with calcium channel blockers, although evidence is conflicting.
Magnesium inhibits calcium entry into smooth muscle cells and may therefore have additive effects with calcium channel blockers. Severe hypotension and neuromuscular blockades may occur when nifedipine is used with intravenous magnesium, although some contradictory evidence suggests that concurrent use of magnesium with nifedipine does not increase the risk of neuromuscular weakness. High doses of magnesium could theoretically have additive effects with other calcium channel blockers.
Digoxin
Magnesium salts may reduce absorption of digoxin.
Clinical evidence suggests that treatment with oral magnesium hydroxide or magnesium trisilicate reduces absorption of digoxin from the intestines. This may reduce the blood levels of digoxin and decrease its therapeutic effects.
Potassium-Sparing Diuretics
Potassium-sparing diuretics decrease excretion of magnesium, possibly increasing magnesium levels.
Potassium-sparing diuretics also have magnesium-sparing properties, which can counteract the magnesium losses associated with loop and thiazide diuretics. Theoretically, increased magnesium levels could result from concomitant use of potassium-sparing diuretics and magnesium supplements.
Quinolone Antibiotics
Magnesium decreases absorption of quinolones.
Magnesium can form insoluble complexes with quinolones and decrease their absorption. Advise patients to take these drugs at least 2 hours before, or 4 to 6 hours after, magnesium supplements.
Skeletal Muscle Relaxants
Parenteral magnesium alters the pharmacokinetics of skeletal muscle relaxants, increasing their effects and accelerating the onset of effect.
Parenteral magnesium shortens the time to onset of skeletal muscle relaxants by about 1 minute and prolongs the duration of action by about 2 minutes. Magnesium potentiates the effects of skeletal muscle relaxants by decreasing calcium-mediated release of acetylcholine from presynaptic nerve terminals, reducing postsynaptic sensitivity to acetylcholine, and having a direct effect on the membrane potential of myocytes. Magnesium also has vasodilatory actions and increases cardiac output, allowing a greater amount of muscle relaxant to reach the motor end plate. A clinical study found that low-dose rocuronium (0.45 mg/kg), when given after administration of magnesium 30 mg/kg over 10 minutes, has an accelerated onset of effect, which matches the onset of effect seen with a full-dose rocuronium regimen (0.6 mg/kg). In another clinical study, onset times for rocuronium doses of 0.3, 0.6, and 1.2 mg/kg were 86, 76, and 50 seconds, respectively, when given alone, but were reduced to 66, 44, and 38 seconds, respectively, when the doses were given after a 15-minute infusion of magnesium sulfate 60 mg/kg. Giving intraoperative intravenous magnesium sulfate, 50 mg/kg loading dose followed by 15 mg/kg/hour, reduces the onset time of rocuronium, enhances its clinical effects, reduces the dose of intraoperative opiates, and prolongs the spontaneous recovery time. It does not affect the activity of subsequently administered neostigmine.
Sulfonylureas
Magnesium increases the systemic absorption of sulfonylureas, increasing their effects and side effects.
Clinical research shows that administration of magnesium hydroxide with glyburide increases glyburide absorption, increases maximal insulin response by 35-fold, and increases the risk of hypoglycemia, when compared with glyburide alone. A similar interaction occurs between magnesium hydroxide and glipizide. The mechanism of this effect appears to be related to the elevation of gastrointestinal pH by magnesium-based antacids, increasing solubility and enhancing absorption of sulfonylureas.
Tetracycline Antibiotics
Magnesium decreases absorption of tetracyclines.
Magnesium can form insoluble complexes with tetracyclines in the gut and decrease their absorption and antibacterial activity. Advise patients to take these drugs 1 hour before or 2 hours after magnesium supplements.
Anticoagulant/Antiplatelet Drugs
Theoretically, magnesium may have antiplatelet effects, but the evidence is conflicting.
In vitro evidence shows that magnesium sulfate inhibits platelet aggregation, even at low concentrations. Some preliminary clinical evidence shows that infusion of magnesium sulfate increases bleeding time by 48% and reduces platelet activity. However, other clinical research shows that magnesium does not affect platelet aggregation, although inhibition of platelet-dependent thrombosis can occur.
Gabapentin (Neurontin)
Gabapentin absorption can be decreased by magnesium.
Clinical research shows that giving magnesium oxide orally along with gabapentin decreases the maximum plasma concentration of gabapentin by 33%, time to maximum concentration by 36%, and area under the curve by 43%. Advise patients to take gabapentin at least 2 hours before, or 4 to 6 hours after, magnesium supplements.
Sevelamer (Renagel, Renvela)
Sevelamer may increase serum magnesium levels.
In patients on hemodialysis, sevelamer use was associated with a 0.28 mg/dL increase in serum magnesium. The mechanism of this interaction remains unclear.
Brand information
Manufacturer and brand details for Magnesium 250 mg, from the product label.
GNC
See all GNC products- Name
- General Nutrition Corporation
- City
- Pittsburgh
- State
- PA
- ZipCode
- 15222
- Phone Number
- 1-888-462-2548
- Web Address
- gnc.com
Magnesium 250 mg by GNC: Common Questions
Does Magnesium 250 mg by GNC interact with any medications?
How can one product interact with so many drugs?
Where does this information come from?
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Can I take this if I'm breastfeeding?
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Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy
Not sure if Magnesium 250 mg is safe with your meds?
Our pharmacists answer your medication & supplement questions — free.
Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.
The Full Monographs Behind Magnesium 250 mg’s Ingredients
Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.
Sources & How We Checked
Magnesium 250 mg's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.
- NIH Dietary Supplement Label Database (DSLD) — The official product label on file for this supplement.
- Natural Medicines (Therapeutic Research Center) — Evidence-graded clinical reference behind the ingredient interaction data.
Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.
The 82 references behind this product’s interaction data
Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.
Magnesium 82 references
- Rodin SM, Johnson BF. Pharmacokinetic interactions with digoxin. Clin Pharmacokinet 1988;15:227-44.
- Covington TR, et al. Handbook of Nonprescription Drugs. 11th ed. Washington, DC: American Pharmaceutical Association, 1996.
- Dahle LO, Berg G, Hammar M, et al. The effect of oral magnesium substitution on pregnancy-induced leg cramps. Am J Obstet Gynecol 1995;173:175-80. PubMed
- Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
- Peikert A, Wilimzig C, Kohne-Volland R. Prophylaxis of migraine with oral magnesium: results from a prospective, multi-center, placebo-controlled and double-blind randomized study. Cephalalgia 1996;16:257-63. PubMed
- Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. Washington, DC: National Academy Press, 1999. Available at: http://books.nap.edu/books/0309063507/html/index.html.
- Birrer RB, Shallash AJ, Totten V. Hypermagnesemia-induced fatality following epsom salt gargles. J Emerg Med 2002;22:185-8. PubMed
- Ryan MP. Diuretics and potassium/magnesium depletion. Directions for treatment. Am J Med 1987;82:38-47.. PubMed
- Hollifield JW. Magnesium depletion, diuretics, and arrhythmias. Am J Med 1987;82:30-7.. PubMed
- Heidenreich O. Mode of action of conventional and potassium-sparing diuretics--aspects with relevance to Mg-sparing effects. Magnesium 1984;3:248-56..
- Pfaffenrath V, Wessely P, Meyer C, et al. Magnesium in the prophylaxis of migraine--a double-blind placebo-controlled study. Cephalalgia 1996;16:436-40.. PubMed
- Wang F, Van Den Eeden SK, Ackerson LM, et al. Oral magnesium oxide prophylaxis of frequent migrainous headache in children: a randomized, double-blind, placebo-controlled trial. Headache 2003;43:601-10.. PubMed
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