Magnesium 200mg Tablets
It is used to treat or prevent low magnesium levels.
Drug Class
Mineral supplement; Electrolyte; Antacid; Laxative
Pharmacologic Class
Essential mineral; Electrolyte replacement; Osmotic agent
Pregnancy Category
Category B
FDA Approved
Jan 1970
DEA Schedule
Not Controlled
Overview
What is this medicine?
Magnesium is a natural mineral that your body needs for many important functions, like keeping your muscles and nerves working properly, maintaining a healthy heart rhythm, and building strong bones. Magnesium 200mg tablets are used to supplement your diet if you're not getting enough magnesium, or to help with conditions like constipation or indigestion.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with food and a full glass of water.
Storing and Disposing of Your Medication
Keep your medication at room temperature in a dry place, away from the bathroom. Protect it from heat and light. Store all medications in a safe location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take two doses at the same time or take extra doses.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication with food and a full glass of water.
Storing and Disposing of Your Medication
Keep your medication at room temperature in a dry place, away from the bathroom. Protect it from heat and light. Store all medications in a safe location, out of the reach of children and pets.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and continue with your regular dosing schedule. Do not take two doses at the same time or take extra doses.
Lifestyle & Tips
- Maintain a balanced diet rich in magnesium (e.g., leafy green vegetables, nuts, seeds, whole grains, legumes).
- Avoid excessive alcohol intake, which can deplete magnesium.
- Stay hydrated, especially if using magnesium for laxative effects.
- Inform your healthcare provider about all medications and supplements you are taking, as magnesium can interact with certain drugs.
Available Forms & Alternatives
Available Strengths:
- Magnesium Oxide 400mg Tablets
- Magnesium Sulfate 50% Inj, 10ml
- Magnesium 500mg Tablets
- Magnesium Sulfate 40mg/ml Inj, 50ml
- Magnesium Chloride 20% Inj, 50ml
- Magnesium Sulf 40mg/ml Inj, 100ml
- Magnesium Sulfate 50% Inj, 50ml
- Magnesium 200mg Tablets
- Magnesium Sulfate 50% Inj, 2ml
- Magnesium 300mg Capsules
- Magnesium Sulfate 40mg/ml Inj, 50ml
- Magnesium Sulfate 80mg/ml Inj, 50ml
- Magnesium 250mg Tablets
- Magnesium Sulfate 80mg/ml Inj
- Magn Sulf/d5w 10mg/ml Inj, 100ml
- Magnesium Oxide 250mg Tablets
- Magnesium Citrate Soln Lemon 296ml
- Magnesium Sulfate 50% Inj, 20ml
- Magnesium Su 40g/1000ml Inj, 1000ml
- Magnesium Sulfate 20gm/500ml Inj
Dosing & Administration
Adult Dosing
Standard Dose:
200-400 mg elemental magnesium orally once daily
Dose Range:
200 - 400 mg
Condition-Specific Dosing:
magnesium_deficiency:
200-400 mg elemental magnesium orally once or twice daily, adjusted based on serum levels and tolerance.
constipation:
250-500 mg elemental magnesium (often as magnesium citrate or oxide) orally once daily or as needed, typically at bedtime. Higher doses may be used for bowel preparation.
dyspepsia:
200-400 mg elemental magnesium (often as magnesium hydroxide) orally as needed.
Pediatric Dosing
Neonatal:
Not established for general supplementation; specific medical indications only.
Infant:
Not established for general supplementation; specific medical indications only.
Child:
Dosing varies by age and indication (e.g., 100-200 mg elemental magnesium daily for supplementation, or 40-50 mg/kg/day for constipation, divided). Consult pediatrician.
Adolescent:
Similar to adult dosing for supplementation (200-400 mg elemental magnesium daily), or 250-500 mg for constipation.
Dose Adjustments
Renal Impairment:
Mild:
Use with caution; monitor serum magnesium.
Moderate:
Reduce dose by 50% or avoid; monitor serum magnesium closely.
Severe:
Contraindicated due to risk of hypermagnesemia.
Dialysis:
Contraindicated; magnesium is typically removed by dialysis, but oral supplementation can lead to accumulation between sessions. Avoid unless specifically directed and monitored.
Hepatic Impairment:
Mild:
No specific adjustment needed.
Moderate:
No specific adjustment needed.
Severe:
No specific adjustment needed.
Pharmacology
Mechanism of Action
Magnesium is an essential mineral and electrolyte, acting as a cofactor for over 300 enzymatic reactions, including those involved in ATP production, protein and nucleic acid synthesis, muscle contraction, nerve transmission, and blood glucose control. It stabilizes cell membranes, influences calcium channels, and plays a role in bone structure. As a laxative, magnesium salts exert an osmotic effect in the gut, drawing water into the lumen and stimulating bowel motility. As an antacid, magnesium hydroxide neutralizes gastric acid.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 25-60% (variable, depends on dose, magnesium status, and salt form)
Tmax:
Variable, typically 2-8 hours for oral forms.
FoodEffect:
Food can decrease the rate and extent of absorption, but may reduce gastrointestinal upset.
Distribution:
Vd:
Not precisely defined for oral supplementation; primarily distributed to bone (50-60%), soft tissues (39-49%), and extracellular fluid (1%).
ProteinBinding:
Approximately 25-30% (to albumin and globulins).
CnssPenetration:
Limited under normal conditions; can increase with hypermagnesemia.
Elimination:
HalfLife:
Variable; depends on magnesium status and renal function (e.g., 20-28 hours in healthy individuals, significantly prolonged in renal impairment).
Clearance:
Primarily renal excretion; glomerular filtration with tubular reabsorption.
ExcretionRoute:
Urine (primary for absorbed magnesium), feces (unabsorbed magnesium).
Unchanged:
100% (as magnesium ion).
Pharmacodynamics
OnsetOfAction:
For deficiency: Days to weeks for clinical improvement. For laxative effect: 0.5-6 hours. For antacid effect: Minutes.
PeakEffect:
For deficiency: Weeks. For laxative effect: 1-6 hours. For antacid effect: 30-60 minutes.
DurationOfAction:
For deficiency: Sustained with continued supplementation. For laxative effect: Variable, typically 6-12 hours. For antacid effect: 1-3 hours.
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
If you experience any of the following symptoms, call your doctor immediately or seek emergency medical attention, as they may be signs of a severe and potentially life-threatening reaction:
- Signs of an allergic reaction, such as rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
- Severe stomach upset or vomiting.
Other Possible Side Effects
Like all medications, this drug can cause side effects, although not everyone will experience them. Many people have either no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor for advice:
- Diarrhea.
Important Note
This list does not include all possible side effects. If you have concerns about side effects, consult your doctor. For medical advice regarding side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
If you experience any of the following symptoms, call your doctor immediately or seek emergency medical attention, as they may be signs of a severe and potentially life-threatening reaction:
- Signs of an allergic reaction, such as rash, hives, itching, red, swollen, blistered, or peeling skin (with or without fever), wheezing, tightness in the chest or throat, difficulty breathing, swallowing, or talking, unusual hoarseness, or swelling of the mouth, face, lips, tongue, or throat.
- Severe stomach upset or vomiting.
Other Possible Side Effects
Like all medications, this drug can cause side effects, although not everyone will experience them. Many people have either no side effects or only mild ones. If you are bothered by any of the following side effects or if they do not go away, contact your doctor for advice:
- Diarrhea.
Important Note
This list does not include all possible side effects. If you have concerns about side effects, consult your doctor. For medical advice regarding side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Signs of too much magnesium (hypermagnesemia): severe tiredness, muscle weakness, slow heartbeat, low blood pressure, nausea, vomiting, diarrhea. Seek immediate medical attention.
- Signs of too little magnesium (hypomagnesemia): muscle cramps, tremors, fatigue, numbness or tingling, irregular heartbeat. Consult your doctor.
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor identify potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions or exacerbate underlying health issues.
To ensure your safety, it is crucial to verify that this medication can be taken safely with all your current medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced as a result of the allergy.
All medications you are currently taking, including prescription and over-the-counter (OTC) drugs, natural products, and vitamins. This information will help your doctor identify potential interactions between this medication and other substances.
* Any existing health problems, as this medication may interact with certain conditions or exacerbate underlying health issues.
To ensure your safety, it is crucial to verify that this medication can be taken safely with all your current medications and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all of your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests will be necessary, as directed by your doctor, to monitor your condition. Be sure to discuss any concerns or questions you have with your doctor. If you are pregnant, planning to become pregnant, or are breastfeeding, notify your doctor immediately. You and your doctor will need to carefully weigh the benefits and risks of this medication to both you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
- Abdominal cramping
- Lethargy
- Muscle weakness
- Hypotension (low blood pressure)
- Bradycardia (slow heart rate)
- CNS depression (drowsiness, confusion)
- Respiratory depression (difficulty breathing)
- Coma
- Cardiac arrest
What to Do:
If you suspect an overdose, seek immediate medical attention or call a poison control center (e.g., 1-800-222-1222 in the US). Management may include intravenous calcium gluconate (to counteract cardiac effects), forced diuresis, and in severe cases, hemodialysis.
Drug Interactions
Contraindicated Interactions
- Patients with severe renal impairment (CrCl < 30 mL/min) due to risk of hypermagnesemia.
Major Interactions
- Tetracyclines (e.g., doxycycline, minocycline): Magnesium can chelate these antibiotics, reducing their absorption. Separate administration by at least 2-4 hours.
- Fluoroquinolones (e.g., ciprofloxacin, levofloxacin): Magnesium can chelate these antibiotics, reducing their absorption. Separate administration by at least 2-6 hours.
- Potassium-sparing diuretics (e.g., amiloride, spironolactone, triamterene): May increase risk of hypermagnesemia, especially in renal impairment.
- Neuromuscular blockers (e.g., rocuronium, vecuronium): Magnesium can potentiate their effects, leading to prolonged paralysis and respiratory depression.
Moderate Interactions
- Bisphosphonates (e.g., alendronate, risedronate): Magnesium can interfere with their absorption. Separate administration by at least 30 minutes to 2 hours.
- Levothyroxine: Magnesium can impair absorption. Separate administration by at least 4 hours.
- Digoxin: High magnesium levels can interfere with digoxin's cardiac effects, while hypomagnesemia can increase digoxin toxicity.
- Calcium channel blockers (e.g., amlodipine, nifedipine): Additive hypotensive effects and increased risk of bradycardia.
- Other laxatives: Increased risk of diarrhea and electrolyte imbalance.
Minor Interactions
- Certain iron supplements: May reduce iron absorption if taken concurrently, though less significant than with calcium.
Monitoring
Baseline Monitoring
Serum Magnesium
Rationale: To assess baseline magnesium status, especially if deficiency is suspected or patient has risk factors for imbalance (e.g., renal impairment, GI disorders).
Timing: Prior to initiation of high-dose supplementation or in at-risk patients.
Renal Function (BUN, Creatinine, eGFR)
Rationale: Magnesium is primarily renally excreted; impaired renal function significantly increases risk of hypermagnesemia.
Timing: Prior to initiation, especially in elderly or those with known renal issues.
Routine Monitoring
Serum Magnesium
Frequency: Periodically (e.g., every 1-3 months) for patients on high-dose supplementation or with renal impairment; as needed for symptoms.
Target: 1.7-2.2 mg/dL (0.7-0.9 mmol/L)
Action Threshold: If > 2.5 mg/dL (1.03 mmol/L) or symptoms of hypermagnesemia, reduce dose or discontinue. If < 1.7 mg/dL (0.7 mmol/L) and symptoms, consider dose increase or alternative form.
Symptoms of Hypermagnesemia
Frequency: Daily, especially during initiation or dose changes.
Target: Absence of symptoms
Action Threshold: Muscle weakness, lethargy, nausea, vomiting, diarrhea, hypotension, bradycardia, respiratory depression. Seek medical attention immediately.
Symptoms of Hypomagnesemia
Frequency: Daily, especially if underlying conditions predispose to deficiency.
Target: Absence of symptoms
Action Threshold: Muscle cramps, tremors, fatigue, weakness, numbness, tingling, seizures, cardiac arrhythmias. Seek medical attention.
Bowel Habits (if used for constipation)
Frequency: Daily
Target: Regular, soft bowel movements
Action Threshold: Excessive diarrhea or continued constipation; adjust dose.
Symptom Monitoring
- Muscle weakness
- Lethargy
- Nausea
- Vomiting
- Diarrhea
- Abdominal cramping
- Dizziness
- Headache
- Irregular heartbeat (palpitations)
- Low blood pressure (hypotension)
- Slow heart rate (bradycardia)
- Difficulty breathing (in severe cases of hypermagnesemia)
- Muscle cramps or spasms (hypomagnesemia)
- Tremors (hypomagnesemia)
- Numbness or tingling (hypomagnesemia)
- Seizures (severe hypomagnesemia)
Special Patient Groups
Pregnancy
Magnesium is an essential nutrient during pregnancy. Oral supplementation is generally considered safe and often recommended to meet increased dietary needs. High doses or intravenous magnesium are used for specific medical conditions like pre-eclampsia/eclampsia, but this is distinct from oral supplementation.
Trimester-Specific Risks:
First Trimester:
Generally considered safe and important for fetal development.
Second Trimester:
Generally considered safe.
Third Trimester:
Generally considered safe; IV magnesium is used for pre-eclampsia/eclampsia management.
Lactation
Magnesium is naturally present in breast milk and is considered compatible with breastfeeding. Oral supplementation at recommended doses is generally safe for the nursing infant.
Infant Risk:
Low risk; magnesium is an essential nutrient for infants.
Pediatric Use
Use with caution and under medical supervision. Dosing must be carefully adjusted by age and weight. Risk of hypermagnesemia is higher in infants and young children, especially with renal impairment or excessive doses. Not for routine use as a laxative in infants without medical advice.
Geriatric Use
Elderly patients may have age-related decline in renal function, increasing the risk of hypermagnesemia. Start with lower doses and monitor renal function and serum magnesium levels closely. They may also be more susceptible to the laxative effects and potential dehydration.
Clinical Information
Clinical Pearls
- Magnesium comes in various salt forms (e.g., oxide, citrate, glycinate, malate), which differ in elemental magnesium content and bioavailability. Magnesium oxide has high elemental content but lower bioavailability; magnesium citrate and glycinate are generally better absorbed.
- The 200mg refers to elemental magnesium, which is the active component.
- Common side effects, especially at higher doses, include diarrhea, nausea, and abdominal cramping.
- Always check for drug interactions, particularly with antibiotics (tetracyclines, fluoroquinolones) and bisphosphonates, requiring spaced administration.
- Patients with kidney disease are at high risk for magnesium accumulation and toxicity; magnesium supplementation is often contraindicated in severe renal impairment.
- Symptoms of magnesium deficiency can be subtle and non-specific, including muscle cramps, fatigue, and weakness.
- Magnesium can be beneficial for muscle cramps, restless legs syndrome, migraine prophylaxis, and constipation, but efficacy varies by individual and specific condition.
Alternative Therapies
- For magnesium deficiency: Dietary changes, other magnesium salt forms (e.g., magnesium citrate, glycinate, malate).
- For constipation: Fiber supplements (psyllium, methylcellulose), stool softeners (docusate), osmotic laxatives (polyethylene glycol, lactulose), stimulant laxatives (senna, bisacodyl).
- For dyspepsia/antacid: Calcium carbonate, aluminum hydroxide, H2 blockers (famotidine), proton pump inhibitors (omeprazole).
Cost & Coverage
Average Cost:
$5 - $20 per 30-100 tablets
Generic Available:
Yes
Insurance Coverage:
Generally over-the-counter (OTC) and not covered by most insurance plans unless prescribed for a specific medical condition and a prescription is submitted.
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about your medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.