magnesium hydroxide (OTC)

Brand and Other Names:Milk of Magnesia
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Dosing & Uses

AdultPediatric

Dosage Forms & Strengths

chewable tablet

  • 311mg
  • 400mg

suspension

  • 7.75%
  • 400mg/5mL
  • 800mg/5mL
  • 1200mg/15mL
  • 2400mg/10mL

Constipation

Magnesium hydroxide (400 mg/5 mL): 30-60 mL/day PO at bedtime or in divided doses

Magnesium hydroxide (800 mg/5 mL): 15-30 mL/day PO at bedtime or in divided doses

Chewable tablet: 8 tablets/day PO at bedtime or in divided doses

Acid Indigestion

Magnesium hydroxide (400 mg/5 mL): 5-15 mL PO q4hr; no more than 4 doses per 24-hour period

Chewable tablet: 2-4 tablets PO q4hr; no more than 4 doses per 24-hour period

Dosage Forms & Strengths

chewable tablet

  • 311mg
  • 400mg

suspension

  • 7.75%
  • 400mg/5mL
  • 800mg/5mL
  • 1200mg/15mL
  • 2400mg/10mL

Constipation

<2 years: Safety and efficacy not established

Suspension

  • 2-6 years: 5-15 mL/day of regular-strength liquid PO at bedtime or in divided doses
  • 6-12 years: 15-30 mL/day (400 mg/5 mL) or 7.5-15 mL/day (800 mg/5 mL) PO at bedtime or in divided doses
  • ≥12 years: 30-60 mL/day (400 mg/5 mL) or 15-30 mL/day (800 mg/5 mL) PO at bedtime or in divided doses

Chewable tablet

  • <3 years: Not recommended
  • 3-6 years: 2 tablets PO once daily or in divided doses
  • 6-12 years: 4 tablets PO once daily or in divided doses
  • >12 years: 8 tablets PO once daily or in divided doses

Acid Indigestion

Liquid

  • <12 years: Not recommended
  • ≥12 years: 5-15 mL (400 mg/5 mL) PO q4hr; no more than 4 doses per 24-hour period

Chewable tablet

  • <12 years: Not recommended
  • ≥12 years: 2-4 tablets PO q4hr; no more than 4 doses per 24-hour period
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Interactions

Interaction Checker

and magnesium hydroxide

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      Serious - Use Alternative

        Significant - Monitor Closely

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            Contraindicated (0)

              Serious - Use Alternative (13)

              • baloxavir marboxil

                magnesium hydroxide will decrease the level or effect of baloxavir marboxil by cation binding in GI tract. Avoid or Use Alternate Drug. Baloxavir may bind to polyvalent cations resulting in decreased absorption. Studies in monkeys showed concurrent use with calcium, aluminum, or iron caused significantly decreased plasma levels. Human studies not conducted.

              • demeclocycline

                magnesium hydroxide decreases levels of demeclocycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • doxycycline

                magnesium hydroxide decreases levels of doxycycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • eltrombopag

                magnesium hydroxide decreases levels of eltrombopag by inhibition of GI absorption. Applies only to oral form of both agents. Contraindicated. Separate by at least 4 hours.

              • infigratinib

                magnesium hydroxide will decrease the level or effect of infigratinib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer infigratinib 2 hr before and after administration of a locally-acting antacid.

              • minocycline

                magnesium hydroxide decreases levels of minocycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • oxytetracycline

                magnesium hydroxide decreases levels of oxytetracycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • pazopanib

                magnesium hydroxide will decrease the level or effect of pazopanib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug. Avoid coadministration of pazopanib with drugs that raise gastric pH; may use short-acting antacids in place of PPIs and H2 antagonists, but separate antacid and pazopanib dosing by several hours

              • ponatinib

                magnesium hydroxide decreases levels of ponatinib by increasing gastric pH. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              • potassium phosphates, IV

                magnesium hydroxide decreases effects of potassium phosphates, IV by cation binding in GI tract. Avoid or Use Alternate Drug. Magnesium decreases serum phosphate concentration by binding dietary phosphate. Use alternatives if available.

              • raltegravir

                magnesium hydroxide will decrease the level or effect of raltegravir by cation binding in GI tract. Avoid or Use Alternate Drug. Magnesium containing antacids reduce raltegravir plasma levels when taken within 6 hr of raltegravir dose

              • sotorasib

                magnesium hydroxide will decrease the level or effect of sotorasib by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug. If use with an acid-reducing agent cannot be avoided, administer sotorasib 4 hr before or 10 hr after administration of a locally-acting antacid.

              • tetracycline

                magnesium hydroxide decreases levels of tetracycline by inhibition of GI absorption. Applies only to oral form of both agents. Avoid or Use Alternate Drug.

              Monitor Closely (23)

              • bictegravir

                magnesium hydroxide will decrease the level or effect of bictegravir by cation binding in GI tract. Modify Therapy/Monitor Closely. Bictegravir can be taken under fasting conditions 2 hr before antacids containing Al, Mg, or Ca. Routine administration of bictegravir simultaneously with, or 2 hr after, antacids containing Al, Mg, or Ca is not recommended.

              • cabotegravir

                magnesium hydroxide will decrease the level or effect of cabotegravir by cation binding in GI tract. Modify Therapy/Monitor Closely. Administer antacid products at least 2 hr before or 4 hr after taking oral cabotegravir.

              • chloroquine

                magnesium hydroxide will decrease the level or effect of chloroquine by Mechanism: inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Separate doses by at least 4 hr

              • ciprofloxacin

                magnesium hydroxide decreases levels of ciprofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Coadministration of ciprofloxacin with multivalent cation-containing products may reduce the bioavailability of ciprofloxacin by 90%. Administer ciprofloxacin at least 2 hours before or 6 hours after using these products. Use alternatives if available.

              • crizotinib

                magnesium hydroxide decreases levels of crizotinib by increasing gastric pH. Applies only to oral form of both agents. Use Caution/Monitor. Drugs that elevate the gastric pH may decrease the solubility of crizotinib and subsequently reduce its bioavailability. However, no formal studies have been conducted. .

              • deferiprone

                magnesium hydroxide decreases levels of deferiprone by enhancing GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Deferiprone may bind polyvalent cations (eg, iron, aluminum, and zinc), separate administration by at least 4 hr between deferiprone and other medications (eg, antacids), or supplements containing these polyvalent cations.

              • deflazacort

                magnesium hydroxide and deflazacort both decrease serum potassium. Use Caution/Monitor.

              • dolutegravir

                magnesium hydroxide will decrease the level or effect of dolutegravir by cation binding in GI tract. Use Caution/Monitor. Administer dolutegravir 2 hr before or 6 hr after taking medications containing polyvalent cations; use alternative therapy if available

              • fleroxacin

                magnesium hydroxide decreases levels of fleroxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • gemifloxacin

                magnesium hydroxide decreases levels of gemifloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • lanthanum carbonate

                lanthanum carbonate, magnesium hydroxide. cation binding in GI tract. Use Caution/Monitor. Administer antacid at least 2 hours before or after lanthanum. .

              • levofloxacin

                magnesium hydroxide decreases levels of levofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • moxifloxacin

                magnesium hydroxide decreases levels of moxifloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • ofloxacin

                magnesium hydroxide decreases levels of ofloxacin by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • omadacycline

                magnesium hydroxide will decrease the level or effect of omadacycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Multivalent cation-containing products may impair absorption of tetracyclines, which may decrease its efficacy. Separate dosing of tetracyclines from these products.

              • pancrelipase

                magnesium hydroxide decreases effects of pancrelipase by pharmacodynamic antagonism. Use Caution/Monitor. Antacids may negate beneficial effects of enzymes.

              • penicillamine

                magnesium hydroxide decreases levels of penicillamine by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate by 2 hours.

              • pexidartinib

                magnesium hydroxide will decrease the level or effect of pexidartinib by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Separate pexidartinib by 2 hr before or after taking a locally-acting antacid.

              • riociguat

                magnesium hydroxide decreases levels of riociguat by inhibition of GI absorption. Applies only to oral form of both agents. Use Caution/Monitor. Separate administration by at least 1 hour.

              • sarecycline

                magnesium hydroxide will decrease the level or effect of sarecycline by inhibition of GI absorption. Applies only to oral form of both agents. Modify Therapy/Monitor Closely. Multivalent cation-containing products may impair absorption of tetracyclines, which may decrease its efficacy. Separate dosing of tetracyclines from these products.

              • sodium phosphates, IV

                magnesium hydroxide decreases effects of sodium phosphates, IV by cation binding in GI tract. Modify Therapy/Monitor Closely. Magnesium decreases serum phosphate concentration by binding dietary phosphate. Use alternatives if available.

              • vismodegib

                magnesium hydroxide will decrease the level or effect of vismodegib by Other (see comment). Use Caution/Monitor. Drugs that increase gastric pH alter vismodegib solubility and therefore reduce bioavailability; effect on efficacy unknown

              • vitamin D

                vitamin D increases levels of magnesium hydroxide by Other (see comment). Use Caution/Monitor. Comment: Vitamin D can increase serum magnesium concentrations, particularly in the presence of renal impairment. The combined use of vitamin D and magnesium-containing products should be avoided, if possible, in patients with chronic renal failure.

              Minor (41)

              • amikacin

                amikacin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • amiloride

                amiloride increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

              • amphotericin B deoxycholate

                amphotericin B deoxycholate decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • bazedoxifene/conjugated estrogens

                bazedoxifene/conjugated estrogens decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • bendroflumethiazide

                bendroflumethiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • bumetanide

                bumetanide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • calcitonin salmon

                calcitonin salmon increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

              • chlorothiazide

                chlorothiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • chlorthalidone

                chlorthalidone decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • conjugated estrogens

                conjugated estrogens decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • conjugated estrogens, vaginal

                conjugated estrogens, vaginal decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • cyclopenthiazide

                cyclopenthiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • dextrose

                dextrose decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • dextrose (Antidote)

                dextrose (Antidote) decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • digoxin

                digoxin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • doxercalciferol

                doxercalciferol increases levels of magnesium hydroxide by enhancing GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • drospirenone

                drospirenone increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

              • estradiol

                estradiol decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estrogens conjugated synthetic

                estrogens conjugated synthetic decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estrogens esterified

                estrogens esterified decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • estropipate

                estropipate decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • ethacrynic acid

                ethacrynic acid decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • furosemide

                furosemide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • gentamicin

                gentamicin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • glucagon intranasal

                glucagon intranasal increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

              • hydrochlorothiazide

                hydrochlorothiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • ibandronate

                magnesium hydroxide decreases levels of ibandronate by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • indapamide

                indapamide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • mannitol

                mannitol decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • mestranol

                mestranol decreases levels of magnesium hydroxide by Other (see comment). Minor/Significance Unknown. Comment: Magnesium shifted from blood to tissue storage.

              • methyclothiazide

                methyclothiazide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • metolazone

                metolazone decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • neomycin PO

                neomycin PO decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • nitrofurantoin

                magnesium hydroxide decreases levels of nitrofurantoin by inhibition of GI absorption. Applies only to oral form of both agents. Minor/Significance Unknown.

              • paromomycin

                paromomycin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • sodium polystyrene sulfonate

                sodium polystyrene sulfonate increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown. Risk of alkalosis.

              • spironolactone

                spironolactone increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

              • streptomycin

                streptomycin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • tobramycin

                tobramycin decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • torsemide

                torsemide decreases levels of magnesium hydroxide by increasing renal clearance. Minor/Significance Unknown.

              • triamterene

                triamterene increases levels of magnesium hydroxide by decreasing renal clearance. Minor/Significance Unknown.

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              Adverse Effects

              Frequency Not Defined

              Abdominal cramping

              Diarrhea

              Electrolyte imbalance

              Hypotension

              Muscle weakness

              Respiratory depression

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              Warnings

              Contraindications

              Renal failure

              Existing electrolyte imbalance

              Appendicitis symptoms or acute surgical abdomen

              Myocardial damage or heart block

              Fecal impaction or rectal fissures

              Intestinal obstruction or perforation

              Undiagnosed abdominal pain

              Cautions

              Use with caution in renal insufficiency

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              Pregnancy & Lactation

              Pregnancy category: A

              Lactation: Use in nursing mothers appears to be safe

              Pregnancy Categories

              A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.

              B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.

              C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.

              D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.

              X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.

              NA: Information not available.

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              Pharmacology

              Mechanism of Action

              Laxative: Promotes osmotic retention of fluid, which distends the colon with increased peristaltic activity and stimulates bowel evacuation

              Antacid: Reacts with hydrochloric acid in stomach to form magnesium chloride

              Absorption

              Bioavailability: 15-30%

              Onset: 0.5-6 hr (laxative)

              Elimination

              Excretion: Urine (up to 30% as absorbed magnesium), feces (as unabsorbed drug)

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              Images

              BRAND FORM. UNIT PRICE PILL IMAGE
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              311 mg chewable tablet
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Phillips Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk of Magnesia oral
              -
              400 mg/5 mL suspension
              Milk Of Magnesia Concentrated oral
              -
              2,400 mg/10 mL suspension
              Milk Of Magnesia Concentrated oral
              -
              2,400 mg/10 mL suspension
              Pedia-Lax oral
              -
              400 mg (170 mg magnesium) chewable tablet

              Copyright © 2010 First DataBank, Inc.

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              Medscape prescription drug monographs are based on FDA-approved labeling information, unless otherwise noted, combined with additional data derived from primary medical literature.