Magnesium Hydroxide: Side Effects, Uses, Dosage, Interactions, Warnings (2024)

• Uses
  • What Is Magnesium Hydroxide Used For and How Does it Work?
• Dosages
  • Dosages of Magnesium Hydroxide
• Side Effects
  • What Are Side Effects Associated with Using Magnesium Hydroxide?
• Drug Interactions
  • What Other Drugs Interact with Magnesium Hydroxide?
• Warnings and Precautions
  • What Are Warnings and Precautions for Magnesium Hydroxide?

What Is Magnesium Hydroxide Used For and How Does it Work?

Magnesium hydroxide is used to treat constipation and acid indigestion. Magnesium hydroxide is available over-the-counter (OTC) and as a generic.

Magnesium Hydroxide is available under the following different brand names: Milk of Magnesia.

Dosages of Magnesium Hydroxide

Adult and pediatric:

Chewable tablet

• 311 mg
• 400 mg

Suspension

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

Dosage Considerations – Should be Given as Follows:

Constipation in Adults:

• Magnesium hydroxide (400 mg/5 mL): 30-60 mL/day orally at bedtime or in divided doses
• Magnesium hydroxide (800 mg/5 mL): 15-30 mL/day orally at bedtime or in divided doses
• Chewable tablet: 8 tablets/day orally at bedtime or in divided doses

Acid Indigestion in Adults:

• Magnesium hydroxide (400 mg/5 mL): 5-15 mL orally every 4 hours; no more than 4 doses per 24-hour period
• Chewable tablet: 2-4 tablets orally every 4 hours; no more than 4 doses per 24-hour period

Constipation in children:

Suspension

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

Chewable tablet

• Under 3 years: Not recommended
• 3-6 years: 2 tablets orally once daily or in divided doses
• 6-12 years: 4 tablets orally once daily or in divided doses
• 12 years and older: 8 tablets orally once daily or in divided doses

Acid Indigestion in children:

Liquid

• Under 12 years: Not recommended
• 12 years and older: 5-15 mL (400 mg/5 mL) orally every 4 hours; no more than 4 doses per 24-hour period

Chewable tablet

• Under 12 years: Not recommended
• 12 years and older: 2-4 tablets orally every 4 hours; no more than 4 doses per 24-hour period

Children under 2 years: Safety and efficacy not established.

What Are Side Effects Associated with Using Magnesium Hydroxide?

Side effects of magnesium hydroxide include:

• Abdominal cramping
• Diarrhea
• Electrolyte imbalance
• Low blood pressure (hypotension)
• Muscle weakness
• Respiratory depression

This document does not contain all possible side effects and others may occur. Check with your physician for additional information about side effects.

What Other Drugs Interact with Magnesium Hydroxide?

If your doctor has directed you to use this medication, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first.

Serious interactions of magnesium hydroxide include:

• baloxavir marboxil
• demeclocycline
• doxycycline
• eltrombopag
• minocycline
• oxytetracycline
• pazopanib
• ponatinib
• potassium phosphates, IV
• raltegravir
• tetracycline

Moderate interactions of magnesium hydroxide include:

• bictegravir
• ciprofloxacin
• crizotinib
• deferiprone
• deflazacort
• dolutegravir
• fleroxacin
• gemifloxacin
• lanthanum carbonate
• levofloxacin
• moxifloxacin
• ofloxacin
• omadacycline
• pancrelipase
• penicillamine
• pexidartinib
• riociguat
• sarecycline
• sodium phosphates, IV
• vismodegib
• vitamin D

Magnesium Hydroxide has mild interactions with at least 42 different drugs.

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist. Check with your physician if you have health questions or concerns.

What Are Warnings and Precautions for Magnesium Hydroxide?

Warnings

This medication contains magnesium hydroxide. Do not take Milk of Magnesia if you are allergic to magnesium hydroxide or any ingredients contained in this drug.

Keep out of reach of children. In case of overdose, get medical help or contact a Poison Control Center immediately.

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

Effects of Drug Abuse

No information available.

Short-Term Effects

• See "What Are Side Effects Associated with Using Magnesium Hydroxide?"

Long-Term Effects

• See "What Are Side Effects Associated with Using Magnesium Hydroxide?"

Cautions

Use with caution in renal insufficienc.y

Pregnancy and Lactation

Magnesium hydroxide is generally acceptable for use during pregnancy. Controlled studies in pregnant women show no evidence of fetal risk. Use in nursing mothers appears to be safe.