Generic Name Magnesium Hydroxide
Bangla Name ম্যাগনেসিয়াম হাইড্রোক্সাইড
Available brands 8
Language

Introduction

Magnesium hydroxide is an inorganic compound. It is naturally found as the mineral brucite. Magnesium hydroxide can be used as an antacid or a laxative in either an oral liquid suspension or chewable tablet form. Additionally, magnesium hydroxide has smoke suppressing and flame retardant properties and is thus used commercially as a fire retardant. It can also be used topically as a deodorant or for the relief of canker sores (aphthous ulcers).

Uses

Magnesium hydroxide is an inorganic compound used as a laxative and antacid.

Magnesium hydroxide can be used as an antacid or a laxative depending on the administered dose.

As an antacid, it is used for the temporary relief of heartburn, upset stomach, sour stomach or acid indigestion.

As a laxative, it is used for the relief of occasional constipation by promoting bowel movements for 30 minutes and up to 6 hours.

Associated Conditions

  • Acid indigestion
  • Colic
  • Constipation
  • Dyspepsia
  • Flatulence
  • Gastric Ulcer
  • Heartburn
  • Upset stomach
  • Antacid therapy
  • Gastric Acid Suppression

Pharmacodynamics

As an antacid, magnesium hydroxide suspension neutralizes gastric acid by reacting with hydrochloric acid in the stomach to form magnesium chloride and water. It is practically insoluble in water and does not have any effect until it reacts with the hydrochloric acid in the stomach. There, it decreases the direct acid irritant effect and increases the pH in the stomach leading to inactivation of pepsin. Magnesium hydroxide enhances the integrity of the mucosal barrier of the stomach as well as improving the tone of both the gastric and esophageal sphincters.

As a laxative, the magnesium hydroxide works by increasing the osmotic effect in the intestinal tract and drawing water in. This creates distension of the colon which results in an increase in peristaltic movement and bowel evacuation.

Mechanism of Action

The suspension of magnesium hydroxide is ingested and enters the stomach. According to the amount ingested, the magnesium hydroxide will either act as an antacid or a laxative.

Through the ingestion of 0.5-1.5 grams (in adults) the magnesium hydroxide will act by simple acid neutralization in the stomach. The hydroxide ions from the magnesium hydroxide suspension will combine with the acidic H+ ions of the hydrochloric acid made by the stomachs parietal cells. This neutralization reaction will result in the formation of magnesium chloride and water.

Through the ingestion of 2-5 grams (in adults) the magnesium hydroxide acts as a laxative in the colon. The majority of the suspension is not absorbed in the intestinal tract and will create an osmotic effect to draw water into the gut from surrounding tissues. With this increase of water in the intestines, the feces will soften and the intraluminal volume of the feces will increase. These effects still stimulate intestinal motility and induce the urge to defecate. Magnesium hydroxide will also release cholecystokinin (CKK) in the intestines which will accumulate water and electrolytes in the lumen and furthermore increase intestinal motility.

Absorption

About 15%-50% of magnesium hydroxide is absorbed very slowly through the small intestine.

Volume of Distribution

The peak action and distribution of magnesium hydroxide are variable.

Protein Binding

Magnesium hydroxide does not have any protein binding properties.

Route of Elimination

After oral administration, up to 50% of the magnesium hydroxide suspension may be absorbed as magnesium ions through the small intestines and then rapidly excreted in the urine through the kidneys. The unabsorbed drug is mainly excreted in the feces and saliva.

Half Life

N/A

Clearance

Magnesium hydroxide is mainly excreted in the urine by the kidneys. Since the kidneys play a major role in its clearance, individuals with renal failure are at risk of hypermagnesemia with long term consumption as the appropriate amounts of magnesium may not be excreted.

Toxicity

LD50=8500 mg/kg (rat, oral)

Common side effects include drowsiness or flushing (warmth, redness or tingly feeling).

Daily use of magnesium hydroxide can result in fluid and electrolyte disturbances.

Excessive use of the laxative effects of magnesium hydroxide may result in abdominal cramping, nausea and/or diarrhea.

In overdose, symptoms of gastrointestinal irritation and/or watery diarrhea may occur.

Magnesium hydroxide poisoning can result in hypermagnesemia which includes symptoms of: nausea, vomiting, flushing, thirst, hypotension, drowsiness, confusion, loss of tendon reflexes, muscle weakness, respiratory depression, cardiac arrhythmias, coma and cardiac arrest.

Not to be used in individuals with any form of kidney disease or renal failure, a magnesium restricted diet or with any sudden changes in bowel movement lasting over two weeks. Also not to be used in those individuals with abdominal pain, nausea, vomiting, symptoms of appendicitis or myocardial damage, heart block, fecal impaction, rectal fissures, intestinal obstruction or perforation or renal disease. Not to be used in women who are about to deliver as magnesium crosses the placenta and is excreted in small amounts in breast milk.

Using magnesium hydroxide with aluminum hydroxide can decrease the absorption rate of these drugs.

Magnesium hydroxide can react with digoxin, dicoumerol and cimetidine.

Use of ibuprofen with magnesium hydroxide can increase the absorption of the ibuprofen.

Use of magnesium hydroxide with penicallamine, bisphosphates, ketoconazole, quinolones or tetracycline can decrease the absorption of these drugs.

Enteric-coated tablets can be prematurely released when taken with magnesium hydroxide.

It is important to routinely monitor levels of serum magnesium and potassium in patients using magnesium hydroxide. Serum magnesium levels are necessary to determine how much magnesium is being absorbed and how much is being excreted by the kidneys. Excessive diarrhea can occur from use of magnesium hydroxide and thus it is important to also monitor serum potassium levels to ensure hypokalemia does not occur.

Food Interactions

No interactions found.

Dosage

As Laxative:
  • Adults: 2-4 Tablespoonful with a full glass of water.
  • Children: 6-11 years: 1-2 Tablespoonful with a full glass of water. 2-5 years: 1-3 Teaspoonful with a full glass of water.
As Antacid:
  • Adults: 1-3 teaspoonful (5 to 15 ml) up to 4 times daily with water.
  • Children: 1-3 years: ¼ teaspoonful. 3-6 years: ¼-½ teaspoonful. 6-12 years: ½-1 teaspoonful

Frequently Asked Questions About Magnesium Hydroxide

1. What is Magnesium Hydroxide?

Magnesium Hydroxide is an inorganic compound commonly used as an antacid and a laxative. It works by neutralizing stomach acid and increasing water in the intestines to ease bowel movements. It is most commonly found in liquid form and tablets for gastrointestinal issues.

2. How does Magnesium Hydroxide work as an antacid?

As an antacid, Magnesium Hydroxide works by neutralizing excess stomach acid. It reacts with hydrochloric acid (HCl) in the stomach to form magnesium chloride, water, and carbon dioxide, which helps relieve heartburn, indigestion, and acid reflux.

3. How does Magnesium Hydroxide function as a laxative?

Magnesium Hydroxide acts as an osmotic laxative by drawing water into the colon, which softens stool and stimulates bowel movements. This helps relieve constipation by increasing the fluid content of stool and making it easier to pass.

4. What are the common uses of Magnesium Hydroxide?

Magnesium Hydroxide is primarily used for:

  • Relieving heartburn and indigestion (antacid)
  • Managing constipation (laxative)
  • Reducing symptoms of acid reflux
  • Treating magnesium deficiency in certain medical conditions

5. What is the recommended dosage of Magnesium Hydroxide for heartburn?

The usual adult dosage for heartburn or indigestion is 5 to 15 mL of Magnesium Hydroxide suspension taken once or twice daily, depending on the severity of the symptoms. It’s important to follow your healthcare provider’s recommendations for dosage.

6. What is the recommended dosage of Magnesium Hydroxide for constipation?

For constipation, the recommended dose for adults is typically 30 to 60 mL of the liquid form once daily. For children, the dosage should be reduced based on age and weight, and you should consult a pediatrician before use.

7. Can Magnesium Hydroxide be used during pregnancy?

Magnesium Hydroxide is generally considered safe during pregnancy when used as directed. However, it should be used under the guidance of a healthcare provider to avoid excessive magnesium intake, which could lead to complications.

8. Can Magnesium Hydroxide be used for children?

Magnesium Hydroxide can be used for children to treat constipation, but the dosage should be carefully controlled based on the child's age and weight. Always consult a pediatrician before using any medication for children.

9. Are there any side effects of Magnesium Hydroxide?

Common side effects of Magnesium Hydroxide include:

  • Diarrhea
  • Stomach cramps
  • Gas or bloating
In rare cases, high doses or prolonged use can lead to magnesium toxicity, which can cause symptoms like low blood pressure, slow heartbeat, and breathing problems.

10. Can Magnesium Hydroxide cause dehydration?

Yes, Magnesium Hydroxide can cause dehydration, especially if it leads to excessive diarrhea. It's important to stay hydrated and consult a healthcare provider if symptoms persist.

11. Can Magnesium Hydroxide interact with other medications?

Magnesium Hydroxide can interact with certain medications, including:

  • Antibiotics (e.g., tetracyclines, fluoroquinolones)
  • Blood pressure medications
  • Diuretics
Always inform your doctor about all medications you are taking before using Magnesium Hydroxide.

12. What happens if I take too much Magnesium Hydroxide?

Taking too much Magnesium Hydroxide can lead to magnesium toxicity, which may cause symptoms such as:

  • Low blood pressure
  • Slow heart rate
  • Difficulty breathing
  • Confusion
  • Loss of consciousness
If an overdose is suspected, seek immediate medical attention.

13. Can Magnesium Hydroxide be used for acid reflux?

Magnesium Hydroxide can help relieve acid reflux by neutralizing stomach acid. However, it may not be as effective as other medications like proton pump inhibitors or H2 blockers for long-term acid reflux management.

14. Is Magnesium Hydroxide safe for long-term use?

Magnesium Hydroxide is not recommended for long-term use, particularly as a laxative, as it may lead to electrolyte imbalances or dependence. It's best used for short-term relief unless otherwise instructed by a healthcare provider.

15. How should Magnesium Hydroxide be stored?

Magnesium Hydroxide should be stored at room temperature, away from moisture and direct sunlight. It should be kept tightly closed in its original container to avoid contamination.

16. Can Magnesium Hydroxide be used for kidney patients?

Patients with kidney disease should use Magnesium Hydroxide with caution, as impaired kidney function may affect magnesium clearance from the body, leading to magnesium toxicity. A healthcare provider should be consulted for appropriate dosing.

17. How fast does Magnesium Hydroxide work as a laxative?

Magnesium Hydroxide typically works within 30 minutes to 6 hours after ingestion, depending on the individual and their specific condition.

18. Can I drink alcohol while taking Magnesium Hydroxide?

It is not recommended to drink alcohol while taking Magnesium Hydroxide as it can worsen side effects like dizziness, drowsiness, or dehydration.

19. Can Magnesium Hydroxide cause gas or bloating?

Yes, Magnesium Hydroxide can cause gas or bloating as a side effect, especially if it causes diarrhea. These symptoms typically resolve once your body adjusts to the medication.

20. Can Magnesium Hydroxide be used for heartburn relief in children?

Magnesium Hydroxide can be used for heartburn relief in children, but the dosage must be adjusted according to age and weight. Always consult a pediatrician before administering it to a child.

21. Is Magnesium Hydroxide the same as Milk of Magnesia?

Yes, Milk of Magnesia is a common brand name for Magnesium Hydroxide. It is available in liquid form and is used primarily as an antacid and laxative.

22. Can Magnesium Hydroxide help with acid indigestion?

Magnesium Hydroxide can relieve acid indigestion by neutralizing excess stomach acid and reducing the discomfort associated with acid buildup in the stomach.

23. Is Magnesium Hydroxide effective for morning sickness during pregnancy?

Magnesium Hydroxide may help with acid reflux or heartburn symptoms that can accompany morning sickness, but it is important to consult a healthcare provider before using it during pregnancy.

24. Can I take Magnesium Hydroxide with food?

Magnesium Hydroxide can be taken with or without food. However, taking it after meals may help alleviate discomfort caused by indigestion or acid reflux.

25. How does Magnesium Hydroxide compare to other antacids?

Magnesium Hydroxide is often preferred for people who have trouble with other antacids like calcium carbonate, as it does not cause constipation. However, it can cause diarrhea, which other antacids may not.

26. Can Magnesium Hydroxide be used for nausea?

Magnesium Hydroxide is not typically used for nausea unless it is caused by indigestion or an upset stomach. It is more commonly used for heartburn or constipation-related issues.

27. Can Magnesium Hydroxide be used as a preventive for constipation?

Magnesium Hydroxide may help prevent constipation if used occasionally, but it is not meant for long-term use as a preventive. It's more commonly used for short-term relief of constipation.

28. Can Magnesium Hydroxide be taken with other laxatives?

It is best to avoid using multiple laxatives simultaneously unless directed by a healthcare provider. Combining laxatives can increase the risk of dehydration or electrolyte imbalances.

29. Does Magnesium Hydroxide interact with foods or drinks?

Magnesium Hydroxide does not have significant interactions with foods or drinks, but it is advised to avoid taking it with dairy products, as calcium can interfere with magnesium absorption.

30. Can Magnesium Hydroxide be used for treating ulcers?

Magnesium Hydroxide can provide relief for symptoms of ulcers by neutralizing stomach acid. However, it does not treat the underlying cause of ulcers and should be used in combination with other treatments as prescribed by a doctor.

31. Can Magnesium Hydroxide cause an electrolyte imbalance?

Excessive use of Magnesium Hydroxide can lead to an electrolyte imbalance, especially elevated magnesium levels in the blood. This can cause symptoms such as weakness, confusion, and abnormal heart rhythms.

32. Can Magnesium Hydroxide help with bloating?

Magnesium Hydroxide can help reduce bloating by promoting bowel movements and relieving constipation, which often causes bloating and discomfort.

33. Can Magnesium Hydroxide be used in patients with a history of heart disease?

Magnesium Hydroxide should be used cautiously in patients with heart disease, particularly if they have kidney issues. It is important to consult with a doctor before use to avoid complications related to magnesium levels.

34. Is Magnesium Hydroxide safe for long-term constipation treatment?

Magnesium Hydroxide is not typically recommended for long-term constipation treatment, as prolonged use can lead to dependency and electrolyte disturbances. It is best for short-term use or as part of a broader treatment plan for chronic constipation.

35. Can Magnesium Hydroxide help with gas?

Magnesium Hydroxide may help reduce gas by relieving constipation, which is often a primary cause of bloating and gas buildup. However, it is not a primary treatment for excess gas.

36. Can I stop taking Magnesium Hydroxide suddenly?

It is typically safe to stop taking Magnesium Hydroxide suddenly for short-term use. However, if you have been using it for an extended period or for constipation management, it is advisable to consult a doctor for guidance on discontinuing its use.

37. Can Magnesium Hydroxide be used for nausea caused by chemotherapy?

Magnesium Hydroxide is not specifically used to treat nausea caused by chemotherapy. Anti-nausea medications prescribed by a healthcare provider are typically more effective for chemotherapy-induced nausea.

38. Can Magnesium Hydroxide help with stomach ulcers?

Magnesium Hydroxide can provide temporary relief from the discomfort of stomach ulcers by neutralizing stomach acid. However, it does not heal ulcers and should be used in conjunction with ulcer treatment prescribed by a doctor.

39. Can Magnesium Hydroxide be used for acid indigestion after meals?

Yes, Magnesium Hydroxide can be used to treat acid indigestion after meals by neutralizing the excess acid in the stomach, which can alleviate discomfort.

40. What precautions should I take when using Magnesium Hydroxide?

Precautions include:

  • Consulting a doctor before use if you have kidney problems, heart disease, or are pregnant.
  • Avoiding prolonged use to prevent dependency or electrolyte imbalances.
  • Not exceeding the recommended dose to avoid toxicity.

41. Can Magnesium Hydroxide help with heartburn caused by spicy foods?

Yes, Magnesium Hydroxide can help relieve heartburn caused by spicy foods by neutralizing stomach acid. It can provide quick relief from discomfort.

42. Can I drink water after taking Magnesium Hydroxide?

Yes, drinking water after taking Magnesium Hydroxide can help hydrate your body, especially if the medication causes diarrhea.

43. How does Magnesium Hydroxide compare to other laxatives like Senna?

Magnesium Hydroxide works as an osmotic laxative, drawing water into the intestines to soften stool. Senna, on the other hand, works as a stimulant laxative, stimulating the muscles of the intestines to promote bowel movements. Magnesium Hydroxide is often preferred for gentler action, while Senna can cause more cramping.

44. Can Magnesium Hydroxide cause kidney damage?

Excessive or prolonged use of Magnesium Hydroxide can potentially cause kidney damage, especially in individuals with pre-existing kidney problems. It's crucial to monitor magnesium levels if you have kidney disease.

45. Can Magnesium Hydroxide cause low blood pressure?

Magnesium Hydroxide may cause a drop in blood pressure, particularly if taken in high doses. People with low blood pressure or those on blood pressure medication should use it cautiously and under medical supervision.

46. Can Magnesium Hydroxide be used for abdominal pain?

Magnesium Hydroxide may help relieve abdominal pain if it is caused by constipation or acid reflux. However, it is not a treatment for other types of abdominal pain, such as that caused by infections or ulcers.

47. Does Magnesium Hydroxide interact with food or beverages?

Magnesium Hydroxide does not have major interactions with food or beverages. However, it is best to avoid dairy products, as calcium can interfere with magnesium absorption.

48. Can Magnesium Hydroxide help with stress-related digestion problems?

Magnesium Hydroxide can help relieve indigestion or acid reflux caused by stress. However, it does not address the underlying stress, which should be managed through relaxation techniques or stress reduction strategies.

49. Can Magnesium Hydroxide be used as a digestive aid?

Yes, Magnesium Hydroxide can act as a digestive aid, helping relieve indigestion, heartburn, and constipation. It is particularly useful in alleviating symptoms of acid buildup in the stomach and promoting regular bowel movements.

50. Can I take Magnesium Hydroxide daily?

Magnesium Hydroxide should generally not be taken daily for long periods without consulting a healthcare provider, as it can lead to electrolyte imbalances and dependency for bowel function. It is best used for short-term relief or as part of a doctor's prescribed treatment plan.

Medical review

Last reviewed: 24 Jul 2026

Medically reviewed by:

This is general information, not personal medical advice. Consult a doctor before taking any medicine.

Taking medicines without doctor's advice can cause long-term problems.
Brand medicines containing Magnesium Hydroxide