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Terms Of Use


Brand Name(s) : Phillip's Milk of Magnesia, Maalox (in combination with aluminium hydroxide), Maalox Plus (in combination with simeticone and aluminium hydroxide)
Side Effects


Magnesium hydroxide should be used with caution in: the elderly or weak (debilitated) patients, children under the age of 3 years, and those with liver or kidney problems.

It should not be used in: patients with sudden onset of a gastro-intestinal (stomach or bowel) condition.

Also see list of precautions and interactions.


Store below 25°C. Do not freeze.


What is it used for?

  • Magnesium hydroxide is used to treat a number of problems.
  • It is an antacid (neutralising acidic stomach contents), as well as an osmotic laxative, which induces a laxative effect (stimulating stool production).
  • It is used as an oral suspension to relieve constipation by acting as an osmotic laxative which encourages water to be retained in the gut and faeces, and it is also used as an antacid for the relief of stomach discomfort, indigestion, heartburn (a burning feeling in the chest, behind the breastbone or gullet) and wind (flatulence). Magnesium hydroxide reacts with hydrochloric acid in the stomach to form magnesium chloride which neutralises the acidity of the stomach contents.
  • In general, this drug is used to relieve constipation and for the relief of indigestion.
  • Benefits of being on this drug can include regular bowel movements, and relief from the painful symptoms of indigestion and heartburn.

Listed below are the typical uses of magnesium hydroxide.

  • Relief of constipation
  • Relief of stomach discomfort, indigestion, stomach acidity, heartburn and flatulence.

On occasion your doctor may prescribe this medicine to treat a condition not on the above list. Such conditions are listed below.


How often do I take it?

  • Take this medication orally, as required, and normally at bedtime when used as a laxative.
  • Use this medication regularly in order to get the most benefit from it.
  • Remember to use it at the same time each day - unless specifically told otherwise by your doctor.
  • It may take some time before the full benefit of this drug takes effect.
  • Certain medical conditions may require different dosage instructions as directed by your doctor.

What dose?

  • Dosage is based on your age, gender, medical condition, response to therapy, and use of certain interacting medicines.

Do I need to avoid anything?

  • No. Consult your doctor or pharmacist for more details.

When can I stop?

  • Complete the full course until the symptoms resolve. Speak to your doctor if your symptoms do not go away.


Only the most common side effects have been listed. If any of these persist or you consider them severe then inform your doctor.

Tell your doctor immediately if you develop any of the following symptoms: prolonged constipation.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

A serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

The Yellow Card Scheme allows you to report suspected side effects from any type of medicine (which includes vaccines, herbals and over the counter medicines) that you are taking. It is run by the medicines safety watchdog called the Medicines and Healthcare products Regulatory agency (MHRA). Please report any suspected side effect on the Yellow Card Scheme website.


Before taking magnesium hydroxide, tell your doctor or pharmacist if you are allergic to it; or to other laxatives; or if you have any other allergies.

This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a gastro-intestinal (stomach or bowel) condition of sudden onset.

Before using this medication, tell your doctor or pharmacist your medical history, especially any of the following: any history of bowel disorders, or bloody stools.

Before having surgery, tell your doctor or dentist that you are taking this medication.

Does alcohol intake affect this drug?

  • Alcohol intake is not known to affect magnesium hydroxide.

The elderly: magnesium hydroxide can be used in the elderly.

Pregnancy and breastfeeding - please ensure you read the detailed information below


The safety of magnesium hydroxide has not been established during pregnancy. Ask your doctor or pharmacist if you have any doubts or questions about this.

It is sensible to limit use of medication during pregnancy whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


Magnesium hydroxide should not be used if you are breastfeeding, unless considered necessary by your doctor

It is sensible to limit use of medication during breastfeeding whenever possible. However, your doctor may decide that the benefits outweigh the risks in individual circumstances and after a careful assessment of your specific health situation.

If you have any doubts or concerns you are advised to discuss the medicine with your doctor or pharmacist.


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 them first.

This drug should not be used with the following medications because very serious, possibly fatal interactions may occur: none known

Before using this medication, tell your doctor or pharmacist of all prescription and non-prescription/herbal products you may use, especially of:

This information does not contain all possible interactions. Therefore, before using magnesium hydroxide, tell your doctor or pharmacist of all the products you use.


Symptoms of an overdose may include: watery diarrhoea, and potential magnesium poisoning which can be associated with nausea (feeling sick), vomiting, flushing, thirst, low blood pressure, drowsiness, confusion, loss of tendon reflexes, muscle weakness, slowed breathing (respiratory depression), heartbeat rhythm problems (arrhythmias), coma (unable to wake), and heart attack.

If you think you, or someone you care for, might have accidentally taken more than the recommended dose of bisacodyl or intentional overdose is suspected, contact your local hospital, GP or if in England call 111. In Scotland call NHS 24. In Wales, call NHS Direct Wales. In the case of medical emergencies, always dial 999.


If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

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Source: Selected from data included with permission and copyrighted by Boots UK Limited. This copyrighted material is sourced from a licensed data provider and is not for distribution, except as may be authorised by the applicable terms of use.
CONDITIONS OF USE: The information in this database is intended to supplement, not substitute for, the expertise and judgement of healthcare professionals. The information is not intended to cover all possible uses, directions, precautions, drug interactions or adverse events, nor should it be construed to indicate that use of a particular medicine is safe, appropriate or effective for you or anyone else. A healthcare professional should be consulted before taking any medicine, changing any diet, or discontinuing any course of treatment.

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