You've heard of milk of magnesia, which is just another name for magnesium hydroxide. This common medicine can be found in many homes worldwide. Magnesium hydroxide has two primary uses in healthcare - it helps with constipation & reduces stomach acid. To get safe and effective relief, you need to know how to use it and be aware of its side effects. This article explains what this medicine is, its uses, precautions and how to use it.

How Does Magnesium Hydroxide Work?

Magnesium hydroxide's effectiveness comes from its simple chemical properties. It works as an antacid by neutralising stomach acid. The compound reacts with hydrochloric acid to create water and magnesium chloride. This reaction reduces acid irritation and increases stomach pH. The process deactivates pepsin and makes the mucosal barrier stronger.

The compound relieves constipation by pulling water into the intestines through osmosis. Extra fluid makes stools softer and increases intestinal volume. This naturally triggers muscle contractions that move waste through the digestive tract. The magnesium ions also cause digestive hormones to release, which boost bowel movements.

Uses of Magnesium Hydroxide

This versatile compound treats two main conditions. It works as an antacid to give quick relief from heartburn, upset stomach, indigestion and acid reflux. Adults typically need 0.5-1.5 grams as an antacid dose.

The compound helps with occasional constipation as a laxative. Results usually appear between 30 minutes to 6 hours after taking it. Adults usually need 2-5 grams for the laxative effect.

How & When to Take Magnesium Hydroxide?

Follow the product label instructions carefully. Adults dealing with constipation usually take 30-45 ml (six to nine 5 ml spoonfuls). Children between 3-12 years should only take 5-10 ml (one or two 5 ml spoonfuls) with professional guidance.

Take each dose with a full glass of water or milk, ideally at bedtime. The liquid helps the medicine work better. Those using it as an antacid should take it after meals as needed.

What Are the Side Effects of Magnesium Hydroxide?

Side effects are usually mild and don't last long:

• Diarrhoea 

• Stomach cramps (most common)

• Nausea and queasiness

• Bloating and gas

• Mild drowsiness

Serious side effects include:

• Severe diarrhoea

• Confusion

• Muscle weakness

• Irregular heartbeat

• Breathing problems

Can I Take Magnesium Hydroxide Daily?

This medicine works best for occasional use. Never take it more than three days in a row. Long-term use can affect your electrolyte balance.

Simple lifestyle habits changes often work better than taking laxatives for constipation: 

• Drink plenty of water (at least 2 litres daily)

• Eat foods rich in fibre

• Stay physically active

• Avoid eating junk food

These eco-friendly approaches are a great way to get lasting relief compared to medicines alone.

What Precautions Are to Be Taken While Using Magnesium Hydroxide?

These precautions will help you avoid unwanted complications:

• Don't use this medicine if you have kidney disease, intestinal bleeding, or bowel obstruction

• Talk to your doctor before use if you're pregnant, breastfeeding, or giving it to children under 6

• Stop taking it if you get severe cramping, diarrhoea lasting more than 2 days, or rectal bleeding

• Take other medications at least 2 hours apart to prevent reduced absorption

• Watch out for magnesium toxicity signs like muscle weakness, drowsiness, or confusion

You should get medical advice first if you have heart conditions or follow salt-restricted diets. Magnesium compounds can affect your heart rhythm and fluid balance.

What If I Missed a Dose?

You can take magnesium hydroxide as needed for occasional constipation—there's no fixed schedule. If you use it as an antacid and miss a dose, take it when you remember unless it's almost time for your next dose. Never take extra doses to make up for missed ones.

What If I Overdose?

Taking too much magnesium hydroxide can cause serious health problems. Watch for these symptoms:

• Severe diarrhoea

• Extreme thirst

• Muscle weakness

• Irregular heartbeat

• Breathing difficulties

Get medical help right away if you notice these symptoms. Severe magnesium toxicity might need hospital treatment.

Drug Interactions

Magnesium hydroxide affects how your body absorbs many medications. Wait at least two hours before or after taking:

• Antibiotics (especially tetracyclines and quinolones)

• Iron supplements

• Blood thinners

• Bisphosphonates for osteoporosis

• Heart medications

• Anti-seizure drugs

• Thyroid medicines

This medicine can boost the effects of certain muscle relaxants and make digitalis medication's side effects worse.

Dosage for Magnesium Hydroxide

For adults:

• Laxative: 30-60 ml once daily, best taken at bedtime

• Antacid: 5-15 ml up to four times daily between meals

For children (6-12 years):

• Laxative: 15-30 ml once daily

• Antacid: 2.5-7.5 ml up to four times daily

Make sure to drink a full glass of water with each dose.

Magnesium Hydroxide vs Aluminium Hydroxide 

Characteristic	Magnesium Hydroxide	Aluminium Hydroxide
Primary effect	Laxative and antacid	Antacid only
Action speed	Rapid relief	Slower but longer-lasting
Side effects	May cause diarrhoea	May cause constipation
Formula	Mg(OH)₂	Al(OH)₃
Common names	Milk of Magnesia	Amphojel
Best for	Short-term constipation	Long-term acid control
Interactions	Many drug interactions	Fewer drug interactions

FAQs

1. What is Magnesium Hydroxide used for?

   This compound plays two important roles in healthcare:

   • It acts as an antacid to neutralise stomach acid and provides relief from heartburn, indigestion, and upset stomach

   • It works as a laxative and treats occasional constipation by pulling water into the bowels

   • It helps with hyperacidity and bloating

   People often take it to clean their bowels before medical procedures like colonoscopies.

2. How fast does Magnesium Hydroxide work for constipation?

   Results usually come quickly. You can expect a bowel movement between 30 minutes to 6 hours after taking it. This quick action makes it perfect for people who need fast relief, though everyone responds differently. Many people take it before bed to have a morning bowel movement.

3. Can I take Magnesium Hydroxide daily?

   The short answer is no. Doctors recommend against using magnesium hydroxide for more than 7 days straight without medical advice. Your body might become dependent on laxatives. Long-term use can throw off your electrolyte balance and make digestive problems worse.

4. Are there any side effects of using Magnesium Hydroxide regularly?

   While many people tolerate it well, regular use can cause several side effects:

   • Diarrhoea 

   • Stomach cramps 

   • Nausea & vomiting

   • Bloating and gas

   You need immediate medical help if you experience severe diarrhoea, rectal bleeding, confusion, muscle weakness, or irregular heartbeat.

5. What's the difference between Magnesium Hydroxide and Milk of Magnesia?

   They're exactly the same thing. Milk of Magnesia is just a brand name for magnesium hydroxide. Charles Henry Phillips coined the term "milk of magnesia" in 1872 for an 8% w/v suspension of magnesium hydroxide.

6. How should I take Magnesium Hydroxide to work best?

   The right approach will give you maximum benefits from magnesium hydroxide. You should:

   • Drink a full glass (8 ounces) of water or milk with each dose

   • Take it before bed to relieve constipation by morning

   • Use it after meals and before sleep for heartburn

   • Mix liquid forms well before measuring

   • Use the provided measuring device instead of kitchen spoons