Milk of Magnesia Uses

Uses of Magnesium Hydroxide

Milk of magnesia is a white inorganic compound with chemical formula Mg(OH)₂. Magnesium hydroxide has a very low solubility with K\[_{sp}\] = 5.61 x 10⁻¹². Milk of magnesia comes across as a mineral brucite when we talk about the natural occurrence. Magnesium hydroxide is named Milk of Magnesia because it has a milky appearance. In general, magnesium salts react with alkaline water to form magnesium oxide as a precipitate. For commercial preparation, seawater is treated with lime.


What is Milk of Magnesia Used for?

Milk of magnesia or Magnesium hydroxide has a varied range of uses in our daily life and practical applications. 

  • Clinical Uses - As an Antacid and Laxative 

Magnesium hydroxide facilitates bowel evacuation which is caused by distension produced by fluid accumulation because magnesium hydroxide draws water into the intestine (osmotic effect). The fact that magnesium hydroxide can cause bowel evacuation is used in surgery procedures that is, before the surgery. Magnesium hydroxide is used as an oral antacid which helps to neutralise the excess acid in the stomach. As an antacid, magnesium hydroxide is dosed around 1g for adults where it being a base, neutralises the acid present in the stomach. 


Magnesium hydroxide, when dosed around 2-5g, is used as a laxative. As discussed earlier, this medical property is used during constipation and pre-surgery requirements. This can also be termed as emulsion uses. Liquid paraffin and milk of magnesia oral emulsion is commonly called Cremag and is used as stool softener. Deys milk of magnesia uses are also popular as they are used to treat constipation.


What is Phillips Milk of Magnesia Used for?

Phillips milk of magnesia is used as a laxative which draws water into the intestine and further helps in the movement inside the intestine. It is used to treat casual short time constipation. It also acts as an antacid which is used to treat heartburns, upset stomach or indigestion. It can be consumed as a liquid or chewable form. Continuous usage of the Phillips Milk of Magnesia can cause adverse effects. Overuse makes the consumer excessively dependent on laxatives and further holds up the problem of constipation. Some other side effects include persistent diarrhoea, dehydration and mineral imbalances (high quantity of magnesium in the body).

[Image will be Uploaded Soon]


When to Take Milk of Magnesia

It is generally advised to take milk of magnesia during bedtime. People of all ages can consume a dose of milk of magnesia with water before going to the bed at night. A doctor must be consulted before giving it to a child below 6 years old.


Food Additive

Milk of magnesia is used in foods directly as it is generally considered safe. For commercial purposes, it is mostly sold as a medication in the form of tablets, capsules, liquid suspensions and powder. As antacids, they neutralise the stomach acid during digestion and acidity. As a laxative, it promotes easy evacuation of stools by softening it. Some magnesium hydroxides are further formulated including aluminium hydroxide to diminish the laxative effects. This inhibits the contraction of smooth muscle cells in the gastrointestinal tract and counterbalances the excessive contractions due to the osmotic effect.

FAQs (Frequently Asked Questions)

1. What are Some Other Uses of Magnesium Hydroxide (milk of magnesia) Other than Clinical Uses?

Other than clinical uses, magnesium hydroxide has various uses in different fields. Magnesium hydroxide is used as fire resistant and smoke suppressor, Natural magnesium hydroxide (brucite) is a natural fire retardant. In industries, there is synthetic manufacture of magnesium hydroxide. The property may be attributed to the endothermic decomposition at higher temperatures. The heat absorbed delays the ignition of the substance thereby retarding the fire caused. Magnesium hydroxide is also used to manufacture magnesia which is a poor electrical conductor and excellent thermal conductor. A vital component of antiperspirant is magnesium hydroxide. The powder of magnesium hydroxide is used as acid wastewater neutralisers. Magnesium hydroxide also alters the effect of drugs, either by increasing or by decreasing the effect of particular drugs. 

2. How to Make Magnesia Milk of Magnesia?

Milk of magnesia is formed by reacting different magnesium salts with basic or alkaline water. The milky precipitate formed is the white solid milk of magnesia. The chemical equation involved is:

2OH⁻ + Mg²⁺ → Mg(OH)₂ 

This method is applicable to manufacture milk of magnesia on a small scale. However, this method is not feasible or efficient enough for large scale manufacturing or commercial uses.  For commercial manufacturing of milk of magnesia, seawater is treated with lime or calcium hydroxide. An interesting observation is that 600 cubic meters of seawater can be used to manufacture an unit ton of magnesium hydroxide. Calcium hydroxide or lime being more soluble in nature does not precipitate and therefore, white magnesium hydroxide is obtained as a precipitate due to the treatment with seawater.