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Milk of Magnesia: Antacid and Laxative

Mohommed Essop-Adam
Reviewed by Mohommed Essop-AdamReviewed on 30.10.2023 | 4 minutes read

Milk of Magnesia is a well-known remedy that has been around since 1873. It is also known as Phillips’ Milk of Magnesia because it was developed by an English pharmacist called Charles H. Phillips.

It is a popular medicine that is used to relieve indigestion, it also an effective laxative for treating constipation. The name Milk of Magnesia is used because the product comes as a white liquid that resembles milk and it contains magnesium (in the form of magnesium hydroxide).

Doctor’s advice

Who is it for?

Milk of Magnesia is used to relieve indigestion symptoms, such as feeling bloated and full, flatulence, abdominal pain and discomfort and heartburn. Indigestion tends to be the result of over-indulgence. It can also be used as a laxative. You can expect to have a bowel movement between 30 minutes to 6 hours after taking Milk of Magnesia. For this reason, some people like to take Milk of Magnesia at bedtime to avoid suddenly needing to go to the toilet when they are out during the day.

Milk of Magnesia is suitable for adults and children aged 3 and above, and it is a medicine for short-term use only. You should not use Milk of Magnesia for longer than 3 days for constipation or 2 weeks for indigestion

How does it work?

Magnesium hydroxide is the active ingredient in the product, and it works as both an antacid to relieve indigestion and a saline laxative to relieve constipation.

Antacids like magnesium hydroxide relieve symptoms of indigestion by neutralising stomach acid. This helps because indigestion is often caused by your stomach producing too much acid, which can irritate the lining of your stomach, causing symptoms. Stomach acid can also travel up and irritate the lining of your oesophagus (food pipe), resulting in a burning feeling in your chest (heartburn). Antacids are usually fast-acting, and liquid antacids, such as Milk of Magnesia, tend to work faster than antacids available as chewable tablets.

Magnesium hydroxide helps relieve constipation by drawing water into your intestines. This helps stool on its way by making it softer and easier to pass.

Should anyone avoid Milk of Magnesia?

Do not use Milk of Magnesia if you are allergic to magnesium hydroxide or another listed ingredient. You should not give Milk of Magnesia to children under 3 unless a doctor has recommended this.

You should speak with your doctor before taking Milk of Magnesia if you are pregnant or breastfeeding, or have kidney problems.

Milk of Magnesia can interact with other medications like certain antibiotics (called tetracyclines and quinolones). If you take any prescription, over-the-counter, or herbal medicines, you should ask your doctor or pharmacist whether it is safe for you to take Milk of Magnesia. They may recommend you take your usual medications at a different time to Milk of Magnesia.

Are there any side effects?

Sometimes, due to its laxative effect, Milk of Magnesia can cause diarrhoea. Abdominal pain is another side effect that has been reported.

Due to the magnesium content in Milk of Magnesia, it can also cause a condition called hypermagnesemia, where the concentration of magnesium in your bloodstream is too high. The incidence of this side effect is rare. However, it is more common in people with kidney problems, especially if they take the medicine for a long time. This is why people with kidney problems should speak with their doctor before taking Milk of Magnesia.

Hypermagnesemia causes symptoms such as nausea, vomiting, flushing and headache and can be very serious if not treated promptly. Your kidneys usually remove excess magnesium from your body when it is no longer needed. However, if you have kidney problems, then they are less capable of removing the excess magnesium from your body, so it can build up in your bloodstream. You can always get a test to see how well your kidneys are functioning.

Young children are also more susceptible to developing hypermagnesemia. It is also more common if you are dehydrated. Therefore, it is important that you stay hydrated when taking the medicine.

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Mohommed Essop-Adam
Reviewed by Mohommed Essop-Adam
Reviewed on 30.10.2023
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