Magnesium For Constipation

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Constipation is an intestinal disorder in which bowel motions are infrequent or difficult to pass. The stool is frequently firm and dry. Other symptoms may include stomach discomfort, bloating, and the sensation that one has not completed a bowel movement. Adults typically have three bowel motions per day to three bowel movements per week. It varies from 2-4 each day in younger children and newborns. Complications from constipation may include haemorrhoids, anal fissures, or faecal impaction, all of which can decrease the quality of life of one. Over the years, several management options have been used to treat constipation, this includes increased intake of water and fibres, laxatives (magnesium compounds), and enemas. In this article, we will endeavour to describe the action of popular laxatives: magnesium salts 

How does magnesium affect constipation?

Magnesium salts or alkalis used for the treatment of constipation are osmotic laxatives. Magnesium is poorly absorbed from the intestine; it pulls water from surrounding tissue via osmosis. This influx of water not only softens the faeces but also raises the faecal volume in the intestines (intraluminal volume), which stimulates intestinal motility naturally. Furthermore, magnesium ions promote the release of cholecystokinin (CCK), which leads to intraluminal water and electrolyte buildup, as well as enhanced intestinal motility. All these mechanisms help to increase the frequency of bowel movements, which helps to relieve constipation. 

Which magnesium is best for constipation

Magnesium is the fourth most common mineral in your body, although you may be deficient in it. Many people use supplements to increase their consumption. However, determining which kind is ideal for your requirements can be difficult. Most magnesium salts, in large quantities, can serve as osmotic laxatives, easing constipation. Magnesium salts that act as osmotic laxatives include:

  1. Magnesium citrate- Magnesium citrate is a magnesium salt that has been combined with citric acid. This acid occurs naturally in citrus fruits and contributes to their tart, sour taste. Magnesium citrate is among the most popular magnesium formulations, and it is widely available in pharmacies and online stores across the world. According to research, this is the most absorbed form of magnesium salts because it is easily absorbed by the intestines when compared to other forms.1 It is usually administered orally to replace depleted magnesium levels. Because of its natural laxative action, it is occasionally used to treat constipation at larger dosages
  2.  Magnesium oxide- Magnesium oxide is a salt formed by the combination of magnesium and oxygen. It naturally produces a white powdery material and is available in powder or capsule form. This form isn't commonly used to prevent or cure magnesium deficiency since, according to some research, it's barely absorbed by the gastrointestinal tract.2 However, it's commonly used for the quick treatment of unpleasant digestive problems such as constipation, indigestion, and heartburn
  3. Magnesium chloride- Magnesium chloride is a magnesium salt that is formed by a combination of chlorine and magnesium. It absorbs efficiently in the digestive tract, making it an excellent multi-purpose mineral. It can be used to treat magnesium deficiency, heartburn, and constipation
  4. Magnesium malate- magnesium malate contains magnesium and malic acid. Malic acid is naturally found in fruits and wine. magnesium malate is very readily absorbed in the digestive tract, making it an excellent choice for restoring your magnesium levels. However, it has a weaker laxative effect than others
  5. Magnesium sulphate- magnesium sulphate contains magnesium and sulphur. It is frequently referred to as Epsom salt. It's white and has a texture comparable to table salt. It can be used to alleviate constipation, but because of its awful taste, many individuals choose other sorts of digestive assistance
  6. Magnesium hydroxide- Magnesium hydroxide is an alkali available as a chewable tablet, tablet, and oral solution (liquid). It is commonly referred to as milk of magnesia. Magnesium hydroxide generally induces bowel movement between 30 minutes to 6 hours of administration. it is a short-term treatment for constipation in children and adults

Any of the above magnesium salts can be used for brief relief of constipation, however, each of them has its advantages over the others as stated above

How much magnesium should I take for constipation?

Magnesium has a maximum dosage of 2 grams (or 2000 mg). It is advised not to take more than four pills or capsules in one day. Magnesium is available in pill and capsule form (500 mg): it is recommended to be taken orally with a full 8-ounce glass of drink. One tablespoon of Magnesium Milk has 500 mg. Tablets and capsules can be taken together at bedtime or individually during the day.

Follow all product instructions or use as advised by your doctor. If you have any concerns, see your doctor or pharmacist. The dose is determined by your medical condition and reaction to treatment. Long-term or excessive usage of this drug for constipation may result in laxative dependency and chronic constipation. Overuse may also result in persistent diarrhoea, dehydration, and mineral imbalances.

Do not use magnesium salts without medical advice, especially if you have:

Side effects and other concerns

Magnesium compounds may aid in the treatment of constipation, but they may also have a few adverse effects. The following are common magnesium salts' adverse effects:

  • Abdominal cramps- Abdominal cramps/discomfort is pain that radiates from your chest to your groin. This is also known as the stomach area or belly
  • Nausea and vomiting
  • Intestinal gas
  • Hypermagnesemia (excess magnesium in the blood) - Taking higher-than-recommended dosages of magnesium salts with high bioavailability can result in hypermagnesemia. Because other magnesium salts have little bioavailability, it is reasonably safe, although long-term use may cause hypermagnesemia. Cases of magnesium salt-induced hypermagnesemia with significant consequences have been documented in recent years. The kidneys normally regulate blood magnesium levels; the normal range is 1.8-2.4 mg/dL, whereas values 3.0 mg/dL and higher are classified as hypermagnesemia. Hypermagnesemia has been linked to causing nausea, headache, light-headedness, and cutaneous flushing, with levels exceeding 12 mg/dL linked to respiratory failure, total heart obstruction, and cardiac arrest3
  • Milk-alkali syndrome- milk-alkali syndrome is characterised by hypercalcemia, metabolic alkalosis, and reduced kidney function due to absorption of alkali

Preventing constipation

While magnesium compounds can help alleviate constipation rapidly, they are not a long-term treatment. Preventing constipation may be the greatest strategy to minimize future symptoms and lessen the need for medicines such as magnesium salts or alkalis. Some ways to prevent constipation naturally include:

  • Drinking a lot of water to prevent dehydration
  • Adding more fibres to your diet
  • Frequent exercise to improve bowel movement


Constipation is common in most people, and it is typically not a reason for alarm. Magnesium compounds are generally safe to use for occasional constipation, and they usually act rapidly. However, magnesium compounds should never be used to treat persistent constipation. People who experience regular constipation should consult their doctor or pharmacist. Anyone who has negative effects from magnesium compounds or discovers that it does not work for them should speak with their doctor about alternate therapies.


  1. Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnes Res. 2003 Sep;16(3):183–91.
  2. Jp S, A H. Intestinal Absorption and Factors Influencing Bioavailability of Magnesium-An Update. Current nutrition and food science [Internet]. 2017 Nov [cited 2023 Jan 20];13(4). Available from:
  3. Mori H, Tack J, Suzuki H. Magnesium Oxide in Constipation. Nutrients. 2021 Feb;13(2):421. 

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This content is purely informational and isn’t medical guidance. It shouldn’t replace professional medical counsel. Always consult your physician regarding treatment risks and benefits. See our editorial standards for more details.

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Innocent Chijioke

Bachelor of Medicine, Bachelor of Surgery - MBBS, Medicine, University of IbadanUniversity of Ibadan, Nigeria

Innocent Dike is a final-year medical student at the University of Ibadan, Nigeria. He has more than two years of experience in research and health blog article writing. He serves as an ambassador for i-medics, where he trains his peers on blog article writing. presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
Klarity is a citizen-centric health data management platform that enables citizens to securely access, control and share their own health data. Klarity Health Library aims to provide clear and evidence-based health and wellness related informative articles. 
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