Magnesium For IBS: Why It Is NOT For Every IBS Patient.


Magnesium is known for its laxative effect. it is found as supplement capsules, topical gel, and as a laxative oral solution and powder.

Some linked magnesium deficiency to IBS symptoms (especially constipation). and also, some recommend magnesium supplements for IBS patients.

What you will get from this article:

  • Is magnesium good for your IBS?
  • When to use magnesium laxative solutions for IBS?
  • When to take magnesium capsule supplements for IBS?
  • How magnesium can HURT your IBS?
  • signs you are low on magnesium
  • alternative ways to correct low magnesium without affecting your IBS.

Magnesium is mainly found in tissues. Only small fractions present in the blood. it serves many functions in maintaining healthy bones, muscles, and nervous system.

magnesium distribution

Data source: this study

1- Magnesium laxatives for IBS (powder and oral solutions)

Magnesium is a wonder element, it is the fourth most abundant element inside your body. Magnesium citrate (oral solution) is a laxative. It is a type of laxative that is called (Osmotic laxative). 


What osmotic laxatives do is that keeps water inside your intestine and prevent its absorption. Also, it may lead to the secretion of water from circulation into the intestine. This will make stool softer and produce a laxative effect for your IBS.

Magnesium citrate is an effective treatment for constipation including IBS-predominant constipation and Idiopathic chronic constipation.

When it comes to IBS, Using Magnesium Citrate oral solutions as a laxative is a late third option. This is because other options like fiber laxatives work better in alleviating symptoms of IBS other than constipation. And also, they generally will have fewer side effects profile.

And here is a break down of laxative options for IBS-C in order of ?preferability?: (reference)

The first option: Soluble fiber laxatives

A trial of soluble fiber laxative (namely Psyllium) is recommended as the first option to try with your IBS constipation. Psyllium (Metamucil) is a soluble fiber that is found to help with IBS-Constipation. It dissolves in water inside your intestine and forms a gel that not only acts as a laxative but also it can improve overall IBS symptoms including abdominal pain and gas (if taken in the appropriate doses together). Also, it is a safe, natural treatment with a good safety profile and fewer side effects.

The second option: Poly Ethylene Glycol (PEG):

Polyethylene Glycol (PEG) is an osmotic laxative (like Magnesium Citrate). It is used as a second option if your IBS-Constipation didn’t respond to Psyllium (Metamucil).

This is because PEG generally has fewer side effects compared with other osmotic laxatives (like magnesium citrate, Milk of Magnesia, and lactulose).

Also, it is inexpensive and widely available. Common side effects include bloating abdominal discomfort.

You can find the best laxative products on our resources page.

The third option: Magnesium as a laxative for IBS.

Magnesium for IBS comes third. We can use Magnesium citrate oral solution (250 mL once at a time) or Milk of Magnesia (Magnesium Hydroxide) as a laxative.

It acts as PEG as an osmotic laxative. It does good work for improving your IBS constipation. But the downside is that it may induce some abdominal pain and bloat; more commonly than fiber and PEG laxatives.

Also, some people may experience nausea and gastric upset. I usually spare Magnesium powders or oral solutions to the people who have IBS with occasional constipation or those who fail to respond to the first two options.

2- Is magnesium capsule supplements good for IBS?

There are 2 main reasons for taking magnesium while you have IBS:

  • For Improving IBS symptoms (which is not currently clinically approved).
  • For other health benefits of magnesium itself.

Magnesium capsule is widely used as a dietary supplement. that may provide benefits in a variety of conditions. But the question to ask here: are capsules containing magnesium good for IBS?

No sufficient studies on using Magnesium capsules for IBS. but it is generally considered a safe supplement with potential side effects specifically on people with IBS-Diarrhea

Using Magnesium capsule supplements (especially in low doses less than 300 Mg) may improve certain IBS symptoms. Most importantly constipation. Several studies studied magnesium? chronic constipation?. And the results are in favor of the use of Magnesium for constipation. (reference)

But “chronic constipation” is different from irritable bowel syndrome. People with chronic constipation only complain from constipation, unlike people with IBS who complain from different symptoms, mainly abdominal pain and bloating. (reference)

Although the benefit of magnesium supplements as a laxative. Yet no strong evidence from clinical trials that it can benefit IBS abdominal pain, gas, bloating, or IBS diarrhea.

Generally speaking, Magnesium capsule supplements are not bad for IBS. you can try it at small doses for your IBS. but I don?t recommend it if you have IBS diarrhea or consistently experiencing nausea with your IBS.

For IBS-constipation, You can consult your doctor about trying low dose Magnesium capsule supplements (start with 200 mg capsules once daily). But you have to watch out for any side effects or worsening of your IBS symptoms (constipation, abdominal pain, bloating, gas, and nausea). If your symptoms worsen after starting Magnesium capsules, then you should discontinue them. 

If you experience no change in your symptoms (constipation) you can gradually increase the dose. And stick to the dose with the best results and least side effects.

Magnesium for IBS works differently according to:

  • IBS subtype (constipation, diarrhea, Mixed or Undefined).
  • Magnesium-dose (larger doses cause side effects on IBS)
  • And also, individual variations.

Trial and error may be a solution to figure out if it works for your IBS or not. but what about taking magnesium for its other health benefits?  to when you should take magnesium, continue reading below.

3- Health benefits of Magnesium (other than IBS)

Magnesium is one of the wonder minerals, it is very abundant in your body, mainly found inside your cells (smaller amounts found in your blood)

Magnesium is essential to many body functions, you may frequently need magnesium for many reasons other than IBS. 

The benefits of magnesium: (reference) (reference)

1- It aids more than 300 enzymes inside your body to perform their functions: these enzymes regulate diverse functions inside your body including protein formation, muscle contractions, nerve functions, blood pressure, and blood glucose control.

2- Energy production.

3- Contributes to bone health and development.

4- required for DNA, RNA, and antioxidant glutathione productions. 

5- Studies showed that magnesium supplements lower blood pressure and protect from heart diseases (reference).

6- Magnesium lowers the risk of diabetes: diets with higher amounts of magnesium are associated with significantly lower diabetes risk (reference).

7- low magnesium levels may cause migraines: magnesium deficiency may promote the development of migraines (reference). However, research on taking a magnesium supplement to help migraines is still limited. This review suggested that taking 300 mg magnesium twice daily may help to prevent migraine attacks (reference).

benefits of magnesium

4- 10 Signs you are low on Magnesium

You may take a magnesium supplement to serve another need other than improving your IBS. before taking magnesium, I will try to explain signs you are low on magnesium.

The National Institute of Health (NIH) in the USA says that dietary surveys show that intakes of magnesium are lower than the recommended amounts. So, magnesium supplements may be needed in a large subset of people, including people with IBS.

Low magnesium may occur due to:

1- Decreased dietary intake.

2- Increased losses due to certain conditions like chronic diarrhea or malabsorption

3- Alcoholism.

4- Use of certain medications that can lead to magnesium deficiency like diuretics used in liver and heart diseases.

The signs that may indicate you need a magnesium supplement: (reference)

1- No symptoms: the NIH says that more commonly, magnesium deficiency has no symptoms because your kidneys limit the excretion of magnesium when you are low in magnesium.

2- loss of appetite (early sign).

3- Nausea or vomiting (early sign).

4- Chronic fatigue and weakness (early sign).

As the deficiency of magnesium worsens, you will start to experience more severe symptoms like:

5- Tingling and numbness in your limbs.

6- Muscle contractions and cramps.

7- personality and mood changes.

8- fits may occur in severe deficiency.

9- Heart problems including abnormal heart rhythms (arrhythmias) or coronary spasms (anginal attacks).

10- More severe magnesium deficiency is usually accompanied by a deficiency of calcium and potassium as well.

If you experience any of the above signs while you have IBS consult your doctor about its cause.  And it may be an indication that you need magnesium.

8- When to take Magnesium for IBS.

To summarize everything. I will gather the recommendations of taking Magnesium for IBS here.

1- Taking magnesium powder or oral solution laxatives for IBS: only take magnesium powder for the IBS-constipation subtype. And only take it only if you failed with fiber supplements like psyllium (Metamucil) and Polyethylene Glycol.

Take magnesium based laxatives only after consultation with your doctor as it may worsen other IBS symptoms like abdominal pain, diarrhea, gas, and boating.

2- Taking Magnesium capsule supplements for improving your IBS: you can try a low dose Magnesium supplement for IBS (200 mg once daily and increase the dose gradually).

  • Magnesium for IBS-Constipation (the best indication):  It may improve certain IBS symptoms especially IBS constipation. No evidence that it improves other IBS related symptoms like diarrhea, cramps, and gas.
  • Magnesium for IBS-Diarrhea: No scientific evidence supporting the use of magnesium for IBS-related diarrhea. Also, the overuse of magnesium may worsen IBS diarrhea. However chronic severe diarrhea may lead to magnesium depletion. But this pattern of severe diarrhea usually doesn’t occur with IBS-D. Always consult your doctor about using magnesium while you have IBS-D.
  •  Magnesium for IBS abdominal pain: Theoretically, it was supposed that magnesium relaxes the smooth muscles of your colon and prevents abdominal pain. But no scientific evidence from research supporting the benefit of magnesium for IBS abdominal cramps. As another factor that may contribute to the worsening of IBS pain with magnesium due to its osmotic laxative effects that may indirectly increase your gut motility and pain (especially at higher doses). Use it with caution and always consult your doctor.
  • Magnesium for IBS gas and bloating: Magnesium doesn’t seem to improve gas and bloating with your IBS unless caused by severe constipation. Low dose magnesium supplements will not cause affect gas and bloating (usually no worsening and no improvement). But higher doses may increase the sense of gas and bloat and may cause nausea. Rare cases reported the occurrence of (paralytic ileus) with very high doses of Magnesium supplements (reference).

To summarize the use of magnesium for IBS: the only evidence about magnesium is that it can benefit people with IBS-constipation. No strong evidence supports the use of magnesium for IBS-related diarrhea, abdominal pain, or bloating and distension.

3- Taking Magnesium capsules  for other health benefits while you have IBS:

Magnesium capsule supplements (like magnesium citrate, carbonate, glycinate) are not absolutely contraindicated with your IBS. But you have to use it with caution as it may worsen some IBS symptoms (especially in large doses). Always consult your doctor about using magnesium supplements for your IBS.

The perfect situation to take Magnesium capsule supplements includes:

  • IBS + chronic fatigue: chronic fatigue is commonly associated with IBS. also, chronic fatigue may be a sign of magnesium deficiency. You can try a magnesium capsule supplement even with your blood magnesium levels are normal. Normal blood magnesium levels are not an accurate measurement of your body’s magnesium stores (reference).
  • IBS + diabetes mellitus: Magnesium supplements are known for their benefits for lowering the risk of diabetes. Also, some evidence exists that taking magnesium supplements can improve your blood sugar control (reference).

So, if you are an IBS sufferer and at risk of diabetes (obese or have a strong family history) or you are already a diabetic patient, a magnesium supplement may be a good option (after consulting your doctor).

  • IBS + Migraine: IBS and migraine is a common association. You may benefit from taking a magnesium supplement (evidence discussed before).
  • IBS + Osteoporosis: Magnesium Plays a vital role in promoting healthy bones and preventing osteoporosis. Through its effect on active bone-forming and bone-decaying cells (Ostorblasts and osteoclasts). And also its effects on concentrations of parathyroid hormones and vitamin D (all essential for healthy bones) (reference). Taking a magnesium supplement for your osteoporosis and IBS may be a good idea. Consult your doctor about this.
  • IBS + Hypertension or Ischemic heart diseases: this may help both conditions (discussed before under magnesium health benefits).
  • IBS + alcohol dependant: alcohol dependence may cause magnesium deficiency. So if you consume alcohol while you have IBS. taking a magnesium supplement capsule is a good option.
  • IBS + other gut-related conditions: if you have other conditions affecting your gut together with IBS like previous intestinal resection (especially the ileum) or fat malabsorption. Taking magnesium may improve your condition. (reference).
  • IBS + old age:  older adults are at higher risk for hypomagnesemia due to 1- decreased dietary intake, 2- decreased intestinal absorption of magnesium, and 3- increased renal excretion of magnesium with age (reference). So having IBS in old age may benefit from magnesium supplement capsules.

Warning: It is not typical to have an IBS onset in older ages than 50. Always consult your doctor about your IBS and do the appropriate testing and investigations to confirm your condition.

5- Safety and side effects when taking Magnesium for IBS.

You have to consult your doctor before taking magnesium for IBS. No strong scientific evidence suggests the use of Magnesium for IBS-C. Generally, a magnesium supplement is a safe OTC medicine. But it may have some side effects on your IBS if not taken properly, such as:

1- Diarrhea: frequently encountered due to its laxative effect. Magnesium supplements may worsen your IBS diarrhea.

2- Also, Magnesium in large doses may worsen other IBS symptoms like bloating and gas.

3- It may cause nausea and stomach upset.

4- Large doses may cause side effects like low blood pressure, drowsiness, irregular heartbeats.


6- When NOT to take magnesium for IBS?


1- IBS with diarrhea: generally not recommended to take magnesium for IBS diarrhea. Unless prescribed by your doctor.

2- IBS + kidney disease: don’t take any magnesium supplements (unless prescribed) if you have kidney diseases. This is because Magnesium is mainly eliminated by your kidney.

3- IBS + severe nausea: Magnesium supplements may cause gastric upset and cause nausea or vomiting. Consult your doctor if it is necessary to take a magnesium supplement. 

4- Use with caution and take 2 hours apart if you are taking magnesium with one of these medicines:

  • Some antibiotics as quinolones, tetracyclines, aminoglycosides.
  • High blood pressure mediations as calcium channel blockers (for example Amlodipine)
  • Diuretics: medications that increase urine volume used with heart diseases, hypertension, liver diseases.
  • Muscle relaxants.
  • Bisphosphonates.
  • Thyroid medications
  • Chemotherapy drugs.
  • Other antacids.

If using any of the above drugs, consult your doctor before taking Magnesium.

NOTE: this is not a complete list of side effects and contraindications, please refer to your doctor and read the following resources:

Magnesium (WebMD).

Magnesium (

Summary of Magnesium for IBS:

Magnesium for IBSNotes
Laxative solution and powder containing magnesium for IBSIt can benefit IBS-constipation. But it’s a late is better to use fiber laxatives like Metamucil ? or PEG. (Fewer side effects)
Capsule supplements containing magnesium for IBS:It can benefit your IBS, especially the constipation-predominant type. But clinically proven benefits for IBS diarrhea, pain, gas, and bloating.
Using magnesium supplements while you have IBS:You can benefit from magnesium if you have IBS plus: chronic fatigue, migraines, diabetes mellitus risk or disease, hypertension, heart diseases, osteoporosis, older age.
Don’t use Magnesium for IBS when: If you have severe IBS diarrhea, taking other medications, have kidney problems, have gastric upset or nausea. Or magnesium supplements worsen your IBS.
Can Magnesium worsen IBS?Yes, especially in large doses. It can worsen IBS diarrhea, nausea, abdominal pain, and bloating.