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Magnesium Citrate Laxative


What Is Magnesium Citrate?

Magnesium citrate (also known as Citrate of Magnesia) is a laxative. It belongs to a family of laxative products known as "Saline Laxatives." These products are intended to evacuate the contents of our intestinal tract by stimulating bowel movements, usually within 1-6 hours. Magnesium citrate is typically recommended for one of two possible uses:

  1. Bowel evacuation prior to a rectal exam, like a colonoscopy
  2. The occasional treatment of constipation

This article is intended to provide some basic and practical information about the safe use of this product for patients who have been instructed to use it. I will divide this article into

  • Purchasing Magnesium Citrate
  • How to use it and what to expect
  • Possible Side Effects


The Ingredients from a typical bottle of Magnesium Citrate are as follows:

Active Ingredient:

  • Magnesium Citrate 1.745GM/ounce

Other Ingredients:

  • Citric acid
  • Lemon oil
  • Polyethylene glycol
  • Sodium bicarbonate
  • Sodium saccharin
  • Sucros
  • Purified water

Purchasing Magnesium Citrate

Where: Easy enough. Magnesium citrate is available over-the-counter in most U.S. pharmacies or grocery stores. You will typically find it in the section devoted to laxative products (near Metamucil, Dulcolax, Senokot, etc.). Look for it on the lower shelves, it usually comes in a glass bottle. NOTE: You may need to buy more than 1 bottle. Certain procedures require using 2-3 bottles. Additionally, you may also need to purchase a box of Dulcolax tablets (see the specific instructions given to you by your health care provider).

Flavors: Yes, you get a choice of flavors usually. Lemon-lime is the original flavor, but you may find it in grape or cherry also.

Cost: Bargain. It usually runs about $1.50 or $2.00 for a 10oz. bottle.


How It Works

Magnesium Citrate works by virtue of the "osmotic" pressure it creates in our intestines. The solution draws water from our body into the intestinal tract. Additionally, the ingredients in Magnesium Citrate may cause a direct irritation of the intestines, increasing motility and bringing about a bowel movement. Consuming sufficient amounts of clear fluid with Magnesium Citrate is critical to both its safety and effectiveness.

How to use it and What to expect

If you have been instructed by your doctor or gastroenterologist to purchase magnesium citrate in preparation for a colonoscopy, you will likely have been given a sheet of specific instructions indicating exactly when you are to begin using it.

Colonoscopy: An EXAMPLE of such instructions might be to drink ONLY clear liquids the day before your exam (e.g. water, ginger ale, clear broth, sports drinks, Jello, Popsicles, etc). On the evening before your exam you may need to take several Dulcolax tablets (another laxative) followed by the full bottle of Magnesium Citrate and several glasses of water (3-4 glasses typically). On the day of the exam, in the morning, you may need to repeat the above steps with another dose of Dulcolax and Magnesium Citrate.

NOTE: This is only an example. Follow the specific directions given by your prescriber or call their office for details.

Occasional Constipation: Magnesium citrate can be used to treat occasional constipation. It should not be used regularly. For this purpose, the entire contents of the bottle should be swallowed, followed immediately by at least 12 ounces of water. However - it should be noted that the treatment of constipation can almost always be approached with different methods such as increased fluids, stool softeners, fiber and sometimes stimulants. Magnesium Citrate is not something I personally recommend for routine constipation.

WHAT TO EXPECT: So...what is going to happen? The drink is somewhat sour, particularly the lemony one. Your stomach may feel just a little nauseous. Belching is not unusual. Typically, in about an hour, you will feel the urge for a bowel movement. These will continue, and you will have loose bowel movements over the next 24 hours most likely. Needless to say, you will want to stay near the bathroom.


Possible Side Effects

Magnesium citrate is usually well-tolerated. Stomach ache and cramping are not unusual, but this tends to be mild. Diarrhea, of course, is to be expected. Bloody diarrhea should be reported to your physician. Also, contact your doctor if the solution fails to produce a bowel movement within 6 hours.

Individuals with kidney disease should not use Magnesium Citrate.

Inform your doctor immediately if you develop hives or a rash following the ingestion of Magnesium Citrate.

Drug Interactions:

Certain medications may be affected by the use of Magnesium Citrate. For example, do not take alendronate (for osteoporosis), digoxin (for CHF) or tetracyclines (like doxycycline) within 2 hours of Magesium Citrate. Individuals currently being treated with quinalone antibiotics (e.g. ciprofloxacin) should not take Magnesium Citrate.


Colon Cleansing and Detoxification

No article on laxatives today would be complete without some comment on the popular idea of "detoxification" through colon cleansing. The idea is not new, dating to the late 19th and early 20th century. However, the data supporting the health benefits of regular colon cleansing with products like Magnesium Citrate are sadly lacking. Some studies have demonstrated possible immune system benefits, but as for long-term benefits we simply do not recommend this.

As a pharmacist, I remind patients that normal bowel movements are effective at ridding the body of whatever should not be there. The use of stimulant laxatives for purposes other than treating constipation or colonoscopy is not recommended.

I think Dr. Brooks Cash, chief of gastroenterology at the National Naval Medical Center in Bethesda, MD puts it well: “People will absolutely feel different after they have a colonic. They will feel lighter or cleaned out, whatever that means. But there is no evidence that our intestines clog like old metal pipes. Stool isn’t adherent like spackle. It’s constantly being pushed along for evacuation.”


Audrey Selig from Oklahoma City, Oklahoma on August 30, 2013:

Thank you for the excellent information on magnesium citrate. I am interested in taking it instead of magnesium oxide as a supplement. I read that the oxide does not have enough percentage of magnesium and to use citrate.

Jason Poquette (author) from Whitinsville, MA on June 12, 2012:


Yes, too acidic for you. Could try the Enteric Coated aspirin. That may help. Best wishes.

Anjili from planet earth, a humanoid on June 11, 2012:

A little acid isn't bad in the tummy. Aspirin really turns my tummy upside down until I have taken a glass of milk. It then subsides. Could it be described as too acidic for my tummy, or my tummy is to blame?

Jason Poquette (author) from Whitinsville, MA on June 10, 2012:

Hi Anjili,

Thank you. Well, of course, aspirin IS an acid of sorts. And many people find it bothers their stomach. What specifically do you mean by "too acidic?"

Anjili from planet earth, a humanoid on June 10, 2012:

Thanks for sharing your professional advice. I also like the way you decorate your hub. Tell me, why do I find aspirin to be too acidic unlike other people?

Shane from New Zealand on April 18, 2012:

I very much enjoyed this hub - Great Information & thankyou for writing this hub. Top Marks from me.

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