Trade/other name(s): Citrate of magnesium, MagCitrate
Why would this drug be used?
Magnesium citrate is used to treat constipation. You can buy it over the counter, without a prescription.
How does this drug work?
Magnesium citrate is a hyperosmotic saline laxative. That means it pulls water from the tissues into the small intestines. The movement of water stimulates the normal forward movement of the intestines (known as peristalsis), usually resulting in a bowel movement within ½ to 3 hours. Smaller doses may work more slowly, especially if taken with food.
Before taking this medicine
Tell your doctor…
- If you are allergic to anything, including medicines, dyes, additives, or foods.
- If you have nausea, vomiting, rectal bleeding, unexplained abdominal pain, or any disease of the stomach or intestine. Something besides constipation may be causing your problem.
- If you have heart disease or high blood pressure. Magnesium citrate may cause you to retain fluid and make your heart work harder, which can worsen these problems.
- If you have kidney disease. Magnesium citrate may cause the potassium or magnesium level in your blood to get too high.
- If you are pregnant. Magnesium citrate may cause you to retain more fluid.
- About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.
Interactions with other drugs
Magnesium citrate can cause certain medicines to not work as well: blood thinners, such as warfarin (Coumadin), digoxin and similar heart medicines, and phenothiazines, such as chlorpromazine, haloperidol, perphenazine, pimozide, thioridazine, and others. Magnesium citrate should not be used if you are on any of these medicines.
If you are on ciprofloxacin (an antibiotic), etidronate (used for bone problems), or sodium polystyrene sulfonate (Kayexelate), you should not take magnesium citrate. It keeps these medicines from working.
If you are taking tetracycline (an antibiotic) you should not take magnesium citrate within 2 hours of it.
Other medicines may not work as well if taken at the same time as laxatives. Do not take this medicine within 2 hours of your other medicines.
Interactions with foods
Although magnesium citrate works faster when taken on an empty stomach, no serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.
Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.
How is this drug taken or given?
Magnesium citrate is given as a liquid by mouth, which can be mixed with water or juice. The dose depends on how well the magnesium citrate works for you and the reason you are taking it. You should refrigerate magnesium citrate before using. Drink two glasses of cold water or other liquid after you take it, to replace the liquid you will lose. Take this drug exactly as your doctor or health team tells you, or follow the directions on the label. If you have any questions or do not understand the instructions, talk to your doctor, nurse, or pharmacist.
Store the medicine in a tightly closed container away from heat and moisture and out of the reach of children and pets.
Laxatives can cause diarrhea, which can result in loss of fluids, nutrients, and electrolytes. If you have diarrhea, it is important to replace the fluid that you lose by drinking 2 to 3 quarts of fluid a day. Fluids with electrolytes, such as broth or sports drinks, can help replace the potassium and salt lost in diarrhea. If you have symptoms of electrolyte imbalance, such as dizziness, confusion, lightheadedness, irregular heartbeat, muscle cramps, unusual tiredness or weakness, call your doctor.
Some forms of magnesium citrate contain sugar. Check with your pharmacist about the ingredients if you have diabetes.
If you are taking opioid pain relievers, you will need to take laxatives regularly to counter their action on the bowel. This helps to prevent severe complications such as impaction or blockage. Talk to your doctor or nurse about the best laxatives to use and how to take them. Let your doctor or nurse know if you haven't had a bowel movement for 3 days.
If you are not taking opioid pain medicines, and you use laxatives often, the body can forget the normal process of moving your bowels. You then depend upon the laxative for a bowel movement. If this is a problem for you, talk with your doctor.
Besides taking laxatives, there are other ways to help prevent constipation. Try to drink 2 to 3 quarts of fluid a day, increase the amount of fruits and vegetables in your diet (try to eat at least 5 servings daily), and eat bran cereals. You should also try to do gentle exercise as much as you can.
Possible side effects
You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.
- loss of normal bowel response when used on a long-term basis*
- abdominal pain or cramping
- dehydration resulting from diarrhea*
- loss of electrolytes from diarrhea*
- High magnesium or potassium levels in the blood if kidneys don't work well; may cause dizziness or lightheadedness.
There are some other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.
This drug appears to pre-date the current FDA approval process, which would mean it was not required to get formal FDA approval.
Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.
Last Revised: 09/11/2009