Magnesium is one of the most abundant minerals in the body, essential in energy production, blood pressure and blood sugar regulation. protein synthesis and nerve, heart and muscle function.
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Although this mineral is naturally present in foods, magnesium compounds — such as magnesium citrate — may be recommended as a laxative or to counter a deficiency.
Since excess supplemental magnesium can lead to toxicity, it's important to follow recommendations on how much and how often to use this supplement. How often you take magnesium citrate and how much will depend on why you're taking it along with your doctor's input.
What Is Magnesium Citrate?
Magnesium citrate, a compound of magnesium and citric acid, is a common way to supplement this mineral, as it's inexpensive and well absorbed by the body.
This magnesium salt contains 16 percent elemental magnesium, an important factor to remember when reading the supplement facts label — which details the amount of magnesium found in each serving. Magnesium citrate is available without a prescription and can be purchased in pill, powder and liquid form.
What Is Magnesium Citrate Used For?
Magnesium citrate is commonly used as a laxative and for treatment of magnesium deficiency. And because deficiency of this mineral is associated with cardiovascular disease, diabetes, migraines, asthma and pregnancy complications such as eclampsia, your doctor may recommend magnesium supplementation if you have one of these disorders.
But on the other hand, since too much magnesium can be toxic, it's important to follow recommendations for correct dosing, including frequency of use.
Magnesium Citrate Dosage to Treat or Prevent Deficiency
If you have a magnesium deficiency, or if you are at risk of developing low levels of magnesium in your body, your doctor may recommend supplementation with magnesium citrate tablets — and counsel you on safe and effective dosing.
Unless otherwise recommended by your doctor, the supplemented magnesium citrate dose should not be higher than the Tolerable Upper Intake Level (UL) of 350 milligrams of elemental magnesium per day, as established by the Food and Nutrition Board at the Institute of Medicine of the National Academies.
Magnesium may be taken in single or divided daily doses and can be safe for most people to use daily — in doses at or below the UL. However, it's good practice to discuss long-term use of this supplement with your doctor.
Magnesium Citrate Dosage for Constipation
Magnesium also functions as a laxative, since its presence in the gut attracts water, making stools more watery and stimulating bowel movements. A single dose of the most common strength of liquid magnesium citrate, which for adults is 5 to 10 ounces — or 1.4 to 2.8 grams of elemental magnesium — may be used to treat occasional constipation, producing results within six hours.
Since this dose is 4 to 8 times the UL, this treatment should only be used occasionally and not for management of ongoing constipation. Follow package directions, as different strengths may be available, and be sure to drink a full glass of water along with the magnesium citrate to avoid upsetting your stomach.
Magnesium Citrate Dosage for Bowel Cleansing
Emptying the bowel of fecal contents, or bowel cleansing, is essential prior to a successful colonoscopy, or other imaging of the intestines. While polyethylene glycol (PEG) and oral sodium phosphate are the most common bowel preparations, magnesium citrate may also be recommended alone or in combination with half the usual dose of PEG.
To use magnesium for bowel preparation, follow your doctor's advice on dosing, which usually involves drinking the prescribed laxative in two doses, starting the afternoon or evening before your procedure. Be sure to drink plenty of water along with your bowel preparation laxative.
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The Symptoms of a Magnesium Deficiency
Assessing magnesium deficiency is challenging because most of the body's magnesium is stored in the bone or inside body cells — not in the blood, where it can be most easily measured. Severe magnesium deficiency is not common, but mild to moderate deficiencies are more likely to be found in the U.S. population.
Since every cell in the body requires magnesium, and this mineral plays a role in many body functions, prolonged low dietary intake can lead to deficiency symptoms. Initial signs include:
- Nausea and vomiting
- Loss of appetite
- Weakness, lack of energy and fatigue
More pronounced deficiency can lead to generalized symptoms including anxiety, depression, headaches, sleep disorders, hyperactivity, and can potentially affect many body systems, causing symptoms such as:
- Muscle spasms or cramps
- Nervousness, poor memory, seizures, tremor or vertigo
- Numbness and tingling
- Heart rhythm abnormalities
- Pregnancy complications such as eclampsia and premature labor
Magnesium deficiency can also affect bone health, contribute to worsening of blood cholesterol, blood sugar and blood pressure levels, and is linked to constipation, chronic fatigue syndrome and asthma.
Side Effects of Magnesium Citrate
If the correct dosing is followed, magnesium citrate can be well tolerated. However, gastrointestinal side effects could occur, including:
- Loose stools or diarrhea
- Stomach cramps or upset stomach
- Abdominal gas
Read more: 7 Signs Your Gut Is Out of Whack
Magnesium Citrate Drug Interactions
Taking magnesium at the same time as some other medications can alter drug absorption, and certain drugs can affect body levels of magnesium — and influence supplement requirements.
For instance, if you're taking certain antibiotics, muscle relaxants or blood pressure medications, or if you are taking alendronate (Foxamax), a common osteoporosis medication, you may need to space these medications at least 2 hours apart from your magnesium supplements.
Using magnesium along with certain diuretics or medications that minimize urinary loss of nutrients can lead to increased body levels of magnesium. If you're taking any prescription medications, discuss potential interactions or safety issues with your doctor.
- Let your doctor know if you are taking magnesium citrate on an ongoing basis, and if your doctor recommends you use this supplement, follow dosing directions.
- Don't use magnesium citrate or other laxatives as a means to lose weight, as this is a dangerous practice that can lead to severe dehydration, electrolyte abnormalities, organ damage and even death.
- If you have ongoing constipation which is not relieved a high-fiber diet, increased fluid intake and by occasional use of liquid magnesium citrate, see your doctor.
- If you have kidney disease, magnesium supplements are more likely to lead to toxicity, so avoid magnesium citrate unless specifically recommended by your doctor.
- Finally, if you experience an allergic reaction after using magnesium citrate, such as hives, swelling or difficulty breathing, seek immediate medical attention.
- National Institutes of Health: Office of Dietary Supplements: Magnesium
- Nutrients: Magnesium in Prevention and Therapy
- Advances in Nutrition: Magnesium in Disease Prevention and Overall Health
- American Family Physician: Management of Constipation in Older Adults
- American Family Physician: Therapeutic Uses of Magnesium