Dietary magnesium does not pose a health risk, however pharmacologic doses of magnesium in supplements can promote adverse effects such as diarrhea and abdominal cramping. Risk of magnesium toxicity increases with kidney failure, when the kidney loses the ability to remove excess magnesium. Very large doses of magnesium-containing laxatives and antacids also have been associated with magnesium toxicity.1
For example, a case of hypermagnesemia after unsupervised intake of aluminum magnesia oral suspension occurred after a 16 year old girl decided to take the antacid every two hours rather than four times per day, as prescribed. Three days later, she became unresponsive and demonstrated loss of deep tendon reflex.2 Doctors were unable to determine her exact magnesium intake, but the young lady presented with blood levels of magnesium five times higher than normal.3 Therefore, it is important for medical professionals to be aware of the use of any magnesium-containing laxatives or antacids.
Signs of excess magnesium can be similar to magnesium deficiency and include changes in mental status, nausea, diarrhea, appetite loss, muscle weakness, difficulty breathing, extremely low blood pressure, and irregular heartbeat.4 5 6 7 8
Table 5 lists the ULs for supplemental magnesium for healthy infants, children, and adults in milligrams (mg).9 Physicians may prescribe magnesium in higher doses for specific medical problems. There is no UL for dietary intake of magnesium; only for magnesium supplements.
Table 5: Tolerable Upper Intake Levels for supplemental magnesium for children and adults.10
| Age (years) | Male (mg/day) |
Female (mg/day) |
Pregnancy (mg/day) |
Lactation (mg/day) |
|---|---|---|---|---|
| Infants | Undetermined | Undetermined | N/A | N/A |
| 1-3 | 65 | 65 | N/A | N/A |
| 4 - 8 | 110 | 110 | N/A | N/A |
| 9 - 18 | 350 | 350 | 350 | 350 |
| 19+ | 350 | 350 | 350 | 350 |
Related Links: What is magnesium? | What foods provide magnesium? | How much magnesium do I need? | What happens if I do not get enough magnesium? | Do I need extra magnesium? | Can magnesium be harmful? | What are some of the current issues and controversies about magnesium?
Disclaimer
Reasonable care has been taken in preparing this document and the information provided herein is believed to be accurate. However, this information is not intended to constitute an "authoritative statement" under Food and Drug Administration rules and regulations.
About Source: ODS
The mission of the Office of Dietary Supplements (ODS) is to strengthen knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, disseminating research results, and educating the public to foster an enhanced quality of life and health for the U.S. population.
General Safety Advisory
Health professionals and consumers need credible information to make thoughtful decisions about eating a healthful diet and using vitamin and mineral supplements. These Fact Sheets provide responsible information about the role of vitamins and minerals in health and disease. Each Fact Sheet in this series received extensive review by recognized experts from the academic and research communities.
The information is not intended to be a substitute for professional medical advice. It is important to seek the advice of a physician about any medical condition or symptom. It is also important to seek the advice of a physician, registered dietitian, pharmacist, or other qualified health professional about the appropriateness of taking dietary supplements and their potential interactions with medications.
Email This Page 
Print This Page
Footnotes
- Xing JH and Soffer EE. Adverse effects of laxatives. Dis Colon Rectum 2001;44:1201-9. [↩]
- Jaing T-H, Hung I-H, Chung H-T, Lai C-H, Liu W-M, Chang K-W. Acute hypermagnesemia: a rare complication of antacid administration after bone marrow transplantation. Clinica Chimica Acta 2002;326:201-3. [↩]
- Xing JH and Soffer EE. Adverse effects of laxatives. Dis Colon Rectum 2001;44:1201-9. [↩]
- U.S. Department of Agriculture, Agricultural Research Service. 2003. USDA National Nutrient Database for Standard Reference, Release 16. Nutrient Data Laboratory Home Page, http://www.nal.usda.gov/fnic/foodcomp. [↩]
- Jaing T-H, Hung I-H, Chung H-T, Lai C-H, Liu W-M, Chang K-W. Acute hypermagnesemia: a rare complication of antacid administration after bone marrow transplantation. Clinica Chimica Acta 2002;326:201-3. [↩]
- Whang R. Clinical disorders of magnesium metabolism. Compr Ther 1997;23:168-73. PubMed abstract [↩]
- Ho J, Moyer TP, Phillips S. Chronic diarrhea: The role of magnesium. Mayo Clin Proc 1995;70:1091-2. PubMed abstract [↩]
- Nordt S, Williams SR, Turchen S, Manoguerra A, Smith D, Clark R. Hypermagnesemia following an acute ingestion of Epsom salt in a patient with normal renal function. J Toxicol Clin Toxicol 1996;34:735-9. PubMed abstract [↩]
- Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. National Academy Press. Washington, DC, 1999. [↩]
- Institute of Medicine. Food and Nutrition Board. Dietary Reference Intakes: Calcium, Phosphorus, Magnesium, Vitamin D and Fluoride. National Academy Press. Washington, DC, 1999. [↩]