Abdominal pain, anorexia, diarrhea, irregular heartbeat, mood swings, nausea, weakness, painful urination, vomiting. If you have kidney or heart problems, do not take magnesium supplements without consulting a doctor. Cellulose sodium phosphate decreases magnesium's effectiveness. Magnesium reduces the absorption of ketoconazole and tetracycline. Magnesium can slow the urinary excretion of mecamylamine.
Vitamin D can increase magnesium concentrations in the body.
Do not take magnesium supplements during pregnancy or nursing without the advice of your health care professional.