Effects of taking too much magnesium include coma, blurred vision, fainting, trouble breathing, nausea and slow heartbeat, according to Mayo Clinic. Normal effects that some people experience include vomiting, stomach upset and nausea. However, people with good kidney function may not experience these symptoms.
For most adults, the right dosage of magnesium is less than 350 milligrams per day, says WebMD. Consuming too much magnesium is unsafe and causes it to build up in the body, leading to poor body function. Pregnant and breastfeeding women should seek proper medical advice on the right doses for magnesium. Too much magnesium increases the chances of bruising or bleeding since it tends to slow down blood clotting. Patients suffering from a heart block can suffer other medical complications if they take excess magnesium. Also, patients suffering from kidney problems can have severe effects due to poor clearing of magnesium from the body. Diarrhea may also occur but is less common, notes Mayo Clinic.
Magnesium interacts with other medications such as antibiotics, bisphosphonates, medications for hypertension, muscle relaxants and water pills, notes WebMD. Magnesium is taken by mouth to treat heartburn, magnesium deficiency, constipation and hypertension in pregnant women. Following the doctor's dosage instructions as per age and health condition helps to avoid overdose.