Minor side effects of taking magnesium include diarrhea and abdominal cramping, stomach upset, nausea, and vomiting. Signs of magnesium
toxicity may be similar to those of magnesium deficiency and include irregular heartbeat, changes in mental status, loss of appetite, nausea, diarrhea, muscle weakness, extremely low blood pressure, and difficulty in breathing.
You may be affected by the additives in the product perhaps.