Generally all nutritional supplements are considered to be safe and well tolerable. However, few side-effects can generally occur including hypercalcaemia syndrome or Calcium intoxication (depending on the severity and duration of hypercalcaemia), occasional acute symptoms include anorexia, headache, dry mouth, nausea, vomiting, abdominal pain or stomach ache and constipation with the administration of Colecaciferol.