Like all the other treatments for epilepsy, the ketogenic diet has some side effects, which may or may not affect a particular child. Some side effects may go away if caught and managed early on. Knowing what to look for can make a big difference. Reported side effects include dehydration, constipation, and, sometimes, complications from kidney stones or gall stones.
Adult women on the diet may have menstrual irregularities. Pancreatitis (inflammation of the pancreas), decreased bone density and certain eye problems have also been reported. Again, this is why the medical team closely follows children or adults who are on the diet.
The diet lacks several important vitamins which have to be added through supplements. Sometimes high levels of fat build up in the blood, especially if a child has an inborn defect in his ability to process fat. This possibility can lead to serious effects, which is another reason for careful monitoring.