“Documented adverse reactions reported in long-term ketogenic studies (any study that allows for keto-adaptation, which takes up to a month) include:

Gastrointestinal disturbances (diarrhea, vomiting, nausea, constipation, GER) Inflammation risk Sepsis, infection, bacteria overgrowth Pneumonia Acute pancreatitis Hypothyroidism Thinning hair/hair loss Menstrual irregularities and amenorrhea Hypoglycemia Increased cortisol Decreased testosterone Low platelet count Increased bruising Kidney stones Renal tubular acidosis Elevated liver enzymes Muscle cramps or weakness Impaired concentration/cognition Impaired mood Nutrient deficiency (most notably vitamin D, calcium, selenium, iron, potassium, phosphorous, vitamin C, magnesium and copper) Disordered mineral metabolism Poor growth in children Skeletal fracture Osteopenia/osteoporosis Shift towards atherogenic lipid profiles (including hypercholesterolemia and hypertriglyceridemia) Long QT intervals Cardiomyopathy Heart arrhythmia Myocardial infarction Death Studies report adverse reaction frequency ranging from 10% to 100%, which may reflect variations in the rigor of reporting in addition to the actual incidence in different populations. The extensive list of documented adverse reactions indicate that the positive health effects of a ketogenic diet comes at a cost, one that may not be acceptable to many. “

https://www.thepaleomom.com/adverse-reactions-to-ketogenic-diets-caution-advised/