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Side-effects of the Ketogenic Diet


Short-term side-effects during KD initiation:

When a child starts on the Ketogenic Diet, they may feel lethargic and lack energy for several weeks. During the initiation period on the diet, they may also experience the following easily treatable, but potentially serious side-effects:



Side-effects associated with KD over the longer-term

If a child remains on the diet over a longer period of time, as with any medical therapy, they may experience adverse effects. Some of these include:

  • Kidney stones
  • Constipation
  • Dehydration
  • High blood cholesterol and triglyceride levels
  • Slowed growth or weight gain
  • Bone fractures
  • Vitamin deficiencies (e.g. selenium, vitamin D, zinc etc.)



All of the above possible side-effects should be monitored in patients on the Ketogenic Diet (see: Initial Screening & Monitoring required during diet).


Typically, children come off the Ketogenic Diet after around two years [1].  However, if there is no improvement after three months, the ketogenic diet is often abandoned. The treating Neurologist will determine when the diet will be discontinued and the method for gradual discontinuation.




This page was created on the 20th February 2015. It was last reviewed in December 2017.


[1] Martinez, C. C., Pyzik, P. L. and Kossoff, E. H. (2007), Discontinuing the Ketogenic Diet in Seizure-Free Children: Recurrence and Risk Factors. Epilepsia, 48: 187–190. doi: 10.1111/j.1528-1167.2006.00911.x