Ketogenic diet acute illness management

  • Introduction

    Ketogenic Diets (KD) are recognised treatment options for some children with refractory epilepsy and all children with Glucose Transporter Type 1 Deficiency Syndrome (GLUT1 DS).  The Royal Children’s Hospital (RCH) offers three types of ketogenic diet: the classical, MCT diet (medium-chain triglyceride diet) or modified Atkins diet (MAD). The KD has some potential side effects but is generally well tolerated.  

    In many instances, childhood illnesses can be managed at home, however when a child on a KD becomes unwell the illness and its effect on the diet requires assessment. Appropriate management is important to avoid the effects of excessive ketosis and to also avoid loss of ketosis from administration of high carbohydrate containing products. Loss of ketosis can result in exacerbation of seizures. Children on a KD will usually require hospital review if they present with any of the following: 

    • vomiting and diarrhoea 
    • febrile illness,
    • increased seizures.


      The aim of this guideline is to provide a framework for decision making in relation to the management of the unwell child on KD therapy.  

      Definition of terms 

      • Ketogenic Diet (KD): A very high fat, low carbohydrate, medically supervised diet used as a treatment option for some children with refractory epilepsy and all with GLUT1 DS.  The diet is calculated on an individual basis with specific dietary prescriptions for fat, protein and carbohydrate for each child. At RCH these diets are medically supervised by Neurology, Epilepsy Clinical Nurse Consultant and Ketogenic Diet dietitian.
      • Ketone bodies: Are water-soluble compounds that are produced when excessive amounts of fat are broken down for energy.  In some circumstances they are used as a source of energy in the heart and brain. 
      • Ketosis: a state in which the body is using ketones bodies by switching the body’s primary metabolism to a fat-based energy source rather than utilising glucose.
      • Oral Rehydration Solution (ORS): can be used to replace fluids and body salts. These solutions are composed of iso‐osmolar glucose electrolyte solution with base and citrate that is administered to treat dehydration. (eg GastrolyteTM, HYDRAlyteTM, PedialyteTM) 


      There are three key factors to the assessment of a child on KD therapy who is acutely unwell presenting to hospital for management.  

      1)           Child’s medical status

      • What is causing the child to be unwell?
      • Note: Any child who is septic, vomiting blood or bile or has severe abdominal pain needs IMMEDIATE assessment by a Consultant or Senior Fellow.
      • Take capillary gases, electrolytes, calcium, magnesium, phosphate, urea, glucose 

      2)           Level of hydration.

      • Assess degree of dehydration from clinical signs and change in body weight (if recent weight available) as per RCH Dehydration guidelines.

      3)           Assess  level of ketosis 

      • Measure serum ketone level (beta-hydroxybutyrate) by finger prick: usually maintained between 2.4-5.5mmol/L. 
      • Note that serum ketone levels above 5.5mmol/L are not necessarily concerning provided the child is not demonstrating clinical signs of excessive ketosis (see below).
      • Lower than usual levels of ketones are not a clinical concern and cannot be treated.
      • Families usually have a routine for measuring ketones when a child is well and will be able to report any changes.
      • Clinical signs of excessive ketosis include:
        • excessive fatigue or lethargy,
        • nausea,
        • vomiting,
        • very strong fruity smell on breath,
        • rapid panting/breathing,
        • an increased heart rate.

      Management of dehydration

      Oral Rehydration

      • Increase frequency of usual KD fluids (may include water, Ketocal® in correct ratio and others, check with dietitian if suitable fluids are being provided).
      • No regular soft drinks, milk, cordial, juices, are allowed.
      • Administer the Oral Rehydration Solution stocked at RCH (consider ORS icy poles as needed).
      • Rehydration is more important than any loss of ketosis the child may experience.
      • Strict fluid balance documentation in flowsheets. 

      Nasogastric rehydration

      • Used to rehydrate children if oral rehydration fails, ≥5% dehydrated, or significant ongoing losses.  
      • Nasogastric tube feeding can be run continuously or bolus feeds depending on clinical scenario and tolerance.   
      • Recommend calculations as per “RCH Gastroenteritis guidelines”. (see
      • Administer the ORS fluids or Suitable fluids (eg Ross Carbohydrate Free formula® (RCF) + additives ( Calogen, LiquigenTM), Ketocal®, or Ketovie®.)
      • Strict fluid balance documentation in flowsheets
      • Reassess child clinically at least hourly to two hourly until hydration status is stabilised.
      • Review fluid orders within 6 hours as per gastroenteritis CPG. 

      Intravenous rehydration 

      • Any child with severe dehydration (shock) may require immediate boluses as per Gastroenteritis CPG and then maintenance fluids adjusted according to clinical situation. Administer 0.9% Sodium Chloride only.
      • No IV glucose should be given (provided true BSL ≥2.6mmol/L as per Ketogenic Diet protocol) unless ordered by the on-call Neurology Consultant.
      • Strict fluid balance documentation in flowsheets .
      • Urgent investigations:
        • Urea & electrolytes
        • Glucose
        • FBE
        • Capillary blood gas
        • Urinalysis
        • Consider need for septic work up or surgical consult.
      • If serum sodium between 135mmol/L and 150mmol/L:
      • Contact General Medical Consultant:

      Management of excessive ketosis

      Excessive ketosis needs to be managed if there are high ketones in combination with clinical signs of ketosis.  It will usually require the administration of extra carbohydrate. (Guidance below assumes the carbohydrate content of 30ml of undiluted, non-diet apple juice = 30mL 10% Glucose intravenous fluid = 10mL oral sucrose 33% solution)

      Oral and nasogastric

      • Administer child 30mL undiluted, non-diet apple juice or10mLs oral sucrose solution 33%.
      • Retest serum ketones using finger prick 15 minutes after administration. 
      • If serum ketone level ≥ 6mmol/L and/or patient showing clinical symptoms of excessive ketosis, administer another 30mL undiluted, non-diet apple juice or 10mLs oral sucrose solution 33% and monitor clinical symptoms. 
      • If second dose of carbohydrate treatment does not result in improvement the child may require IV glucose bolus or maintenance.
        Once corrected and in ideal range, serum ketones will need to be monitored 6 hourly.
      • Blood glucose levels will need to be monitored at the same time as blood ketone levels or as clinically indicated. Aim for ≥2.6mmol/L.
      • Please inform the on-call Neurology team after the first carbohydrate treatment is administered.


      If ongoing excessive ketosis a child may require management with IV Maintenance 5% Dextrose and Normal Saline or IV bolus.
      In some situations, Plasma-Lyte 148® with NO dextrose may be clinically indicated.

      General Guidelines 

      • Medications  should be in tablet/capsule form as liquid preparations can contain high amounts of carbohydrates that are not compatible with a ketogenic diet. Speak to your ward pharmacist or medicines information pharmacist for advice about carbohydrate content in medicines. 
      • Excessive ketosis and well – no concern.
      • Excessive ketosis & drowsiness – assess for other medical factors contributing and if no contributing medical factor, then maintenance fluids of 5% Dextrose & Normal Saline.
      • Excessive ketosis & hypoglycaemia – follow hypoglycaemia guideline.
      • Any child on a ketogenic diet being admitted requires ketogenic team review and they need to be notified. Notify the multidisciplinary team for Dietitians, order specialty diet code ketogenic which links to Dietetics inpatient referral and notify Neurology team. 
      • Please inform the on-call Neurology team if high ketosis and child unwell. 


      Management of Acute Illness when on a Ketogenic Diet. 

      Please remember to read the disclaimer. 

      The development of this nursing guideline was coordinated by Jill Bicknell-Royle, Epilepsy Nurse Coordinator, Department of Neurology, and approved by the Nursing Clinical Effectiveness Committee. Updated November 2023.  

      Evidence Table 

      Reference (include title, author, journal title, year of publication, volume and issue, pages)

      Evidence level


      Key findings, outcomes or recommendations
       Thammongkol et al. (2012) Efficacy of the ketogenic diet: Which epilepsies respond? Epilepsia, 53(3):e55–e59. IV
      This review reports on efficacy and the epilepsy syndromes likely to respond to the ketogenic diet in children with refractory epilepsy. 
      The ketogenic diet is an effective treatment for children and adults with refractory epilepsy.
      Urine ketone levels maintained between 8mmol/L and 16mmol/L and serum ketone levels 2.4 5mmol/l were the aim.
      Kossoff et al. (2018) Optimal clinical management of children receiving dietary therapies: Updates recommendations of the International Ketogenic Diet Study Group.

      V This review provides international consensus for managing the ketogenic diet.
      Large urine ketones levels are optimal.
      It is reasonable to obtain serum ketones especially where urine ketosis is not correlating with expected seizure control.
      The risk of serious adverse effects whilst on ketogenic diet is low.
      Neal et all. (2008) The ketogenic diet for the treatment of childhood epilepsy: a randomised controlled trial. Lancet Neurol 7:500–506.
      II This review presents evidence from a randomized controlled trial that shows the ketogenic diet has efficacy and should be included in the management of children with drug resistant epilepsy. 
      The diet does have side effects including vomiting, abdominal pain and constipation.
      Kossoff EH, Turner Z, Doerrer SC et al. (2016) The ketogenic and modified Atkins diet: Treatments for Epilepsy and Other Disorders. Sixth Edition  New York: Demos Health   V This book represents management and information for undertaking a ketogenic diet. The authors are world leaders in ketogenic diets. Utilising practical and scientific referencing for management. 

      Van der Louw et al (2016) Ketogenic diet guidelines for infants with refractory epilepsy. European Journal of Paediatric Neurology. 20: 798–809. This review provides international consensus for managing the ketogenic diet and adds to planning during emergency situations. 
      Confirms use of ORS and hydration options.