[Update on the adverse effects during therapy with a ketogenic diet in paediatric refractory epilepsy]

The ketogenic diet is a non-pharmacological treatment that has been used as a therapeutic alternative for the management of refractory epilepsy since 1921. It is a diet, high in fats and low in carbohydrates, which is used to treat paediatric refractory epilepsy, and is effective in around 50% of the patients that begin to follow it. It is a nutrition plan that is imbalanced in terms of both macro- and micro-nutrients, which can give rise to nutritional deficits in energy, proteins, minerals and vitamins, as well as an excess of lipids. There is therefore a risk of it causing undesirable side effects both at the outset and in later stages of the treatment.

The most frequent adverse effects that may occur either in acute form or in later stages are described, and tools that can be used in their management and prevention during treatment are proposed for paediatricians and ketogenic diet teams.

Some adverse effects are difficult to interpret and may manifest due to involvement at different levels of the organism, thereby arousing doubts as to whether they are caused by the diet, the antiepileptic medication or by the patient's own intercurrent complications. It is important to follow the study and evaluation frequency protocol in order to detect and prevent these effects, as well as to consult reference centres in order to evaluate the cost-benefit of continuing the treatment or not.