Febrile seizures, or convulsions, are common (up to 5% of children age 6 months-5 years) and you will see this if you work in ED or paediatrics (1).
- What is a febrile convulsion?
- Differential diagnosis – not all seizures with a fever are febrile convulsions (and did they even have a fever?)
- History taking – Take a history of the convulsion and a full medical history
- Examination – Perform a full examination, looking for neurology as well as signs of infection
- Red flags – actively seek these out
- So, I’ve got a well child with a typical febrile convulsion, I’m confident I have the source of the fever and that there are no red flags, what should I do?
- Education and safety netting is absolutely crucial:
- Some Case Examples Below
- Summary and final thoughts
- Further reading and references
What is a febrile convulsion?
There are two types, simple and complex:
- A simple febrile convulsion is a seizure occurring with a temperature of 38°C not associated with complex features and in the absence of intracranial pathology, occurring between the ages of 6 months and 5 years (2).
- A complex febrile convulsion is with the addition of one or more of the following features:
- >15 minutes long
- This does not mean you should wait for 15 minutes; a generalised seizure more than 5 minutes should be treated as status epilepticus
- Recurs within 24h
- Focal seizure
- Prolonged postictal drowsiness
- Postictal palsy (Todd’s palsy)
- Known epilepsy
- Previous afebrile seizures or developmental anomaly
The febrile state reduces seizure threshold and, in genetically predisposed children, causes a convulsion. They can be induced by any febrile illness, viral or bacterial, and have been reported after immunisation but this is rare (1).
Roseola infantum (HHV 6/7) is a classic cause of febrile convulsions and is characterised abrupt onset of a high fever for 3-4 days followed by a generalised maculopapular rash spreading from trunk to extremities as the fever subsides.
Differential diagnosis – not all seizures with a fever are febrile convulsions (and did they even have a fever?)
- Febrile convulsion
- Intracranial infection (e.g. meningoencephalitis, subdural empyema)
- Rigor (not a diagnosis per se)
- Epilepsy exacerbated by fever (epileptic seizures)
- Acute symptomatic afebrile seizure (e.g. hypoglycaemia/electrolyte disturbance, toxins, head injury)
- Always think about NAI in a young child with new onset seizures/reduced consciousness in the absence of another clear cause
- Other paroxysmal event
|Simple febrile convulsion||Meningoencephalitis||Rigor|
|Movement||Generalised tonic‑clonic +/- eyes rolled back||Generalised or focal||Shaking/shivering|
|Length||<15 mins (usually <5)||Usually >5mins requiring rescue||Variable|
|Post-event||Quick recovery (<1hr)||Prolonged drowsiness||No change|
|Other features||Underlying infection||Unwell, Irritable, Vomiting, Meningism (usually absent <18 months)||Underlying infection|
Beware that meningoencephalitis can present with very subtle or non-specific features in young children, but progresses quickly.
History taking – Take a history of the convulsion and a full medical history
History of convulsion:
- What was the child doing prior to the seizure?
- Any recent history of injury, particularly head injury.
- Any recent fevers, coughs, colds etc? – Clarify presence of fever
- How was the child eating and drinking prior to the convulsion? (e.g. could this have been due to hypoglycaemia)
- What were they doing with their: eyes, face, arms, legs.
- Was one side of their body affected or both sides?
- Any tongue biting / incontinence?
- How long did this last for? Did parents record a video?
- If paramedics were called, did they give medicine to terminate the seizure?
- Was there post-ictal drowsiness?
- Has the child fully recovered now?
- Are they complaining of any headaches / photophobia / neck stiffness?
- These questions will help you differentiate a febrile convulsion from differentials and you then need to focus on finding the source of the fever
- Febrile convulsions (after a first febrile convulsion, 30-35% of children go on to have repeated febrile convulsions with future febrile illnesses)/afebrile seizures/epilepsy
- Recent antibiotic use (may mask meningitis)
- Recent vaccination
- ?any recent foreign travel
Drug history, allergies, vaccinations
- A child is 10% more likely to have a febrile convulsion if a 1st degree family member also had febrile convulsions as a child
Growth and Development
- Any developmental concerns or delays?
Ideas concerns and expectations
Examination – Perform a full examination, looking for neurology as well as signs of infection
- General appearance – what are they doing? Do they look well or unwell? Are they still drowsy post-ictal? If so, how long since the convulsion? If the child appears drowsy or is showing any signs of persisting seizure activity call for help
- Respiratory – any signs of respiratory distress? Is there a cough? Auscultate for crepitations or wheeze which may occur as a result of infection
- Cardiovascular – Are they warm and well perfused? Check the cap refill time. If the child appears haemodynamically compromised (prolonged cap refill / tachycardic / hypotensive / mottled / cool peripherally) call for help
- Abdominal – Is the abdomen soft and non-tender? Causes of abdominal tenderness could be appendicitis or mesenteric lymphadenitis
- Lymph nodes – examine in the cervical and axillary chains for lymphadenopathy
- Neurocutaneous stigmata. These are signs of an underlying neurocutaneous disease such as tuberous sclerosis, neurofibromatosis or Sturge‑Weber. All of these conditions are associated with seizures
- Rashes – many childhood illnesses cause rashes, most are non-specific and benign but in a child with a high fever and no clear source you need to be sure you have properly examined for a non-blanching rash to exclude meningococcal sepsis
- DON’T EVER FORGET GLUCOSE – hypoglycaemia is a common cause of seizures and is common in itself in unwell children who are not feeding well.
- In young children neurology can mostly be assessed by observation: AVPU, behaviour, tone, posture, balance. Also assess for irritability, photophobia, neck stiffness
- In older child assess reflexes and examine for other signs of meningism such as Kernig’s sign
- ENT – If you can’t find a focus for infection elsewhere, chances are it will be otitis media or tonsillitis.
- Bear in mind that mastoiditis can track back and cause meningitis as can orbital cellulitis. Sinusitis is a cause of subdural empyema which would be on your list of differentials in a hot child with a seizure,
Red flags – actively seek these out
- “They’re just not right” – this might be you, the nurse, the parents or everyone.
- See fever in under 5s NICE guideline 
- No clear source (think harder – see case discussions below)
- Focal neurological deficit
- Prolonged drowsiness
- Any features of a complex febrile convulsion
- Developmental delay
- Neurocutaneous stigmata
- <6 months or >5 years (by definition, not a febrile convulsion and need to rethink)
- Family history of epilepsy in first degree relative
- Significant parental anxiety
- This should always be considered a red flag in paediatrics and is often a reason for overnight admission.
In general, you need to be more careful with children age <18 months as the features of intracranial infection are notoriously non-specific.
So, I’ve got a well child with a typical febrile convulsion, I’m confident I have the source of the fever and that there are no red flags, what should I do?
Generally, if it is their first episode, they get referred to paediatrics for assessment but the diagnosis is clinical, and routine investigation is not necessary. Most trusts have a local guideline for febrile convulsions which you can follow
Always speak to your senior before discharging and as a general rule, a senior review for all paediatric patients before discharge is useful.
Education and safety netting is absolutely crucial:
“Does my child have epilepsy?”
Short answer: No
Long answer: Still no, but with the caveat that 5% of children with complex febrile convulsions are subsequently diagnosed with epilepsy and the more atypical features, the higher the risk. Children with simple febrile convulsions are only at very slightly increased risk of epilepsy (1%) compared to the general population (0.5%) (1,2).
Epilepsy is defined as a disease of the brain characterised by either:
- At least two unprovoked seizures >24 hrs apart
- One unprovoked seizure with a high probability of further
- The diagnosis of an epilepsy syndrome.
Febrile convulsions in themselves can be recurrent but they are provoked and, by definition, are not epileptic seizures.
“What do I do if my child has another one?”
Seizures appear violent, dramatic, and are utterly terrifying to parents. They will now be worried each time their child has a fever. A third of children will go on to have at least another febrile convulsion (2).
- Safety net for seizure
- Recovery position
- >5 mins = 999
- Recurrence within 24hrs = return to hospital (now a complex febrile convulsion)
- Safety net for underlying illness
- Know fever in <5s NICE guidelines (3)
- Use What 0-18 website endorsed by RCPCH (4)
A good leaflet goes a long way!
“Can I prevent my child from having a febrile convulsion next time?”
Antipyretics cannot prevent a febrile convulsion. Anticonvulsants can prevent febrile convulsions, but because they are considered a benign phenomenon, are not used due to the potential for significant side effects (1).
Some Case Examples Below
You are the doctor covering paeds ED tonight and the paramedics have been busy…
Read the case examples below, think of your differentials and management plan and click on the box to reveal our answers
Summary and final thoughts
Simple febrile convulsions are common and benign. Rule out serious pathology, find and treat the source of the fever, and then educate, reassure, and safety net. Make sure to document what you have said/given to parents.
As for all paediatric presentations, always seek senior input from the registrar or consultant. Sometimes, things are not evident at first assessment and things can change rapidly in children which is why a period of observation can be so useful.
Further reading and references
- Leung AK, Hon KL, Leung TN. Febrile seizures: an overview. Drugs Context. 2018; 7:212536. Doi: 10.7573/dic.212536
- Capovilla G, Mastrangelo M, Romeo A, Videvano F. Recommendations for the management of “febrile seizures” Ad hoc Task Force of LICE Guidelines Commission. Epilepsia. 2009; 50(1): 2-6. Doi: 10.1111/j.1528-1167.2008.01963.x
- National Institute for Health and Care Excellence. Fever in under 5s: assessment and initial management. https://www.nice.org.uk/guidance/ng143
- Healthier Together. Febrile Convulsion advice intended for parents/carers taking their child home after seeing a doctor. https://www.what0-18.nhs.uk/professionals/gp-primary-care-staff/safety-netting-documents-parents/febrile-convulsion
Written by Dr George Aldersley Paediatrics ST2
Edited by Dr Rebecca Evans Paediatrics ST3
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1 thought on “Febrile Convulsions”
The case reports are really helpful in showing how to apply the knowledge in my clinical practice in the emergency department.