What is the definition of status epilepticus?
Five minutes or more of continuous seizure activity, or repeated seizures with no recovery of consciousness in between. That is the Intensive Care Society (ICS) definition, and 5 minutes is also when treatment starts. By then, a seizure is unlikely to stop on its own, and the longer it continues, the greater the risk that it becomes refractory.
Not just tonic-clonic seizures
Status epilepticus can be a prolonged seizure of any type (RCEM). The International League Against Epilepsy (ILAE) gives a different time to start treatment for each:
- Tonic-clonic: 5 minutes
- Focal, with impaired awareness: 10 minutes
- Absence: 10 to 15 minutes
Is this status?
Non-convulsive status epilepticus
Think of it when the patient isn’t waking up after a seizure, or the GCS isn’t improving, and look carefully for intermittent gaze deviation, nystagmus or subtle twitching (RCEM).
EEG confirms the diagnosis, but it isn’t an ED test: escalate to critical care and neurology. A benzodiazepine is usually the first treatment, but avoid over-sedation. The risk of injury and death from non-convulsive status is generally lower than from convulsive status, and heavy sedation can lead to an unnecessary intubation (NICE).
Is it an epileptic seizure or a functional seizure?
Functional seizures can look very like convulsive status epilepticus, and 1 in 10 people with functional seizures will present with apparent status (RCEM).
The witness account: history is key
A witness account or video improves the accuracy of the diagnosis (NICE NG217). Ask the patient and any witnesses what happened before, during and after the event, and phone witnesses who aren’t there. Patients with functional seizures commonly present with a relative or someone who knows them. They can help: they may have seen the patient’s seizures before, and can tell you whether this one looks different from the usual pattern. Record whether the eyes were open or shut, and whether the side or the tip of the tongue was bitten (NICE CG109). If a seizure happens in front of you, note the features yourself.
What set it off?
Ask about the lead-up. Functional seizures are dissociative, and functional status is more common after a recent traumatic event or with a psychiatric comorbidity. But RCEM warns against making the diagnosis on a psychological history or recent stress alone: it needs clear positive signs. In known epilepsy, status most commonly follows missed doses or a stopped or changed medicine; an intercurrent illness, a metabolic disturbance or a drug that lowers the seizure threshold can also set it off (RCEM).
The signs
Suggest a functional seizure:
- Eyes closed, resisting opening: the most reliable sign
- Long duration, although this helps less when you are already thinking of status, which is prolonged by definition
- Waxing and waning
- Asynchronous movements, although frontal lobe seizures can produce them too
- Side-to-side head movement
- Crying during or after the event
- Memory of the event
Supports an epileptic seizure:
- A bite on the side of the tongue: its absence doesn’t rule an epileptic seizure out
Doesn’t help either way:
- A bitten tongue without the site recorded
- Incontinence
- A raised lactate
In clinical doubt, treat
About 1 in 5 people with functional seizures also have epilepsy. RCEM warns that failing to treat genuine status because it is assumed to be functional is the far greater danger. In clinical doubt, err on the side of treatment, and reconsider the diagnosis at each stage. The paediatric algorithm builds this in: before the second-line drug, reconfirm that it is an epileptic seizure.
How do you manage status epilepticus in adults?
For adults, use the Intensive Care Society (ICS) guidance on the acute management of status epilepticus (2025), which is endorsed by RCEM and the Society for Acute Medicine. It covers patients over 16, but not pregnant women: a seizure in the second half of pregnancy is treated as eclampsia (see below). It sets out five stages, each with a time window and the team that should be involved.
- Open and maintain the airway: an oropharyngeal or nasopharyngeal airway if it can be inserted safely
- 15 L/min oxygen via a non-rebreathe mask
- IV or IO access; arterial gas and bloods
- Blood glucose below 4 mmol/L: correct it
- IV access: lorazepam 0.1 mg/kg, up to 4 mg (in 1–2 mg aliquots if over 70 or under 50 kg). Alternatives: midazolam 10 mg or diazepam 10 mg IV/IO
- No IV access: buccal midazolam 10 mg (5 mg if under 50 kg), or rectal diazepam 10 mg
- Wait 5 minutes, and get IV or IO access if not already done
- Choice depends on the patient: no evidence of a difference in effectiveness or safety
- Levetiracetam 60 mg/kg (max 4.5 g) over 10 min, or
- Sodium valproate 40 mg/kg (max 3 g) over 10 min, or
- Phenytoin 20 mg/kg (max 2 g) over 30–40 min, no faster than 50 mg/min (10–25 mg/min if elderly or possible cardiac disease)
- Refer to neurology. Maximal doses of the anti-seizure drugs, and continue the patient’s usual medication
- Propofol infusion (up to 4 mg/kg/hour) and/or midazolam (0.1–0.2 mg/kg bolus, then 0.05–0.5 mg/kg/hour, titrated to effect)
- Continuous EEG monitoring if possible
- Increase the propofol, then add midazolam, then lacosamide, then thiopentone
- Avoid opioid boluses: they are pro-convulsant
- Discuss with tertiary neurology, and consider transfer
Redrawn from the Intensive Care Society’s guidance for the acute management of status epilepticus in adult patients (2025), Figure 1 and Appendix 1.
Stages 1 and 2: the benzodiazepine
Which benzodiazepine depends on the route. With no IV access, give buccal midazolam (or rectal diazepam); with IV access, give lorazepam. The speed of delivery matters more than which benzodiazepine you choose, and lorazepam is the first choice in hospital because it acts quickly and causes less respiratory depression and sedation than the alternatives (NICE). If the patient has an individualised emergency management plan, follow it.
Two benzodiazepines, then a second-line drug. A third dose adds to the risk of sedation and respiratory depression, and delays the drug the patient needs.
Over-sedation can’t be reversed. Flumazenil is contraindicated in anyone with a history of epilepsy (RCEM and the National Poisons Information Service, NPIS), so be ready to support the airway and ventilation.
Also at stage 2, the small print: other important actions
- Continue the patient’s regular anti-seizure medication, and reverse any recent dose reductions. Take drug levels on admission if possible, but don’t omit doses while you wait for them.
- Treat the underlying cause, such as hyponatraemia or meningitis (see below).
- Give IV thiamine if there is a history of alcohol use or malnutrition: Pabrinex 2 pairs, or thiamine 300 mg IV, three times a day.
Which second-line drug should you give?
Once two doses of benzodiazepine have failed, give one of three drugs intravenously: levetiracetam, sodium valproate or phenytoin. They are equally effective and safe (ESETT trial, 2019), so the choice depends on patient factors. For example, valproate isn’t started in anyone under 55, male or female, unless two specialists agree.
| Adults (ICS) | Dose | Given over | What to know |
|---|---|---|---|
| Levetiracetam | 60 mg/kg, max 4.5 g | 10 minutes | Quicker to prepare and give, with fewer adverse effects than the alternatives (NICE) |
| Sodium valproate | 40 mg/kg, max 3 g | 10 minutes | Under 55: only if it’s in their specialist plan (below) |
| Phenytoin | 20 mg/kg, max 2 g | 30 to 40 minutes, no faster than 50 mg/min | The rate limit is there to avoid bradycardia, QT prolongation and arrhythmias; give it with cardiac monitoring. Elderly patients and those with possible cardiac disease: 10 to 25 mg/min. High pH: watch for extravasation from a peripheral line |
Levetiracetam is likely to be the preferred option, because it is quicker to give and has fewer adverse effects. Phenytoin is a close second.
Missed or vomited doses
Not taking medication as prescribed is a common cause of status in someone with epilepsy. If missed or vomited doses are suspected, consider reloading as per the algorithm (ICS), and keep the regular anti-seizure medication going alongside it.
If the patient takes one of the three drugs reliably, no national guideline says whether to load the same drug or switch, and local guidelines differ. Levels won’t decide it in the moment: RCEM advises saving serum for anti-seizure medication levels, and the ICS says to take levels on admission but not to omit doses while you wait for them. Some local adult guidelines calculate a phenytoin top-up from a recent level; levetiracetam levels aren’t routinely measured.
Under 55? Valproate only if it’s in their specialist plan
The Medicines and Healthcare products Regulatory Agency (MHRA) advises against starting valproate in anyone under 55, male or female, unless two specialists have independently agreed it’s the right treatment. In women and girls of childbearing potential, the Pregnancy Prevention Programme also needs to be in place. This applies to IV valproate too (NICE). In status epilepticus, that means giving it only if it’s already part of the patient’s neurology plan. If in doubt, choose levetiracetam or phenytoin.
What if the seizures continue after the second-line drug?
Status that doesn’t respond to one benzodiazepine and one non-benzodiazepine drug is refractory, and it needs critical care and IV anaesthesia (ICS). If the patient is still seizing after the first second-line drug, prepare for and perform rapid sequence intubation, give a second drug from the second-line list, and arrange transfer to ICU.
Stage 4, once the patient is intubated:
- Refer to neurology.
- Make sure the patient is on maximal doses of the anti-seizure drugs already given, and that their usual medication is continued where possible.
- Start a propofol infusion (up to 4 mg/kg/hour) and/or midazolam (0.1–0.2 mg/kg bolus, then 0.05–0.5 mg/kg/hour, titrated to effect).
- Start continuous EEG monitoring if possible.
Stage 5, beyond 60 minutes: super-refractory status needs agreement between the intensive care and neurology teams. Increase the propofol (to a maximum of 4 mg/kg/hour), then add midazolam, then lacosamide (200 mg IV loading dose), then thiopentone, ideally titrated to the EEG. Discuss with tertiary neurology and consider transfer.
Avoid opioid boluses (morphine, fentanyl, alfentanil) for seizure control: they are pro-convulsant.
NICE’s third-line options, once the second-line drugs have failed, are phenobarbital or general anaesthesia, both under expert guidance. In children, phenobarbital is one of the second-line alternatives (below).
How do you manage status epilepticus in children?
For children, use the Resuscitation Council UK (RCUK) algorithm for convulsive status epilepticus (February 2026). Its times run from the start of the seizure.
- Confirm clinically
- ABC, high-flow oxygen, monitoring, IV or IO access
- Blood glucose below 2 mmol/L: treat it
- Treat the underlying cause: infection, intoxication, raised intracranial pressure, electrolyte disorder, channelopathies
- 2 benzodiazepines maximum
- Midazolam 0.3 mg/kg buccal or intranasal, or 0.2 mg/kg IM (max 10 mg); or diazepam 0.5 mg/kg rectal (max 20 mg)
- IV or IO access: lorazepam 0.1 mg/kg (max 4 mg) or midazolam 0.15 mg/kg (max 10 mg)
- Reassess, and give the second dose: lorazepam 0.1 mg/kg IV/IO (max 4 mg) or midazolam 0.15 mg/kg IV/IO (max 10 mg)
- Reconfirm that it is an epileptic seizure, and prepare the second-line drug
- Levetiracetam 40–60 mg/kg IV over 5 min (max 4.5 g)
- Only if levetiracetam isn’t available: phenytoin 20 mg/kg IV over 20 min (max 1.5 g) with ECG monitoring; or phenobarbital 20 mg/kg IV, no faster than 1 mg/kg/min (max 1 g); or sodium valproate 40 mg/kg IV over 15 min (max 3 g)
- If preparation for deeper anaesthesia, with intubation and ventilation, is complete: go to the next step
- Or give a further alternative second-line drug (levetiracetam, phenytoin or phenobarbital)
- Ketamine, thiopental, propofol or midazolam, with a single dose of rocuronium if using neuromuscular blockade
- Consult a paediatric neurologist: EEG monitoring, consider brain imaging, and monitor for complications (respiratory and haemodynamic instability, renal dysfunction, metabolic disturbance, adverse drug effects)
Redrawn from the Resuscitation Council UK paediatric emergency algorithms (February 2026), “Treating convulsive status epilepticus in children”. Prefilled syringe doses from the buccal midazolam product licence.
Don’t forget non-accidental injury
In an infant, non-accidental injury must always cross your mind (RCEM). Look for unexplained bruising, or a vague or inconsistent history. A post-traumatic seizure, or a head injury where non-accidental injury is suspected, needs a CT head within 1 hour (NICE NG232). Follow your local safeguarding procedures.
The small print
- Children who have frequent seizures or status usually have an individually tailored plan. Follow it.
- Phenytoin given too fast causes bradycardia or asystole. Monitor the ECG and blood pressure, with caution in children with heart disease, arrhythmias or AV block.
- Avoid sodium valproate in pregnant teenagers (a pregnancy test is part of your work-up), and in suspected liver failure or metabolic disease.
- Monitor the glucose, aiming for 4 to 8 mmol/L.
- Measure the sodium, and treat it if below 125 mmol/L, with 3 mL/kg of 3% sodium chloride.
- In sepsis, consider measuring calcium and magnesium, as they can be low.
- Consider temperature control if the child is hyperthermic.
- Consider meningitis, encephalitis and raised intracranial pressure, and intracranial haemorrhage if there are signs of trauma.
- There is no evidence for an ideal third-line agent: thiopental, propofol, ketamine and midazolam can all be used.
Adults and children: the numbers that differ
| Adults (ICS 2025) | Children (RCUK 2026) | |
|---|---|---|
| Treat the glucose if below | 4 mmol/L | 2 mmol/L, then aim for 4 to 8 |
| Second-line choice | Levetiracetam, sodium valproate or phenytoin: equally effective and safe (ESETT), so the choice depends on patient factors | Levetiracetam; the others only if it isn’t available |
| Levetiracetam | 60 mg/kg (max 4.5 g) over 10 min | 40–60 mg/kg (max 4.5 g) over 5 min |
| Phenytoin | 20 mg/kg (max 2 g) over 30–40 min | 20 mg/kg (max 1.5 g) over 20 min |
| Phenobarbital | NICE third line, under expert guidance | A second-line alternative |
| Escalation | Urgent senior critical care review at stage 3 (15–30 min); RSI if still seizing after the first second-line drug | Call the anaesthetist and PICU at the second-line step (15–20 min); emergency anaesthesia no later than 40 min |
When is the standard drug the wrong choice?
In these patients, the usual second-line drug is the wrong answer, or another treatment comes first.
Seizing after an overdose
For seizures caused by a suspected overdose or poisoning, give benzodiazepines first, then use TOXBASE for second-line treatment. RCEM advises against phenytoin, because it blocks sodium channels. That matters because drugs such as tricyclic antidepressants (TCAs) already block them, and phenytoin adds to the risk of a broad QRS and arrhythmias.
Alcohol withdrawal seizures
In alcohol withdrawal seizures, give a quick-acting benzodiazepine such as lorazepam, and IV thiamine (doses above). Avoid phenytoin as the second-line drug (NICE CG100).
The second half of pregnancy
A seizure in the second half of pregnancy that can’t clearly be attributed to epilepsy is treated as eclampsia until proven otherwise (Royal College of Obstetricians and Gynaecologists, RCOG). Consider eclampsia after delivery too (RCEM). If there is doubt between epilepsy and eclampsia, give magnesium sulfate until a definitive diagnosis is made (RCOG).
- Loading dose: magnesium sulfate 4 g IV over 5 to 15 minutes
- Infusion: 1 g/hour, continued for 24 hours after the last fit
- Recurrent fits: a further 2 to 4 g IV over 5 to 15 minutes
Magnesium sulfate is the treatment. Diazepam, phenytoin and other anticonvulsants aren’t alternatives to it (NICE NG133). If the patient keeps seizing despite repeated magnesium, start an anti-seizure drug and consider other diagnoses. If the patient isn’t known to have epilepsy and there is no strong evidence that the seizure is eclamptic, they need a CT head and/or MR venography to look for other causes, including venous sinus thrombosis (RCEM). Our guide to obstetric emergencies covers pre-eclampsia and eclampsia.
Valproate and flumazenil
- Under 55, male or female: sodium valproate only if it’s in their specialist plan (above).
- Over-sedated by the benzodiazepines: flumazenil is contraindicated if they have epilepsy, as it can bring the seizures back, and in a mixed TCA and benzodiazepine overdose (RCEM/NPIS). Support their airway and breathing instead.
How do you find and treat the trigger?
At least half of patients presenting with status epilepticus don’t have epilepsy (ILAE). In adults, the commonest cause is cerebrovascular disease; in children, it is infection. In someone with known epilepsy, the commonest causes are missed doses, withdrawal of a drug, or a change in their medication (RCEM). The anti-seizure drugs treat the seizure, but the trigger will need its own treatment alongside them.
Metabolic causes
| Adults | Children (RCUK) | |
|---|---|---|
| Hypoglycaemia | Glucose below 4 mmol/L: give 100 mL of 20% or 200 mL of 10% glucose IV over 15 minutes, and recheck after 10 minutes. No IV access: give glucagon 1 mg IM, but remember it is less effective in alcohol misuse, malnutrition or chronic liver disease (Joint British Diabetes Societies, JBDS 2023). Always treat, and reassess. With a history of alcohol use, give IV thiamine as well. | Glucose below 2 mmol/L: give 2 mL/kg of 10% glucose IV or IO, and recheck after 5 to 10 minutes. Then aim for 4 to 8 mmol/L |
| Hyponatraemia | Ecstasy (MDMA) commonly causes it (RCEM 2025). A seizure is a severe symptom. Give 150 mL of 3% saline over 20 minutes, check the sodium, and repeat up to twice, aiming for a 5 mmol/L rise in the first hour and no more than 10 mmol/L in the first 24 hours. Severe symptoms are unlikely with a sodium above 130 mmol/L, so look for another cause (Society for Endocrinology) | Sodium below 125 mmol/L: give 3 mL/kg of 3% saline |
| Hypocalcaemia | Serum calcium below 1.9 mmol/L, or symptomatic: give 10 to 20 mL of 10% calcium gluconate IV over 10 minutes, with ECG monitoring, followed by an infusion (Society for Endocrinology) | In sepsis, consider measuring calcium and magnesium, as they can be low |
Poisoning
- Give benzodiazepines first, then use TOXBASE for second-line treatment, and avoid phenytoin (RCEM 2025).
- Tricyclics with a broad QRS: give 8.4% sodium bicarbonate, 50 mL for a QRS of 120 to 160 ms, and 100 mL for a QRS over 160 ms, VT or cardiac arrest (RCEM 2025).
- Severe local anaesthetic toxicity: give 20% lipid emulsion (Association of Anaesthetists). For any other poisoning, seek NPIS advice before giving it.
- Isoniazid: give pyridoxine. The dose is on TOXBASE.
- Hyperthermia above 38.5°C from poisoning: start active cooling and give benzodiazepines (RCEM 2025).
Infection
For suspected bacterial meningitis, take bloods and give antibiotics within 1 hour of arrival. Then stabilise the seizures, image, and only then do the lumbar puncture (NICE NG240). Give aciclovir if herpes simplex encephalitis is strongly suspected.
Further investigations
- CT head if there is no immediately apparent cause, such as non-adherence to medication (ICS).
- A post-traumatic seizure, or a child with a head injury in whom non-accidental injury is suspected, needs a CT head within 1 hour (NICE NG232).
- A pregnancy test in anyone of childbearing age (ICS).
- After a first seizure: a blood gas with glucose, ECG, FBC, U&E, calcium, magnesium, LFTs and CRP (RCEM 2024).
- In known epilepsy: save serum for anti-seizure drug levels, and let the local epilepsy team and the GP know about the attendance (RCEM 2024).
How the FRCEM Final tests status epilepticus
This is a consultant-level exam that assumes you can already treat a seizure with a benzodiazepine. The questions are about the next steps, the nuances of treatment and when to deviate from the standard algorithm.
- Read where the stem picks up. If two benzodiazepines have already been given, the next step is a second-line drug, not a third dose. In an adult still seizing after the first second-line drug, it is RSI and a second drug from the list.
- Use the algorithm that applies to your patient. Adults follow the ICS stages and children the RCUK timeline, and the thresholds and maximum doses differ.
- Look for the small details. Age, cardiac history, pregnancy, an overdose or missed doses can change which drug you select, its dose or how fast you give it.
- Look for the trigger. The next step may be treating the cause, not another anti-seizure drug.
- Is it epileptic? Use the witness account and the signs, but in clinical doubt, treat and reconsider at each stage.
- Know the later stages too. The patient may still be in the ED waiting for an ICU bed when the propofol infusion starts. You need to know the appropriate plan for any patient in your department, even if they are under the care of a specialist team.
When two second-line drugs both look reasonable, look in the stem for what separates them: an overdose, alcohol withdrawal, or a young woman who could become pregnant. For more on choosing between two answers that both look right, read Two answers look right: the FRCEM Final SBA trap, and how to beat it.
Go to the source
- The adult algorithm — Intensive Care Society, Guidance for the acute management of status epilepticus in adult patients (2025), endorsed by RCEM. Figure 1 and Appendix 1 are worth printing.
- The paediatric algorithm — Resuscitation Council UK, Paediatric emergency algorithms and resources (February 2026): “Treating convulsive status epilepticus in children”.
- The NICE recommendations — NICE NG217, Epilepsies in children, young people and adults: treating status epilepticus, repeated or cluster seizures and prolonged seizures.
- The definition — ILAE, A definition and classification of status epilepticus (Trinka et al., Epilepsia, 2015).
- Investigations and CT — RCEM, Recommendations for adults presenting to the ED with seizures (2024).
- Poisoning — RCEM, Management of patients with suspected but unidentified poisoning in the ED (2025).
- Eclampsia — NICE NG133, Hypertension in pregnancy, and RCOG Green-top Guideline 68, Epilepsy in pregnancy (2016).
- Metabolic triggers — Society for Endocrinology emergency guidance on severe and moderately severely symptomatic hyponatraemia (2022) and acute hypocalcaemia (2016), and JBDS, The hospital management of hypoglycaemia in adults with diabetes (2023).
- RCEM Learning — Status epilepticus (and its aetiology lesson) and Functional seizures.
- Functional status — Eilon et al., The A to F of functional status in the acute setting: a scoping review (Seizure, 2022).
Doses and thresholds here are a revision guide — always confirm against current guidance, the BNF, and your local protocol.
Practise the small print
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