Prolonged seizures

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Intervention should occur after 5 minutes of seizure activity.

Patients with prolonged tonic clonic seizures that have lasted 5 minutes or more should be given:

  • Midazolam (Epistatus®) 10mg buccally or intranasally
  • OR Lorazepam 4mg intravenously if midazolam is unavailable
  • OR Diazepam 10mg intravenously or rectally if midazolam and lorazepam unavailable. 

If there is no response after 10 minutes, administer a repeat dose of benzodiazepine.

Establish aetiology:

  • If hypoglycaemia - 75mL of 20% glucose
  • If alcohol misuse or impaired nutritional status - Pabrinex® 2 pairs of ampoules (section 9.6)

Measure blood gases to assess extent of acidosis.
Check: FBC, U+E, LFT, Ca, Gluc, Clot, AED levels.
Administer usual antiepileptic medication in patients with established epilepsy. 

Within 30 minutes if seizures continue:

  • Intravenous sodium valproate* 20 to 30mg/kg rate 40mg/min
  • OR Intravenous phenytoin 18 to 20mg/kg rate 50mg/min with ECG monitoring (reduce rate if hypotension or arrhythmia), maximum per dose 2 grams. Refer to Guideline for phenytoin dose calculations

If status persists, then within 60 minutes:

  • Admit the patient to an intensive treatment unit and administer general anaesthesia
  • Refer for specialist advice. Midazolam, pentobarbital (unlicensed), propofol or thiopentone are most commonly used in these circumstances
  • EEG should be used to determine response to treatment.  

Further information:

* Valproate Pregnancy Prevention Programme: actions required now from GPs, specialists, and dispensers: Valproate medicines must not be used in women of childbearing potential unless the Pregnancy Prevention Programme is in place. If you are involved in the care of female patients on valproate in the UK, see a reminder of actions required for this medicine. You should have received a pack of information materials for patients—if you have not yet received a pack, or if you are near to running out of any materials, you should order more using the details provided in the article. See MHRA advice at

Editorial Information

Document Id: TAM286