According to research published in the journal Annals of Neurology, first seizures commonly last more than 10 minutes, and maybe as long as 30 minutes in children and adolescents.
The report found that the average first seizure lasted 12.2 minutes - around half of the first seizures reported lasted more than 5 minutes, around 29 per cent of first seizures lasted over 10 minutes and 12 per cent lasted over half an hour.
Researchers from the Epilepsy Management Center at the Montefiore Medical Center in New York studied over 400 children, ranging in ages from 1 month to 19 years and studied ambulance and medical records.
The research showed that 76 per cent of the cases had an average seizure duration of 3.6 minutes while the remaining 24 per cent of cases had a average duration of 31 minutes.
Report author Dr Shlomo Shinnar suggested that the data indicated that "once a seizure has lasted for 7 minutes, there is a greater than 95 per cent probability that it belongs to the second group and will last much longer", concluding that once a seizure has lasted 5 to 10 minutes, the need for intervention is indicated.