[1] The underlying mechanism is not fully known, but it is thought to involve genetics, environmental factors, brain immaturity, and inflammatory mediators.

[7][8][6] The diagnosis involves verifying that there is not an infection of the brain, there are no metabolic problems, and there have not been prior seizures that have occurred without a fever.

[6] Outcomes are generally excellent with similar academic achievements to other children and no change in the risk of death for those with simple seizures.

[1] There is tentative evidence that affected children have a slightly increased risk of epilepsy at 2% compared to the general population.

[6] Signs of typical seizure activity include loss of consciousness, opened eyes which may be deviated or appear to be looking towards one direction, irregular breathing, increased secretions or foaming at the mouth, and the child may look pale or blue (cyanotic).

[5] Although the exact mechanism is unknown, it is speculated that these infections may affect the brain directly or via a neurotoxin leading to seizures.

[18] The risk is only slightly increased for a few days after receiving one of the implicated vaccines during the time when the child is likely to develop a fever as a natural immune response.

[21][22] The exact underlying mechanism of febrile seizures is still unknown, but it is thought to be multi-factorial involving genetic and environmental factors.

[6][7] Speculation includes immaturity of the central nervous system at younger ages, making the brain more vulnerable to the effects of fever.

[6] Other proposed mechanisms include the interactions of inflammatory mediators, particularly cytokines, which are released during a fever, causing elevated temperatures in the brain, which may somehow lead to a seizure.

[7] If a child has recovered and is acting normally, bacterial meningitis is very unlikely, making further procedures such as a lumbar puncture unnecessary.

[5][6][14] Differential diagnosis includes other causes of seizures such as CNS infections (i.e. meningitis, encephalitis), metabolic disturbances (i.e. electrolyte imbalances), CNS trauma, drug use and/or withdrawal, genetic conditions (i.e. GEFS+), FIRES, shivering, febrile delirium, febrile myoclonus, breath holding spells, and convulsive syncope.

[9] There is no evidence to support administering fever reducing medications such as acetaminophen at the time of a febrile seizure or to prevent the rate of recurrence.

[11] There is a decrease of recurrent febrile seizures with intermittent diazepam and phenobarbital but there is a high rate of adverse effects.

[1][3] Anti-seizure medication are used in status epilepticus in an effort to prevent complications such as injury to the hippocampus or temporal lobe epilepsy.

Evaluation for the cause of fever should be performed including signs of an infection such as a bulging tympanic membrane (otitis media), red pharynx, enlarged tonsils, enlarged cervical lymph nodes (streptococcal pharyngitis or infectious mononucleosis), and a widespread rash.

[citation needed] Long term outcomes are generally good with little risk of neurological problems or epilepsy.