A petit mal is a type of seizure that occurs most often in those younger than 20. The petit mal seizure is characterized by an abrupt but brief interruption in consciousness, accompanied by small jerks of the hands or facial muscles. Because of the lack of awareness patients with this type of seizure experience, a petit mal is sometimes called an absence seizure.

Symptoms of petit mal seizures can be hard to observe because the seizures themselves are so brief - often only a few seconds. The patient will often appear simply to be staring into space. Some more outward indications of a petit mal typically include smacking of the lips or chewing, hand movements, and fluttering eyelids. During this time, the patient will have no awareness of his or her surroundings and will be unable to continue conscious activity such as movement or talking. Atypical symptoms can include slumping or falling, with a more gradual onset and recovery than a typical petit mal.

Full recovery is practically instantaneous; however, the victim has no memory of the episode. Because petit mals are so brief and their symptoms can be subtle, their first indication in a child may be unexplained difficulties in school or an inability to focus. Sufferers of petit mal seizures are sometimes incorrectly diagnosed with learning disabilities.

The disturbance in brain function that indicates a petit mal is caused by abnormal electrical activity in the brain. Brain cells produce electrical discharges during waking and sleeping. If these discharges fall out of synchronization, a seizure occurs. However, it is usually hard to diagnose the cause of this abnormal brain activity. Some known causes include disturbances of the metabolism, such as kidney or liver disease; low levels of sodium, magnesium, or calcium; previous brain trauma; birth defects in the brain; and heredity.

If one observes a petit mal for the first time or if the seizures appear to last longer than two minutes, one should seek medical attention. A doctor may take a blood test to look for a chemical imbalance, take a magnetic resonance image or MRI to rule out brain disorders, or use electroencephalography (EEG) to measure the brain's electrical activity under stimulation, such as a light being flashed in the eyes. Anticonvulsant medications can be prescribed by a physician to reduce or eliminate petit mal seizures. Petit mal seizures are most common in children, many of whom outgrow them and are able to discontinue medication as they reach adulthood. A small percentage of petit mal sufferers progress to epilepsy, but most are able to live with few restrictions, such as avoiding driving or strenuous physical activity.