Epilepsy is the disorder defined by recurrent seizures. It affects more than 50 million people worldwide, making it one of the most common neurological conditions. While a single seizure doesn’t automatically mean epilepsy, the diagnosis typically applies when a person has had at least two unprovoked seizures more than 24 hours apart, or when a single seizure carries a 60% or greater chance of another occurring within the next 10 years.
What Makes It Epilepsy vs. a Single Seizure
Not every seizure means a person has epilepsy. Seizures can be provoked by temporary conditions: dangerously low blood sugar, severe dehydration, liver or kidney failure, electrolyte imbalances like very low sodium, alcohol withdrawal, cocaine use, or even extreme sleep deprivation. These are called acute symptomatic seizures, and once the underlying cause is treated, they typically don’t recur. Epilepsy, by contrast, involves seizures that arise from the brain itself without an obvious outside trigger.
A doctor will also consider whether the pattern fits a recognized epilepsy syndrome, which is a specific combination of seizure types, age of onset, and brain wave patterns that tends to follow a predictable course. Some syndromes begin in childhood and resolve by adulthood, while others are lifelong.
Types of Seizures
Seizures fall into three broad categories based on where they start in the brain.
Focal seizures begin in one specific area. They can look very different depending on which part of the brain is involved. Some cause twitching in one hand or side of the face. Others produce unusual sensations, emotional shifts, or repetitive movements like lip-smacking or hand-rubbing (called automatisms). A key distinction is whether awareness stays intact or becomes impaired. If at any point during the seizure a person seems confused or unresponsive, it’s classified as a focal impaired awareness seizure. Focal seizures can also spread to both sides of the brain and develop into full-body convulsions.
Generalized seizures engage networks on both sides of the brain from the start. The most recognized type is the tonic-clonic seizure (formerly called grand mal), where the body stiffens and then jerks rhythmically. But generalized seizures also include absence seizures, which look like brief staring spells lasting a few seconds, often mistaken for daydreaming in children. Other subtypes involve sudden muscle jerks (myoclonic), sudden loss of muscle tone causing a person to drop (atonic), or combinations of these patterns.
Unknown onset seizures are those where the beginning wasn’t observed or isn’t clear from testing. They can still be described by their visible features, such as convulsive movements or behavior arrest.
Common Triggers for People With Epilepsy
Triggers don’t cause epilepsy, but they can lower the threshold for a seizure in someone who already has it. Most people with epilepsy don’t have a single reliable trigger that always produces a seizure, but certain factors come up repeatedly: missed doses of medication, lack of sleep, high stress, dehydration, flashing or strobing lights, hormonal changes during the menstrual cycle, and illicit drug use. Keeping a seizure journal that tracks timing, duration, sleep quality, stress levels, and missed medications can help reveal individual patterns over time.
How Epilepsy Is Diagnosed
The cornerstone test is an electroencephalogram (EEG), which measures electrical activity in the brain over minutes to hours. It can reveal abnormal patterns that point to the type of seizure and where in the brain it originates. In some cases, doctors use prolonged video-EEG monitoring, where a camera records the person continuously alongside brain wave data so that any seizure can be analyzed in real time.
Brain imaging plays a complementary role. An MRI can reveal structural problems like scars, tumors, or developmental abnormalities that may be producing seizures. A PET scan shows areas of altered metabolism in the brain between seizures, which helps pinpoint the seizure focus. Functional MRI can map where critical functions like speech and memory are located, which becomes especially important if surgery is being considered.
Seizures That Aren’t Epilepsy
Some people experience episodes that look like seizures but don’t involve abnormal electrical activity in the brain. These are called psychogenic nonepileptic seizures (PNES), and they’re a physical reaction of the nervous system to psychological distress rather than a brain malfunction. Common underlying conditions include PTSD, anxiety disorders with panic attacks, dissociative disorders, and depression. An EEG recorded during an episode will show normal brain activity, which is the definitive way to distinguish PNES from epileptic seizures. This distinction matters because anti-seizure medications won’t help PNES, and the treatment path is different.
Febrile seizures are another non-epileptic type, occurring in otherwise healthy children between 6 months and 5 years old, with the highest risk between ages 1 and 3. These seizures are triggered by fever and, while alarming to watch, are generally not harmful. Children who have their first febrile seizure before 18 months, who have a family history of febrile seizures, or who seized at a relatively low fever are more likely to have another episode. Having febrile seizures does not mean a child will develop epilepsy.
Treatment and Seizure Control
Anti-seizure medications are the first line of treatment. In a long-running study of nearly 1,800 people with newly diagnosed epilepsy, about 46% became seizure-free for at least a year on their first medication. For those whose first medication failed, a second regimen brought an additional 12% to seizure freedom, and a third added roughly another 4%. Altogether, the majority of people with epilepsy can achieve meaningful seizure control with medication, though the chances drop significantly after the first drug doesn’t work.
For people whose seizures don’t respond to two or more medications (a situation called drug-resistant epilepsy), other options exist. Surgery to remove or disconnect the seizure focus is an option when imaging clearly identifies where seizures originate. Nerve stimulation devices and specialized diets like the ketogenic diet are also used, particularly in children. The specific path depends on the seizure type, where it starts, and how it responds to initial treatment.
What to Do if Someone Has a Seizure
If you witness a convulsive seizure, stay calm and stay with the person. Move nearby objects that could cause injury. If they’re on the ground, turn them gently onto their side with their mouth pointing downward to keep the airway clear. Place something soft under their head. Loosen anything tight around the neck. Remove their glasses if they’re wearing them. Time the seizure from the start.
Call 911 if the seizure lasts longer than five minutes, if a second seizure follows closely, if the person has trouble breathing or waking afterward, if they’re injured, if the seizure happens in water, or if it’s their first seizure. You should also call if the person is pregnant or has diabetes and loses consciousness. Never put anything in their mouth or try to restrain them. Most seizures end on their own within a few minutes, and once the person is alert, calmly explain what happened and help them get to a safe place to recover.