An epileptic seizure is a burst of uncontrolled electrical activity in the brain that temporarily disrupts how nerve cells communicate. This can affect how you move, feel, think, or behave, lasting anywhere from a few seconds to several minutes. Around 4 to 10 out of every 1,000 people worldwide have active epilepsy, and roughly 5 million new cases are diagnosed each year.
What Happens in the Brain
Your brain runs on electrical signals. Billions of nerve cells fire in coordinated patterns to control everything from muscle movement to thought. During an epileptic seizure, groups of neurons begin firing in abnormal, disorganized bursts. This isn’t simply a matter of the brain being “too active.” Research from Harvard’s Massachusetts General Hospital has shown that seizures arise from complex interactions between different populations of brain cells, both the ones that excite activity and the ones that normally keep it in check. When that balance breaks down, the result is a seizure.
Where and how widely this disruption spreads determines what the seizure looks and feels like. A small cluster of misfiring neurons on one side of the brain might cause a twitch in your hand. A widespread disruption across both sides can cause you to lose consciousness and fall to the ground.
Types of Seizures
Seizures fall into two main categories based on where the abnormal activity starts.
Focal Seizures
Focal seizures begin on one side of the brain. They come in two forms. In a focal aware seizure, you stay conscious the entire time. You might feel a sudden wave of déjà vu, a strange sensation in your stomach, or notice unusual movements on one side of your body. Many people can talk through these episodes and remember them afterward.
Focal impaired awareness seizures are different. You lose awareness of your surroundings and may look confused or dazed. People in this state often pick at their clothes, smack their lips, or stare blankly. They typically can’t respond to questions or follow directions for several minutes. These seizures are sometimes mistaken for daydreaming or intoxication by bystanders.
Generalized Seizures
Generalized seizures begin (or appear to begin) on both sides of the brain at once and usually cause a loss of consciousness. The most recognized type is the tonic-clonic seizure, where muscles first stiffen (the tonic phase) and then begin rhythmic jerking (the clonic phase). A person may cry out, fall to the ground, and have visible muscle spasms. These are the seizures most people picture when they hear the word “epilepsy.”
But generalized seizures also include subtler forms. Absence seizures cause brief lapses in consciousness, often lasting just a few seconds. A person might stare into space, blink rapidly, or make small chewing motions before snapping back to normal. These are especially common in children and can happen dozens of times a day without anyone noticing. Other generalized types include myoclonic seizures (sudden, lightning-quick jerks), atonic seizures (a sudden loss of muscle tone that can cause someone to collapse), and tonic seizures (muscles going rigid without the jerking phase).
The Four Phases of a Seizure
Seizures don’t just switch on and off. They tend to unfold in distinct stages, though not every person experiences all four.
The prodrome can begin hours or even days before a seizure. It’s not the seizure itself but a shift in mood, energy, or behavior that some people learn to recognize as a warning sign. The aura is the true beginning of the seizure, often involving unusual sensations like a rising feeling in the stomach, a strange smell, or visual disturbances. Many people describe the aura as a brief “alert” that something is about to happen. The ictus is the seizure event itself, the period of active abnormal brain activity with its visible symptoms. Finally, the postictal phase is the recovery period afterward. Depending on the type and severity of the seizure, recovery can take minutes to hours. Confusion, fatigue, headache, and difficulty speaking are all common during this time.
Common Triggers
For people with epilepsy, seizures don’t always strike at random. Many people identify consistent triggers that make a seizure more likely. The most commonly reported ones include lack of sleep, illness (with or without fever), stress, flashing lights or visual patterns, alcohol use or withdrawal, hormonal changes tied to the menstrual cycle, missed medications, and going too long without eating.
Some people have what’s called reflex epilepsy, where seizures are reliably triggered by a specific stimulus. Photosensitive epilepsy, in which flashing lights provoke seizures, is the best-known example. But seizures can also be triggered by reading, certain sounds, or other highly specific situations. Tracking personal triggers through a seizure diary is one of the most practical tools for reducing seizure frequency.
How Epilepsy Is Diagnosed
A single seizure doesn’t automatically mean you have epilepsy. The International League Against Epilepsy defines the condition as having at least two unprovoked seizures more than 24 hours apart. A diagnosis can also follow a single unprovoked seizure if testing shows at least a 60% chance of another seizure within the next 10 years, or if a recognized epilepsy syndrome is identified.
The primary diagnostic tool is the electroencephalogram, or EEG. Small metal discs placed on the scalp record the brain’s electrical patterns, and people with epilepsy typically show characteristic changes in their brainwave activity. For seizures that are hard to catch in a standard EEG session, video EEG monitoring over longer periods can be especially useful. This is particularly helpful for subtle seizures that are hard to spot visually, or for seizures that happen during sleep. Brain imaging with MRI is also commonly used to check for structural abnormalities like scar tissue, tumors, or developmental differences that could be causing the seizures.
Treatment and Seizure Control
Medication is the first-line treatment for epilepsy, and the results are better than many people expect. In clinical trials of adults with focal seizures, roughly 70 to 80% of patients achieved seizure freedom within six months on their initial medication. The specific drug a doctor prescribes depends on the seizure type, since different medications work better for different forms of epilepsy. Children with absence seizures, for instance, respond best to different medications than adults with focal seizures.
Not everyone responds to the first drug tried. Some people need to try two or three medications, or a combination, before finding what works. For those whose seizures don’t respond to medication at all, options include surgery to remove the area of brain tissue where seizures originate, nerve stimulation devices, and specialized diets. The goal of treatment is always the same: eliminate seizures, or reduce them as much as possible, with the fewest side effects.
What to Do if Someone Has a Seizure
If you see someone having a seizure, the most important things are to stay calm and keep them safe. Move away anything nearby that could injure them. If they’re lying down, gently roll them onto their side with their mouth pointing toward the ground to keep their airway clear. Place something soft under their head. Loosen anything around their neck that might restrict breathing. Time the seizure from the start.
Never put anything in their mouth, and don’t try to hold them down or restrain their movements. Most seizures end on their own within a few minutes. Once the person is alert, help them sit somewhere safe, explain calmly what happened, and offer to help them get home.
Call 911 if the seizure lasts longer than five minutes, if a second seizure follows closely after the first, if the person has trouble breathing or doesn’t wake up afterward, if they were injured during the seizure, or if the seizure occurred in water. You should also call for help if it’s a person’s first seizure, if they’re pregnant, or if they have diabetes and lose consciousness.