Types of Seizures

Medically Reviewed by Jabeen Begum, MD on July 25, 2024
Written by Heather Rose Artushin, LISW
6 min read

Normally, your brain sends signals through your nervous system in a predictable, organized way. But sometimes, these signals get mixed up and cause a seizure. You might experience a seizure as a sudden change in how your brain works. It's like a burst of electrical activity that disrupts your normal brain function. This can cause you to feel confused for a short time, have uncontrollable movements, stare blankly, or even lose consciousness altogether. Seizures can happen for many reasons, and they can be mild or severe.

There are three main types of seizures:

Focal seizures. These affect only one side of your brain and body. The symptoms depend on the area of the brain where the seizure happens. As the seizure gets more intense, it can start to affect other parts of your brain.

The most common type of seizures, focal seizures are named based on the specific part of the brain where they happen. They can cause physical and emotional effects and make you feel, see, or hear things that aren’t there. About 60% of people with epilepsy have this type of seizure, which is sometimes called a partial seizure. Sometimes, the symptoms of a focal seizure can be mistaken for signs of mental illness or another kind of nerve disorder.

Generalized seizures. These happen when nerve cells on both sides of your brain misfire. They can cause a variety of symptoms such as muscle stiffening, falls, and jerking movements. Often, they can cause you to lose consciousness.

Unknown-onset seizures. When the beginning of a seizure is not known, it is called an unknown-onset seizure. This diagnosis is often given if no one is around to witness your symptoms when your seizure starts. Later, after more information is collected, your diagnosis might be changed to a specific type of seizure.

What is epilepsy?

Epilepsy is a brain disorder that happens when certain nerve cells in your brain misfire. It is the most common cause of recurring seizures. They can affect your behavior or the way you see things around you for a short time. There are about a dozen types of epilepsy. Understanding the kind of seizures you experience helps your doctor determine the type of epilepsy you have.

Other causes of seizures 

Epilepsy isn’t the only cause of seizures. You can also have a seizure from:

There are six kinds of generalized seizures:

Clonic seizures

In a clonic seizure, your muscles have spasms, which often make your face, neck, and arm muscles jerk rhythmically, on one or both sides of the body. They may last a few seconds to several minutes. This kind of seizure is rare, and most often occurs in infants.

Tonic seizures

Tonic seizures cause the muscles in your arms, legs, or trunk to tense up. These usually last less than 20 seconds and often happen when you’re asleep. But if you’re standing up at the time, you can lose your balance and fall. These are more common in people who have a rare kind of epilepsy known as Lennox-Gastaut syndrome, though people with other types can have them too.

Tonic-clonic seizures

These may begin with an aura — an abnormal sensation or feeling — marked by a particular smell, a feeling of vertigo, nausea, or anxiety. They involve a tonic phase and then a clonic phase. When you have this type, you lose consciousness and your body stiffens, and then it jerks and shakes. Sometimes, as the seizure ends and your body relaxes, you lose control of your bladder or bowels. They usually last 1 to 3 minutes; if they go on longer, someone should call 911. Tonic-clonic seizures were originally called “grand mal” seizures.

Atonic seizures

In this kind of seizure, your muscles suddenly go limp, and your head may lean forward. If you’re holding something, you might drop it, and if you’re standing, you might fall. These usually last less than 15 seconds, but some people have several in a row.

People who have Lennox-Gastaut syndrome and another kind of epilepsy called Dravet syndrome are more likely to have this kind of seizure.

Myoclonic seizures

Myoclonic seizures cause your muscles to suddenly jerk as if you’ve been shocked. They may start in the same part of the brain as an atonic seizure, and some people have both myoclonic and atonic seizures. Infantile spasms, which are a kind of myoclonic seizure, occur in babies between the ages of 3 and 12 months. They are most common when the baby is waking up.

Absence seizures

This type of seizure causes you to lose consciousness and seem disconnected from others around you. You may stare blankly into space, and your eyes might roll back in your head. They usually last only a few seconds, and you may not remember having one. They’re most common in children under 14. Absence seizures used to be called petit mal seizures.

Doctors break these into two groups:

Focal onset aware seizures. These change how your senses read the world around you. They can make you smell or taste something strange and may make your fingers, arms, or legs twitch. You also might see flashes of light or feel dizzy. You’re not likely to lose consciousness, but you might feel sweaty or nauseated. You might be able to talk during this kind of seizure and remember the seizure after.

Focal impaired awareness seizures. These usually happen in the part of your brain that controls emotion and memory. You may lose consciousness but still look like you’re awake, or you may do things such as gag, smack your lips, laugh, or cry. It may take several minutes for you to come out of a complex focal seizure.

If someone around you has a seizure, roll them onto their side and place something soft under their head, making sure nothing is in their mouth. Speak to them in a steady, reassuring tone of voice. If they’ve never had a seizure before, the seizure lasts longer than 5 minutes, or if they have trouble breathing or waking up after the seizure, call 911. Stay with them until medical help arrives. You can time the seizure, and carefully observe the details of what happens, to share with the physician.

If you have a seizure, stay calm. Do your best to prevent injury by moving away from furniture with sharp corners, swimming pools, and other potential hazards. If you have recurring epileptic seizures, wear a medical alert bracelet, share seizure first-aid information with your colleagues and loved ones, and have prescribed rescue medication handy to stop a seizure.

If you or someone you love experiences a seizure, it is important to stay calm, call for medical help when necessary, and observe the characteristics of the seizure as closely as you can. Understanding the types of seizures can help you be prepared to prevent and manage seizures in the future. Ask your doctor for details regarding your medical treatment plan.

What are the most common triggers of a seizure?

Sleep deprivation, fever, substance use, stress, flashing lights, poor nutrition, hormonal changes, and not following medication protocols are some of the most common seizure triggers.

How can one manage or control seizures?

Follow up with your doctor regularly and take medications as prescribed. Avoid known triggers, and wear a medical bracelet if you get recurring seizures.

Is epilepsy the same as having seizures?

Epilepsy, a brain disorder, is the most common cause of repeated seizures. However, a single seizure can be caused by other factors such as brain tumors, substance use, traumatic brain injury, and severe infection, without the presence of epilepsy.