What Are Seizures?

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When people hear the word seizure, they usually imagine someone who has collapsed and is in the throes of painful convulsions. While it's true that some having a seizure will have this experience, that's not always the case.

It's also a common misconception that having a seizure means someone has epilepsy. While seizures may indicate an epilepsy disorder, they can also be caused by a myriad of other things, such as alcohol withdrawal or low blood sugar.

If you (or someone you know) suddenly has a seizure but has never had one before, it's important to get medical help right away. Your healthcare provider will need to figure out what caused the seizure and whether you're likely to have more. Then your healthcare provider can begin exploring if and what treatment (usually one or more anti-seizure medications) is necessary.

Types of Seizures

Broadly speaking, there are three categories of seizures:

  • Generalized onset seizures: These affect both sides of the brain at once and can include tonic-clonic, absence, and atonic seizures.
  • Focal onset awareness seizures: This type typically affects one side of the brain; the person remains fully awake and aware.
  • Focal onset impaired awareness seizures: These also affect one side of the brain, but can causes gaps in consciousness.

Each of these categories includes several subtypes. While someone with epilepsy may experience only one type of seizure, others may be affected by several. In those cases, the person may require different forms of treatment to control their seizures.

There are also nonepileptic seizures or pseudoseizures. These clinically resemble seizures but are not caused by abnormal electrical activity in the brain. Rather, they're secondary to stress or psychological issues in certain individuals.

Seizure Symptoms

Symptoms of seizures vary greatly depending on their type. Some forms are very apparent, while others may occur without you even knowing what's going on.

  • A classic tonic-clonic seizure is a type most people recognize. Formerly called a grand mal seizure, the person's entire body goes stiff and does a lot of jerking.
  • By contrast, an absence seizure may cause a person to suddenly "blank out" for a moment, then return to full consciousness. (These used to be referred to as petit mal seizures.)
  • With atonic seizure, a body part suddenly goes limp or the head drops for several seconds.
  • In the case of focal onset seizures, patients can experience changes in smell, taste, vision, or dizziness, or tingling or jerking of a body part. These symptoms may or may not be associated with an impaired level of consciousness, staring into space, and repetitive movements such as chewing, hand rubbing, or walking in circles.

Often, symptoms persist for a few hours or even days after a seizure. The longer and more intense the seizure, the longer the recovery tends to take.


While epilepsy is one possible cause of seizures, the two are not the same.

  • A transient event caused by excessive or non-synchronous brain activity that can be provoked or unprovoked

  • A medical condition that's characterized by two or more seizures and has many potential causes, from traumatic brain injury to cerebral palsy

There are several conditions that commonly cause seizures, including acute head trauma, fever, stroke, and others.


A very high fever can provoke seizures in some predisposed young children and babies. These types of seizures are called febrile seizures and require prompt medical attention.

Acute Head Trauma

Bleeding and scars inside the brain from head trauma can interfere with the normal activity in the brain and cause seizures.


Alcohol withdrawal—the sudden discontinuation of alcohol after heavy use—can cause seizures, as can the withdrawal or use of certain illicit drugs.

Metabolic Abnormalities

Liver or kidney failure or electrolyte abnormalities (e.g., low sodium) associated with these organ failures can lead to seizures. An abnormally low blood sugar level can also result in seizures.


Strokes cause tissue damage in small or large areas of the brain, and this damage may cause seizures.

Strokes occurring in certain areas of the brain (for example, the temporal lobe) are more likely to cause a seizure disorder than in other areas, such as the brainstem.

Brain Hemorrhage

Brain hemorrhage, which is bleeding in or around the brain, can irritate brain tissue, resulting in seizures.

Strokes that cause brain bleeding (called hemorrhagic strokes) are more likely to cause seizures than ischemic strokes (those due to a lack of blood flow).


An infection of the meninges (the protective membranes that surround the brain), may disrupt brain activity and cause seizures. Luckily, most seizures associated with meningitis resolve once the underlying infection is treated.

Encephalitis/Brain Abscess 

Encephalitis (brain inflammation) and brain abscesses (a collection of pus in the brain) are serious, albeit uncommon, conditions that may produce immediate seizures, as well as lasting epilepsy.

Brain Tumors

Brain tumors are collections of cancer cells that either start in the brain or somewhere else in the body, but then spread to the brain (called metastasis). Brain tumors may cause swelling and pressure, disrupting the brain's normal electrical activity and resulting in seizures.

epilepsy diagnosis
Illustration by Verywell


If you have a seizure, your healthcare provider will likely order a variety of tests and scans to figure out why.

These tests may include:

You should also expect a physical and neurological exam. Try to be prepared to give a medical and family history as well. Be as detailed as you can when it comes to sharing any details about your seizure(s).


More than 25 anti-seizure drugs (called anticonvulsants) are approved by the U.S. Food and Drug Administration (FDA). Research suggests that 70% of people with epilepsy can have their seizures completely controlled by using one or more of these medications.

Other epilepsy treatment options include surgeries, implants, and a strict ketogenic diet.

However, if you have a seizure that's caused by something other than epilepsy, you likely won't need these options. Instead, your healthcare provider will recommend a treatment that's appropriate given the underlying cause in your case, whether it be a fever, an electrolyte imbalance, abnormal blood sugar, and so on.

One major exception is a brain tumor. The disease itself and brain surgery to remove tumors can lead to recurrent seizures, which may require anti-seizure drugs to control.


Preventing seizures, if possible, is essential to avoiding dangerous outcomes like falls or car accidents. There are two main approaches to preventing seizures—medication and trigger avoidance.


Some of the same medications used to treat seizures are also used to prevent them. If your healthcare provider prescribes one or more anti-seizure drugs, be sure to take them as directed, right on schedule. This is the best way to maintain an even level of the drug(s) in your body.

If you cannot tolerate your anti-seizure medication due to side effects, speak to your healthcare provider right away. Do not stop taking your medication on your own, as this can provoke seizures. Instead, your healthcare provider may advise you to slowly taper off of the medication or replace it with another one.

Trigger Avoidance

When seizure triggers are at play and are known, working to avoid them can be very helpful.

Some potential triggers of seizures include:

  • Alcohol intake
  • Sleep deprivation
  • Flashing lights
  • Stress
  • Weather changes
  • Certain odors


Even if your healthcare provider believes your seizure was an isolated event, you may still worry about having another one. If you need help dealing with that fear, you may benefit from mental health counseling. Otherwise, you shouldn't need to make changes to your life based on having a single seizure. Be sure, however, to follow up with your healthcare provider as recommended.

If you're diagnosed with epilepsy or something else that may cause recurrent seizures, you may need to make some lifestyle changes and learn to cope with your diagnosis. Taking measures to ensure your safety when you have a seizure is also beneficial.

The important thing to remember in case you or someone you know has a seizure is that it's a serious medical event that requires emergency care.

That said, please keep in mind that seizures are more common than most people realize, and healthcare providers and nurses know how to deal with them—both in an emergency setting and short or long-term treatment is required.

15 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Reza Shouri, MD
Reza Shouri, MD, is an epilepsy physician and researcher published in the Journal of Neurology. Dr. Shouri has always been fascinated with the structure and function of the human brain.