Seizures: Causes, Symptoms, and Treatment

Medically Reviewed by Jabeen Begum, MD on December 04, 2023
9 min read

A seizure is abnormal electrical activity in the brain that happens quickly. It may go nearly unnoticed. In serious cases, it may cause unconsciousness and convulsions, when your body shakes uncontrollably.

Seizures usually come on suddenly. How long and serious they are can vary. A seizure can happen to you just once or over and over. If they keep coming back, that's epilepsy, or a seizure disorder. Less than 1 in 10 people who have a seizure get epilepsy.

What happens during a seizure?

Inside your brain are billions of cells called neurons. Their job is to send and receive chemical and electrical signals to each other. It's an important job — because of neurons, you're able to move, think, and speak.

But if this delicate system hits a glitch, neurons will fire off signals by mistake. That causes a seizure. The more neurons that are affected, the more severe the seizure. 

During a seizure,  you'll likely pass out. If someone were to test a sample of your blood, they'd also see changes in different chemicals. Your body is doing the best it can to manage the situation while your brain is temporarily "offline."

You can have two types of seizures. 

Provoked seizure: This type is triggered by something that irritates your brain. For instance, an infection, high or low blood sugar,  a reaction to a drug, alcohol withdrawal, not getting enough sleep, and bright flashing lights can cause seizures. 

Unprovoked seizure: You can also have a seizure for reasons that are unclear.  Doctors call this an unprovoked seizure.

If you have two or more unprovoked seizures, you may be diagnosed with epilepsy. This brain condition sometimes runs in families. But it can also be caused by a head trauma, infection, tumor, or injury that happened before birth. Some developmental issues, like autism, can also raise your risk of epilepsy. 

Psychogenic nonepilepsy seizure (PNES) is a condition that involves attacks like the seizures caused by epilepsy. But if you have PNES, your seizures are caused by intense emotional trauma or stress instead of abnormal brain activity. It's possible to have both PNES and epilepsy.

Generalized seizures

Generalized seizures involve your entire brain from the start. Common subtypes include:

  • Tonic-clonic ("grand mal"). This is the most common subtype. Your arms and legs get stiff, and you may stop breathing for a bit. Then your limbs will jerk around. Your head will move about, as well.
  • Atonic. You briefly lose all muscle strength when you have an atonic seizure, or what's sometimes called a "drop attack." Although they usually last less than 15 seconds, you risk harming yourself. For instance, if you're walking downstairs when one happens, you could fall down.
  • Clonic. Babies are most likely to have clonic seizures, although they're very rare. They cause jerky movements on both sides of the body at the same time.
  • Myoclonic. Unlike some other subtypes, you're usually awake and alert during a myoclonic seizure. You'll notice jerky movements in one or more muscle group. It could involve just your upper body, or your entire body.
  • Tonic. If you have a tonic seizure, your body, arms, and legs will become very stiff and hard to move. They happen most often during sleep and may only last 20 seconds.
  • Absence seizures. You lose awareness briefly when you have one of these. Children get them more often than adults. Typically, they last only a few seconds.
  • Febrile seizures. These are convulsions a child may have from a high fever caused by an infection. They can last a few minutes but are usually harmless.
  • Infantile spasms. These usually stop by age 4. A child's body gets stiff suddenly and their head goes forward. Many kids who have these get epilepsy later in life.

Focal seizures

There are two types:

  • Focal onset aware seizure. Also known as a simple partial seizure or simple focal seizure, you'll remain awake and aware while it happens. This type is often very brief (usually less than 2 minutes). You may or may not be able to respond to people while it's happening.
  • Focal onset impaired awareness seizures can cause unconsciousness. You may also do things without knowing it, like lip smacking, chewing, moving your legs, or thrusting your pelvis. This type can also be called a complex focal seizure or a complex partial seizure.

Seizures can happen with no explanation, but many conditions and events are known to bring them on, including:

  • Stroke
  • Cancer
  • Brain tumors
  • Head injuries
  • Electrolyte imbalance (too high or too low levels of minerals in your blood)
  • Very low blood sugar
  • Repeating sounds or flashing lights, like you might find in video games
  • Some medications, like antipsychotics and some asthma drugs
  • Withdrawal or overdose from medications like benzodiazepines, narcotics, or alcohol
  • Narcotics such as cocaine and heroin
  • Brain infections like meningitis
  • A high fever
  • COVID-19
  • Developmental brain issues
  • Hormone changes
  • Toxins
  • Eclampsia (very high blood pressure during pregnancy)
  • Degenerative brain diseases (like dementia)

Seizures have different symptoms based on the type you have and if the seizure is about to start, is currently happening, or recently ended.

It's important to track your symptoms so you can tell your doctor. These details, even if they seem small or embarrassing, can help figure out the type of seizure you had and how to try to prevent it from happening again.

Although a seizure may feel like it comes on all of a sudden, it happens in stages.

Beginning phase (Prodrome)

Hours or even days before a seizure starts, you may start to have symptoms. Some common signs are:

  • Trouble sleeping
  • Mood changes
  • Feeling anxious
  • Trouble paying attention
  • Feeling lightheaded 

Early ictal phase

An aurais like a warning sign from your brain that a seizure has begun. You could notice:

  • Odd smells, sounds, or tastes
  • Feeling dizzy
  • Changes in your eyesight (like flickering or blurry vision)
  • "Pins and needles" feelings in parts of your body
  • Arm or leg pain
  • Arm or leg twitching
  • Ringing or buzzing sounds
  • An out-of-body sensation
  • Hallucinations (seeing things that aren't there)
  • Feelings of intense fear or panic
  • Deja vu (a sense that something has happened before although it hasn't)
  • Jamais vu (feeling like you're seeing something familiar for the very first time)
  • Nausea (feeling sick to your stomach)
  • Headache

Not everyone who has a seizure will have an aura. And you can have an aura that won't progress into a more intense seizure.

Middle (ictal) phase

The period between your very first symptom and the end of a seizure is called the ictal stage. Its symptoms are what most people think of when they think of a seizure. They include:

  • Stiff arms and/or legs
  • Uncontrollable lip smacking or chewing
  • Vision changes and/or dilated pupils
  • Racing heart
  • Sweating
  • Finding it hard to breathe
  • Feeling confused or distracted
  • Hearing strange sounds
  • Flushed or pale skin
  • Drooling
  • Twitching
  • Tremors
  • Feeling unable to move or talk
  • Acting oddly (like taking off your clothes or suddenly running)
  • Incontinence (losing control of your pee or poop)

Ending (post-ictal) phase

You can recover right away from a seizure, or it may take days before you feel like yourself again. How long this phase lasts depends on the type of seizure you had and how severe it was. Among the symptoms you can have are:

  • Weakness in parts of your body
  • Soreness
  • Body aches
  • Low energy
  • Feeling sleepy
  • Increased thirst
  • High blood pressure
  • Headaches or migraines
  • Nausea
  • Feeling confused or forgetful
  • Feeling embarrassed, scared, or sad
  • Finding it hard to hold your pee or poop

Seizures are surprisingly common. According to the CDC, 1 in 10 people can have a seizure during their lifetime. Because of that, it's wise to know what to do if you see someone having a seizure.

  • Stay with the person. They may not know what's happening, so stay with them until they're fully awake again.
  • Help them to a safe place. Once the seizure is over, gently move them to a sitting position.
  • Offer comfort. Stay calm, and tell them in very simple terms what happened. 
  • Check for a medical ID. Look for a medical tag that lists any health conditions. If they're alert and can talk, you can also ask them.
  • Get them home. Call their emergency contact or offer to call a taxi or ride share so they can get home.

When to call the doctor

Although seizures are unsettling, they're not usually medical emergencies. But if one or more of these are true, call 911 right away.

  • The seizure happens in water.
  • The person has never had a seizure before.
  • They have a health condition (like pregnancy, heart disease, or diabetes).
  • The seizure lasts 5 minutes or longer.
  • They have trouble breathing or walking after the seizure.
  • Another seizure begins.

Your doctor will ask for details about your seizure and do a neurological exam. This will include asking questions about your emotional state and testing your motor skills and mental functioning. Then they may order one or more of the following tests:

  • Blood tests or a spinal tap to look for an infection
  • Electroencephalography (EEG) during which a technician will attach electrodes to your scalp to monitor the electrical activity inside it
  • An imaging test such as an MRI, CT, or PET scan to look for any problems in your brain 
  • Single-photon emission computed tomography (SPECT), which injects a tiny amount of radioactive substance into your vein to learn how blood flows through your brain during a seizure

If your seizures happen frequently, your doctor may give you a more involved test in which electrodes are inserted into your brain through small holes in your skull. 

It's possible to have only one seizure and not need treatment, but if your seizures continue, there are several ways your doctor may suggest treating them, including:

  • Medication. Anti-seizure medications can cause some serious side effects, so you and your doctor will consider all the options. You may need to try a few before you find one that's effective and least likely to cause side effects.
  • Surgery. If your seizures always come from the same place in your brain, it may be possible for a neurosurgeon to remove just that portion of your brain to stop the seizures. 
  • Vagus nerve stimulation. Your vagus nerve is the longest nerve in your skull, running all the way from your brain to your stomach. A specialist can implant a medical device under the skin of your chest that will send electrical signals along your vagus nerve to your brain and limit seizures. Usually, you still need to take medication. 
  • Responsive nerve stimulation. A device implanted into your brain spots and then stops seizures. 
  • Deep brain stimulation. Surgeons put devices into certain brain areas and then implant a pacemaker-like machine in your chest. It can send electrodes to those regions to prevent or stop seizure activity. 

To reduce the chance that you'll have a seizure, you can:

  • Talk to your doctor about following a ketogenic diet, which is high in fat and protein and very low in carbohydrates. It's been shown to be helpful in reducing how often you have seizures.
  • Get good sleep. Lack of rest can be a trigger for seizures.
  • Take any medications as directed. 
  • Try rescue medications. These don't take the place of daily medications and should only be used to help stop a seizure quickly in emergency situations. Depending on the circumstance, they can be taken several ways and include: 
    • Diazepam, given orally (if the person is awake) or as a nasal spray 
    • Lorazepam, given orally
    • Midazolam, given orally (if the person is awake) or as a nasal spray
  • Limit how much alcohol you drink.
  • Pay attention to things that trigger your seizures and try to avoid them. 
  • Wear a seizure alert device that can alert others when you're having a seizure. Although it can't prevent seizures from happening,  it can allow you to have more freedom and less worry.

A seizure is a sudden, uncontrolled burst of electrical activity in your brain. It can happen for many different reasons, from a head injury to not getting enough sleep. If you have one, it's important to follow up with your doctor so they can figure out the cause and try to prevent it from happening again.