Seizure vs. fainting: differences and similarities

  • October 26, 2023
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A man clenching his temple while sitting down

When doctors are trying to diagnose illnesses, one of the biggest challenges is that different conditions can have very similar symptoms. Take fainting and seizures, for example. With both conditions, people’s muscles may go limp, they can lose consciousness, and they might fall over. With both seizures and fainting, people may twitch and jerk too, before waking up. 

Let’s compare fainting vs. seizures, and see how these two conditions differ from each other. 

Fainting and seizures: what are they?

Before we compare fainting vs. seizures, it’s helpful to understand what each event actually is. 

Fainting, which is also known as ‘syncope’, is when there isn’t enough blood getting to a person’s brain. They lose consciousness and fall down. About a third of people will experience syncope at least once in their lives. 

Fainting is caused by many things, but the most common is a fall in blood pressure. It may also happen because of cardiac arrhythmias (irregular heartbeat), problems with blood flow to the brain, plus things like hot weather, standing too long, or feeling stressed and tired. 

Seizures are when there is a sudden discharge of electrical signals in the brain. Seizures can cause many different symptoms, which can include falling over, losing consciousness, arm and leg movements, or shouting out. One person in ten will have a seizure in their lives. And one person in 26 will develop epilepsy (which is when you have two or more unprovoked seizures). 

Epilepsy may be caused by a genetic condition, brain damage, or an unknown cause. Provoked seizures (which aren’t epileptic) may be caused by things like sodium deficiency, alcohol withdrawal, or brain infection, among other things. 

Keep learning: Sleep apnea and epilepsy

Seizures vs. fainting: key differences

To understand the difference between fainting and seizures, the following table can help. 

Underlying causes:

- Seizure

A sudden discharge of electrical activity in the brain. 

- Fainting (syncope)

Not enough blood reaching the brain. Often due to a loss of blood pressure. 

Main symptoms

- Seizure

Many different symptoms, but often includes convulsions, repetitive movements, jerks and twitches, shouting out. 

- Fainting (syncope)

Losing consciousness. 

Electroencephalogram (EEG) test 

- Seizure

May show ‘epileptiform’ brain activity. 

- Fainting (syncope)

Shows normal brain activity. 


- Seizure

If epilepsy is diagnosed, usually requires treatment for many years. 

- Fainting (syncope)

Depends on the cause of syncope. For many cases, small lifestyle changes are enough, but can also suggest the person has a heart condition which needs treatment. 

To make things confusing, there is one kind of epileptic seizure that is triggered by fainting. This is called anoxic-epileptic seizure, but it appears to be very rare

Fainting vs. seizures: similarities

Fainting and seizures can easily be confused because they sometimes share very similar symptoms:

  • Convulsive syncope: It is estimated that around 12% of people who faint will also have involuntary jerks while they are passed out. To the untrained eye, this can look like an epileptic seizure. 
  • Unpredictable nature: Both syncope and seizures happen at unpredictable moments. 
  • Loss of muscle tone: Most of the time, our muscles are able to hold us up. But in fainting and some types of seizure, our muscles lose this ability and people fall over (if they were standing). 

While you should always get your diagnosis from a doctor, the 10/20 rule can help medical professionals estimate if someone is having convulsive syncope, or epileptic seizures. If the person falls over and jerks 10 times or less, it’s more likely to be fainting. If they jerk 20 times or more, it’s more likely to be a seizure. 

Suggested: What are nonepileptic seizures?

Seizures that look like fainting

Many seizures look very different to fainting. However, there are two types of seizure that can easily be confused with syncope. In tonic seizures, your muscles suddenly go stiff, which means you may lose your balance and fall down. In atonic seizures your muscles lose their ‘tone’ and you collapse. In both types, you usually lose consciousness. 

Suggested: Panic attacks vs. seizures

Getting help for fainting and seizures

If someone has started losing consciousness and falling over, then it is vital to seek medical treatment as soon as possible. 

  • If it’s fainting: Most of the time, fainting doesn’t mean there’s anything seriously wrong with you. But it could be a sign of an underlying condition - including heart problems. Your physician will do various tests (such as checking your blood pressure) to learn more about what may be causing your fainting. 
  • If it’s seizures: If you are falling over because you’re having epileptic seizures, getting treatment is really important too. Your doctor will do epilepsy tests, including blood tests, EEG and MRI to identify the cause of the seizures. 

By getting help for fainting and seizures, you can get to the bottom of these events, and receive the right treatment for your situation.

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