Fainting vs. Seizure: How to Tell the Difference

Dehydration, stress or exhaustion can cause a person to temporarily pass out. But an unprovoked loss in consciousness could mean you’ve either had a seizure or syncope, the medical name for fainting.

It’s important to seek medical attention the first time a person passes out with no explanation, and some situations require an immediate trip to the emergency room. You should call 911 after a person passes out and:

• They’ve suffered an injury.
• They’ve remained unconscious for longer than a minute.
• They lost consciousness in water or seem to stop breathing while unconscious.
• They are pregnant or have diabetes, and this is the first time they’ve lost consciousness.

To make a diagnosis, doctors will ask the person who lost consciousness—and anyone around them at the time—for a recollection of what happened.

“It’s helpful to know what happened immediately before or after the event, from either the patient or a bystander,” said Rohit Gummi, MD, a neurologist in the Cedars-Sinai Epilepsy Program. “This can help us differentiate between seizure and fainting.”

Fainting vs. Seizure: Symptoms, Key Differences and When to Get Help

Syncope and seizure can both involve loss of consciousness. Fainting usually happens when blood flow to the brain briefly drops, while a seizure is caused by abnormal electrical activity in the brain.

Seizure Symptoms

• Abnormal sensations or behavior immediately before loss of consciousness
• Confusion or disorientation after regaining consciousness
• Loss of bladder or bowel control
• Tongue biting
• Convulsions
• Involuntary movements
• Lip smacking
• Drooling
• Random eye movements
• Staring into space

Fainting Symptoms

• Nausea or cold sweats immediately before loss of consciousness
• A return to normal cognition after regaining consciousness
• Loss of consciousness when changing positions, such as sitting to standing
• Jerking movements
• Tunnel or blurred vision
• Skin pallor
• Dizziness

Seizures

Why they happen: Seizures happen when there’s a disturbance in the normal electrical activity in the brain, said Lisa Bateman, MD, a neurologist and director of the Surgical Epilepsy Program.

One seizure doesn’t mean you have epilepsy—5% to 10% of people will have a seizure in their lifetime. A seizure can be a sign of imbalances in your body that doctors can treat, but it can also signify something more serious, such as a stroke, tumor or infection.

What they look like: Seizures can look different depending on which part of the brain is affected.

You may or may not lose consciousness. You might shake violently or stare into space, and you may not recognize your name.

And while the symptoms can last for a full minute or more, you’ll probably have no memory of the experience.

What you should do: If you see someone experiencing a seizure, get them to the floor if they aren’t already lying down, and move hard and sharp objects away from them.

Don’t put anything in their mouth.

Don’t attempt to restrain them or hold them down. Instead, wait for the seizure to end.

After experiencing their first seizure, a person should see a doctor as soon as possible. Getting checked out within 72 hours of the seizure can help doctors make a thorough diagnosis. Establishing contact with a provider also ensures you can make a follow-up appointment if you experience another event.

“Even if you recover from a seizure without injury, you may have another one in the future in a more high-risk situation,” Gummi said. “The good news is there are a lot of treatments to mitigate the risk of recurrent seizures. Getting ahead of it can help prevent injury or worse.”

Fainting

Why it happens: Sudden loss of consciousness, or syncope, happens when there isn’t sufficient blood flow to the brain—and the experience is fairly common. About one-third of all people will faint at least once during their lifetime.

Syncope can happen as a random, isolated event, or it can happen frequently over a period of time.

In younger people, the causes for fainting tend to be benign. For example, maybe they haven’t eaten or they’re dehydrated. In older people, fainting is sometimes a sign of cardiac issues, such as atrial fibrillation.

What you should do: While you may recover quickly and fully from a fainting spell, you should always tell your doctor about the episode.

“Fainting can be attributable to less worrisome issues, but a sudden loss of consciousness for any reason signifies it’s a blood flow or electrical issue, and it should be checked out,” Bateman said. “It could be a sign of an underlying heart problem, so it’s important to visit a health professional for a proper evaluation and treatment plan.”

If you feel faint while standing, lie down. If you’re sitting, place your head between your knees.

If you see someone else faint, place the person face up and raise their legs above their heart level. If the person doesn’t “come to” within one minute, call 911.

Get Evaluated to Prevent Future Harm

Determining the underlying cause of fainting or a seizure usually requires a visit to your doctor, who will likely do cardiac and neurological tests.

“People tend to minimize these health events, but doctors would rather do a full evaluation and reassure you that everything is fine than have a potentially serious issue go unnoticed,” said Bateman.

For patients who have been diagnosed with a first-time seizure, Cedars-Sinai’s new-onset seizure clinic offers quick evaluation while you concurrently establish long-term care.

“After a first-time seizure, it can be distressing to wait to see a doctor. So, at our clinic, we can evaluate you quickly and judge your risk while you wait to get established with a neurologist,” Gummi said. “It’s a very scary thing when a seizure happens to anyone, and we want to get you answers.”