These seizures can make person shake and jerk for up to three minutes, but recovery can take hours.

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When you think of a seizure, chances are a grand mal seizure is the first thing that comes to mind. It's the type of seizure that can cause a person to fall down, shake and jerk, and even lose consciousness.

But the term "grand mal seizure"—which technically means "big illness" in French—is actually an outdated one: In 2017, the International League Against Epilepsy (ILAE) came up with new ways to describe and classify seizures. As part of that, what was once known as a "grand mal seizure" is now called a "tonic-clonic seizure," according to the Epilepsy Foundation. ("Grand mal seizure" and "tonic-clonic seizure" will be used interchangeably throughout this article.)

Despite the new name, grand mal seizure is often the term people are most familiar with (some doctors even continue to use it in medical settings, especially if they don't specialize in seizures). Regardless of what you know them as—grand mal seizures or tonic-clonic seizures—here's what you need to know about them, including their main causes and how long they typically last.

What Is a Grand Mal Seizure? Here’s What to Know, According to Experts
Credit: Getty Images

What is a grand mal seizure—and what does one look like?

A grand mal seizure is an example of a generalized onset motor seizure, or a generalized tonic-clonic seizure, the Epilepsy Foundation says. This means that the seizure starts in both sides of the brain. In some cases, however, tonic-clonic seizures can start on just one side of the brain (aka, a focal seizure), before spreading to both sides. The Epilepsy Foundation specifically calls this type of seizure a bilateral tonic-clonic seizure.

Grand mal seizures typically have two phases, per the Epilepsy Foundation: a tonic (stiffening) phase, followed by a clonic (jerking) phase—that's what has given them their current, more up-to-date name.

  • Tonic phase: This phase comes first, and causes the muscles in a person's body to stiffen. In this phase, a person can lose consciousness and fall to the floor. They may also let out a cry or a groan, due to air being forced past their vocal cords; and they may bite their tongue or inside of their cheek.
  • Clonic phase: The tonic phase is followed by the clonic phase, which is when a person's arms and legs begin to jerk "rapidly and rhythmically." This bending and relaxing tends to happen at the elbow, knee, and hip joints. It can last for a few minutes, before slowly coming to a stop.

During a grand mal seizure, someone may also lose control of their bladder or bowels, per the Epilepsy Foundation—this happens when the body relaxes. If the person is having trouble breathing, they may also begin to take on a "dusky" or blue hue to their face.

Another common grand mal seizure symptom is an aura, according Johns Hopkins Medicine. This phenomenon, which generally happens just before the seizure, can include a range of abnormal sensations, like anxiety, nausea, and vertigo, and even smelling a particular odor. 

What causes a grand mal seizure?

Like all seizures, a grand mal or tonic-clonic seizure happens when there's a sudden surge of electrical activity in the brain. Usually, grand mal seizures are caused by epilepsy, per the Mayo Clinic. But grand mal seizures may also be caused by a medical problem, such as alcohol withdrawal, traumatic head injury, or an infection like meningitis. Other times still, the cause isn't known, and the seizure seems to happen at random. 

"We always try to figure out the cause, because it's more satisfying to know why someone is having seizures, of course," Vikram Rao, MD, PhD, an associate professor of neurology at the University of California, San Francisco, tells Health. "But in many cases, we actually never do. It's not at all uncommon for there to be no obvious explanation." 

How long does a grand mal seizure last?

A grand mal seizure usually lasts between one and three minutes, per the Epilepsy Foundation. After that, a person's consciousness can slowly return, but recovery after a grand mal seizure can take considerably longer. Many report feeling sleepy, confused, anxious, or agitated for hours after the fact. 

If a seizure goes on for longer than five minutes—or if a person has three seizures in a row without regaining consciousness between them—they need emergency medical attention. In this case, the person is experiencing something known as status epilepticus, of which there are two types: convulsive status epilepticus and non-convulsive status epilepticus, the Epilepsy Foundation says.

Though both types require medical treatment, nonconvulsive status epilepticus may be hard to recognize. In the case of convulsive status epilepticus, medical treatment must be started as soon as possible—typically through oxygen, intravenous fluids, medications, and continuous EEG (electroencephalogram) monitoring. Sometimes, people may even be put into a coma to get the seizures to stop.

Can you die from a grand mal seizure?

It's rare to die from a seizure, but it can happen. Grand mal seizure death is usually due to a condition called sudden unexpected death in epilepsy (SUDEP), according to the Centers for Disease Control and Prevention (CDC). It kills more than one out of a 1,000 people with epilepsy each year.

SUDEP is a bit of a medical mystery—some experts believe that the seizure causes breathing difficulties or an irregular heart rhythm, which results in death. People with severe epilepsy and/or those with poorly controlled seizures are considered to be at higher risk of SUDEP. 

That's why a treatment plan is so important for people who have seizures. "When patients are understandably reluctant to take more medicine, consider a surgery evaluation, etc., I fully understand," Dr. Rao says. "But one thing we do to impress on them the urgency of being aggressive with treatment is talk about SUDEP. We say, 'This is what we're trying to avoid. So maybe we should push on and not be satisfied until we have full control of the seizures.'"

How are grand mal seizures diagnosed and treated?

The specific characteristics of a tonic-clonic seizure make it relatively easy for doctors to diagnose—sometimes they can do so with access to a cell phone video or written account of the incident, the Epilepsy Foundation says. EEG or other tests may also help confirm a diagnosis or determine a cause.

Daily medications—anti-seizure medications (ASMs), anti-epileptic drugs (AEDs)—is one way to help people manage seizures, per the Epilepsy Foundation. But, like with many conditions, it may take some time for someone to find medication that works well for them.

There are also medications called "rescue medications" which are to be taken when someone has more seizures than usual, or to prevent further seizures (specifically tonic-clonic seizures) from happening. There are very specific instructions on how to take these medications, the Epilepsy Foundation says, so they should be used with caution and under a doctor's surveillance.

Dietary changes may also be used in conjunction with medications—the keto diet specifically was first meant to help manage epilepsy in children and adults. And certain surgeries or devices (vagus nerve stimulators or responsive neurostimulators) may be used if a person does not respond to medications.

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