A grand mal seizure causes a loss of consciousness and violent muscle contractions. It's the type of seizure most people picture when they think about seizures.
A grand mal seizure — also known as a generalized tonic-clonic seizure — is caused by abnormal electrical activity throughout the brain. Usually, a grand mal seizure is caused by epilepsy. But sometimes, this type of seizure can be triggered by other health problems, such as extremely low blood sugar, a high fever or a stroke.
Many people who have a grand mal seizure never have another one and don't need treatment. But someone who has recurrent seizures may need treatment with daily anti-seizure medications to control and prevent future grand mal seizures.
Products & Services
Grand mal seizures have two stages:
- Tonic phase. Loss of consciousness occurs, and the muscles suddenly contract and cause the person to fall down. This phase tends to last about 10 to 20 seconds.
- Clonic phase. The muscles go into rhythmic contractions, alternately flexing and relaxing. Convulsions usually last one to two minutes or less.
The following signs and symptoms occur in some but not all people with grand mal seizures:
- A scream. Some people may cry out at the beginning of a seizure.
- Loss of bowel and bladder control. This may happen during or following a seizure.
- Unresponsiveness after convulsions. Unconsciousness may persist for several minutes after the convulsion has ended.
- Confusion. A period of disorientation often follows a grand mal seizure. This is referred to as postictal confusion.
- Fatigue. Sleepiness is common after a grand mal seizure.
- Severe headache. Headaches may occur after a grand mal seizure.
When to see a doctor
Seek immediate medical help if any of the following occurs:
- The seizure lasts more than five minutes
- Breathing or consciousness doesn't return after the seizure stops
- A second seizure follows immediately
- You have a high fever
- You're experiencing heat exhaustion.
- You're pregnant.
- You have diabetes.
- You've injured yourself during the seizure.
If you experience a seizure for the first time, seek medical advice.
Additionally, seek medical advice for yourself or your child:
- If the number of seizures experienced increases significantly without explanation
- If new seizure signs or symptoms appear
Get the latest epilepsy information from Mayo Clinic delivered to your inbox.
Subscribe for free and receive the latest on epilepsy treatment, care and management.
ErrorEmail field is required
ErrorInclude a valid email address
To provide you with the most relevant and helpful information, and understand which information is beneficial, we may combine your email and website usage information with other information we have about you. If you are a Mayo Clinic patient, this could include protected health information. If we combine this information with your protected health information, we will treat all of that information as protected health information, and will only use or disclose that information as set forth in our notice of privacy practices. You may opt-out of email communications at any time by clicking on the unsubscribe link in the e-mail.
Thanks for Subscribing
You will receive the first epilepsy email message in your inbox shortly. This message will include the latest treatment options, innovations and other information from our epilepsy experts.
You may opt out of these emails any time by clicking the unsubscribe link in the email.
Sorry something went wrong with your subscription
Please, try again in a couple of minutes
Grand mal seizures occur when the electrical activity over the whole surface of the brain becomes abnormally synchronized. The brain's nerve cells normally communicate with each other by sending electrical and chemical signals across the synapses that connect the cells.
In people who have seizures, the brain's usual electrical activity is altered and many nerve cells fire at the same time. Exactly what causes the changes to occur often remains unknown.
However, grand mal seizures are sometimes caused by underlying health problems, such as:
Injury or infection
- Traumatic head injuries
- Infections, such as encephalitis or meningitis, or a history of such infections
- Injury due to a previous lack of oxygen
Congenital or developmental abnormalities
- Blood vessel malformations in the brain
- Genetic syndromes
- Brain tumors
- Very low blood levels of glucose, sodium, calcium or magnesium
- Using or withdrawing from drugs, including alcohol
Risk factors for grand mal seizures include:
- A family history of seizure disorders
- Any injury to the brain from trauma, a stroke, previous infection and other causes
- Sleep deprivation
- Medical problems that affect electrolyte balance
- Illicit drug use
- Heavy alcohol use
Having a seizure at certain times can lead to circumstances that are dangerous for you or others. You might be at risk of:
- Falling. If you fall during a seizure, you can injure your head or break a bone.
- Drowning. If you have a seizure while swimming or bathing, you're at risk of accidental drowning.
- Car accidents. A seizure that causes either loss of awareness or control can be dangerous if you're driving a car or operating other equipment.
- Pregnancy complications. Seizures during pregnancy pose dangers to both mother and baby, and certain anti-epileptic medications increase the risk of birth defects. If you have epilepsy and plan to become pregnant, work with your doctor so that he or she can adjust your medications and monitor your pregnancy, as needed.
- Emotional health issues. People with seizures are more likely to have psychological problems, such as depression and anxiety. Problems may be a result of difficulties dealing with the condition itself as well as medication side effects.
Feb. 24, 2021