What Causes Seizures?

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Key Takeaways:

  • Seizures happen when there is a burst of electrical activity in the brain.
  • Epilepsy is the most common cause of seizures.
  • Infections, injuries, tumors, and other problems can also cause seizures.
  • Some common seizure triggers are drugs, alcohol, lack of sleep, stress, and fever.
  • For some seizures, no cause can be found.


Have you ever seen someone suddenly shake or jerk uncontrollably? They may have temporarily lost awareness or control of their body. If so, that person was likely having a seizure. Seizures happen when there is a disruption in the brain’s electrical activity. Understanding what causes seizures can help people identify warning signs and get proper treatment. This article will explore the most common causes and triggers for seizures. Read on to learn what leads to these sudden electrical bursts in the brain.

Seizures can be alarming to witness and experience. However, knowing what triggers them can help avoid recurrences or prepare for future events. This comprehensive guide covers the key factors that provoke seizure activity. Discover the genetic, environmental, and lifestyle factors that contribute to seizures.

Learning about seizure causes empowers individuals to take preventative measures. It also allows people to recognize early symptoms and seek medical care promptly. With this crucial information, readers can better manage seizure conditions in themselves or loved ones. Continue reading to uncover the origins of seizure activity in the brain.

What Is a Seizure?

Before diving into causes, let’s review what exactly a seizure is. A seizure happens when there is a sudden burst of abnormal electrical activity in the brain. This disrupts the normal communication between brain cells.

What Causes Seizures?

During a seizure, a person may experience sudden changes in behavior, movements, sensations, or levels of awareness. For example, they may stare blankly, jerk or twitch uncontrollably, fall down, or lose consciousness. Seizures typically last from a few seconds to a few minutes.

When seizures keep happening over time, this is known as epilepsy or a seizure disorder. Epilepsy is a chronic condition that causes recurrent, unprovoked seizures. An estimated 3 million adults and 500,000 children have epilepsy in the U.S.

What Is the Most Common Cause of Seizures?


By far, the most common cause of seizures is epilepsy. Epilepsy is a brain disorder characterized by repeated seizures over time. It results from temporary changes in brain electrical activity.

Doctors aren’t always sure what brings on epilepsy. However, research shows genetics play a major role. Epilepsy often runs in families. Scientists have identified many genes associated with epilepsy.

Other factors like head trauma, lack of oxygen at birth, and brain infections may also contribute to developing epilepsy later in life. Overall, the cause of epilepsy remains unknown in about 50% of cases.

What Other Medical Conditions Can Cause Seizures?

While epilepsy is the primary cause, seizures can also result from:


  • Meningitis – infection and swelling of membranes surrounding the brain
  • Encephalitis – infection and inflammation of the brain itself
  • Brain abscess – confined collection of pus and infected material

Brain Injury

  • Trauma – car accident, violent blow to the head, sports injury
  • Stroke – disruption of blood and oxygen flow to the brain

Brain Tumors

  • Cancerous – abnormal growth like glioblastoma
  • Noncancerous – benign masses or lesions

Metabolic Problems

  • Low blood sugar – hypoglycemia
  • Low sodium – hyponatremia
  • Kidney failure
  • Liver failure

In these cases, seizures are symptoms of an underlying problem. Treating the root cause, whether an infection, tumor, or metabolic disorder, is key to managing seizures.

Anti-seizure medications may provide temporary relief in the short term. But addressing the primary medical issue is essential to preventing recurrent seizures.

What Can Trigger a Seizure?

For people prone to seizures, certain factors can suddenly provoke seizure activity. These are known as triggers or precipitants. Some common seizure triggers include:

Illicit Drugs

Illegal drug use is a preventable cause of seizures. Drugs that lower seizure threshold and provoke seizures include:

  • Cocaine
  • Heroin
  • LSD
  • Ecstasy
  • Methamphetamines

Alcohol Use

Drinking excess alcohol or acute alcohol withdrawal after heavy drinking can trigger seizures. This is a serious condition called alcohol withdrawal seizures.


Extremely low blood sugar levels, called hypoglycemia, can cause seizures in diabetics using insulin. Eating regular healthy meals is key for prevention.

Flashing Lights

Flickering or flashing lights and patterns can trigger seizures in people with photosensitive epilepsy. This includes strobe lights, video games, screensavers, sun flickering through trees, and more.

Lack of Sleep

Not getting enough sleep lowers seizure threshold. Adults should aim for 7-9 hours of sleep per night.

High Stress

Extreme emotional distress or anxiety can provoke seizures in some cases. Stress management skills are helpful.

High Fever

Fevers above 101°F (38°C) may trigger fever-related seizures, especially in young children. These are called febrile seizures.

Other Triggers

  • Forgetting to take prescribed seizure medications
  • Missing meals/fluctuating blood sugar
  • Certain medications like antibiotics
  • Menstrual cycle hormonal changes
  • Bright, flashing, or high contrast patterns

Learning individual seizure triggers enables a person to avoid or minimize exposure when possible. Tracking potential triggers in a seizure diary can also uncover patterns for better management.

Are Seizures Ever Idopathic (Cause Unknown)?

For some people who experience seizures, no underlying cause can be found. These are termed idiopathic seizures. Idiopathic means arising spontaneously or from an unknown cause.

Up to 60-70% of all seizures have no identifiable cause. In many cases, a person experiences seizures, but medical testing reveals no structural issues or abnormalities in the brain. These unexplained, spontaneous seizures are challenging to treat or prevent since the origin is unknown.


In summary, seizures stem from disruptions in normal electrical brain activity. Epilepsy is the most prevalent disorder causing recurrent, unprovoked seizures over time. Genetics play a key role in many forms of epilepsy.

Secondary causes like infections, head injuries, brain tumors, and metabolic problems may also lead to seizures. And for those prone to seizures, triggers like drug use, alcohol, sleep deprivation, flashing lights, and stress can provoke seizure events. In some cases, no cause can be identified at all.

Learning about the diverse causes and triggers for seizures is empowering. This enables individuals to take preventative measures, recognize warning signs early, and seek prompt treatment. While seizures can be unpredictable, identifying potential risk factors and being prepared with proper medication and first aid makes all the difference.

Frequently Asked Questions

What percentage of seizures are caused by epilepsy?

Epilepsy is responsible for around 60-70% of all seizures, making it by far the most common cause. The underlying mechanism of epilepsy is not always fully understood, but genetics appear to play a major role.

Can a head injury cause seizures?

Yes, head trauma from an accident, violent blow, or sports injury can absolutely cause seizures. Any type of injury that impacts the brain can potentially disrupt normal electrical activity and provoke seizures temporarily or long-term.

If a child has a seizure with high fever, does it mean they have epilepsy?

Not necessarily. Many children, especially under age 5, experience febrile seizures brought on by high fevers above 101°F (38°C). Febrile seizures do not necessarily indicate epilepsy. Only if seizures continue to occur after the fever subsides would epilepsy be suspected.

Are seizures caused by mental illness?

No, seizures are not caused by mental illnesses like depression, anxiety, bipolar disorder, or schizophrenia. However, the stress of dealing with mental health issues could potentially trigger seizures in someone already susceptible.

Can dehydration and electrolyte imbalances cause seizures?

Yes. Severe dehydration, causing low sodium levels (hyponatremia) and imbalanced electrolytes can lower seizure threshold. That’s why it’s important to stay well hydrated, especially in hot environments or when ill.

If all medical tests are normal, does that mean the seizures are not serious?

Not necessarily. Many times, all diagnostic testing including CT scans, MRIs, and EEGs come back normal. However, this does not mean the seizures are not serious or life-impacting. Appropriate medication and lifestyle adjustments are still needed to control symptoms.

What should you do if you think you missed a dose of seizure medication?

Missing doses of anti-seizure medication can trigger breakthrough seizures. If you think a dose was missed, take the medication as soon as you remember if it’s still within 4 hours of the scheduled time. Otherwise, skip the missed dose and take the next one on schedule. Never double up doses.

Can anxiety cause seizures even if I don’t have epilepsy?

It’s rare, but in some cases extreme anxiety can provoke seizures even without an epilepsy diagnosis. This is more likely if you have a family history or genetic predisposition. Relaxation techniques, therapy, and anti-anxiety strategies may help lower seizure risk.

Are there any warning signs before a seizure?

Some patients experience warning signs called auras before seizures occur. These may include a strange sensation, smell, visual change, racing thoughts, or premonition. Realizing individual auras can allow a person to get to a safe place before losing consciousness.

If my MRI and EEG are normal, does it rule out epilepsy?

Not necessarily. Many patients with epilepsy have normal MRI and EEG results. A normal EEG does not definitively rule out seizure disorders. Likewise, an abnormal EEG does not definitively diagnose epilepsy. The EEG results must be correlated with the person’s clinical history

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