How likely am I to have another seizure? 

The question of whether a seizure will happen again is one of the most significant concerns for anyone who has experienced a first event. Clinically the likelihood of recurrence is not the same for everyone: it is determined by a complex interplay of neurological factors, the results of diagnostic tests, and the underlying cause of the initial event. While experiencing a single seizure does not automatically mean a person has epilepsy, it does indicate that the brain has reached its seizure threshold once, and the goal of medical investigation is to determine how likely it is to happen again. 

In a medical context, specialists use a risk stratification approach to estimate the probability of a second seizure. This assessment is vital because it informs the decision of whether to start long term anti seizure medication. For some, the risk is low enough that a wait and see approach is appropriate, while for others, the clinical evidence suggests a high probability of recurrence, making proactive treatment the safest pathway. This guide explores the statistics and factors that influence the likelihood of future seizures. 

What we will discuss in this article 

• Statistical recurrence risk after a single unprovoked seizure 

• How abnormal EEG patterns influence the probability of a second event 

• The role of brain imaging in identifying structural risks for recurrence 

• The impact of the underlying cause on long term seizure stability 

• How starting treatment reduces the likelihood of further seizures 

• Lifestyle factors and triggers that can affect your seizure threshold 

• Emergency guidance for identifying signs of health deterioration 

Recurrence risk after a first seizure 

Statistically, the highest risk for a second seizure occurs within the first six to twelve months following the initial event. 

General statistics 

For individuals who experience a single, unprovoked seizure and have normal clinical tests, the risk of having a second seizure is approximately 30 to 40 percent. However, if there is an identifiable clinical factor such as an abnormal EEG or an old brain injury seen on an MRI: that risk can rise to over 60 or 90 percent. When the risk of a second seizure within the next ten years is estimated to be 60 percent or higher, a clinical diagnosis of epilepsy is typically made, even after only one event. 

The role of diagnostic evidence 

Clinical investigations are the most important tools for predicting your individual risk level. 

EEG and MRI findings 

An Electroencephalogram, or EEG, that shows epileptiform activity such as spikes or sharp waves: is one of the strongest predictors of recurrence. It indicates that the brain remains in a state where an electrical surge is likely to happen again. 

Similarly, a Magnetic Resonance Imaging, or MRI, scan that reveals a structural abnormality, such as scar tissue from a previous injury or a malformed blood vessel, suggests a permanent focal point for future seizure activity. If both tests are normal, the statistical likelihood of another seizure remains on the lower end of the spectrum. 

Comparison of recurrence risk factors 

Clinical Factor	Lower Recurrence Risk	Higher Recurrence Risk
EEG Result	Normal activity	Epileptiform discharges or spikes
Brain Imaging	Normal MRI	Structural lesion or scar tissue
Seizure Type	Occurred during sleep only	Occurred while awake or both
Underlying Cause	Unknown or Idiopathic	Known brain injury or stroke
Neurological Exam	Normal	Presence of neurological deficits
Timing	First seizure in childhood	First seizure in adulthood

Impact of treatment on future risk 

Starting anti seizure medication is the primary clinical method for lowering the probability of another event. Effective medication works by stabilizing the electrical environment of the brain and raising the seizure threshold. For many people, the first medication they try is successful in preventing further seizures. 

If treatment is started after a first seizure, the risk of a second event is reduced significantly. However, clinicians often weigh this reduction in risk against the potential side effects of the medication. The decision to treat is a collaborative one based on the statistical risk of recurrence and the impact a second seizure would have on your safety and lifestyle, such as your ability to drive. 

Lifestyle and the seizure threshold 

Beyond medical treatment, your daily habits can influence how likely you are to have another seizure by affecting your brain’s baseline stability. 

Certain factors are known to temporarily lower the seizure threshold, making a recurrence more likely even if your underlying risk is moderate. These include significant sleep deprivation, high levels of psychological stress, and the use of certain substances or heavy alcohol consumption. By maintaining a regular sleep schedule and managing stress, you can help keep your brain within a safe electrical range and minimize the chance of a breakthrough event. 

To summarise 

The likelihood of having another seizure depends heavily on the results of your clinical tests and the underlying cause of the first event. While a single seizure leads to a second event in about 40 percent of people with normal tests, this risk increases significantly if an EEG or MRI reveals abnormal activity or structural changes. By working with your specialist to interpret these results, you can determine your individual risk profile and decide whether starting medication is the best step for your safety. Proactive management and lifestyle stability remain the most effective ways to lower the probability of future seizures. 

Emergency guidance 

If you have already had one seizure, it is vital to have a safety plan in place. Call 999 immediately if a subsequent seizure lasts more than five minutes, if a person has multiple seizures without regaining consciousness, or if they are injured during an event. If you experience a second seizure, you must seek an urgent clinical review with a neurologist. A second unprovoked seizure usually confirms a diagnosis of epilepsy and indicates that the brain seizure threshold is consistently low, requiring a formal assessment of your treatment plan to ensure long term safety. 

Authority Snapshot 

Dr. Rebecca Fernandez is a UK trained physician with an MBBS and experience in general surgery, cardiology, internal medicine, gynecology, intensive care, and emergency medicine. She has managed critically ill patients, stabilised acute trauma cases, and provided comprehensive inpatient and outpatient care. In psychiatry, Dr. Fernandez has worked with psychotic, mood, anxiety, and substance use disorders, applying evidence based approaches such as CBT, ACT, and mindfulness based therapies. Her skills span patient assessment, treatment planning, and the integration of digital health solutions to support mental well being in 2026.