How to Tell If a Seizure Is Coming: Warning Signs

Roughly half of people with epilepsy experience some kind of warning before at least some of their seizures, and those warnings tend to be consistent from one episode to the next. The specific form a warning takes depends on the type of epilepsy and which brain region is involved, but the most common experiences include headaches, a rising feeling in the stomach, mood shifts, unusual smells or tastes, visual disturbances, and an overwhelming sense of déjà vu. Not every seizure announces itself, and some types almost never do, but learning to recognize the signs your body does give you can mean the difference between being caught off guard and having time to sit down, call for help, or take medication.

Prodromes and Auras Are Two Different Warnings

People often lump all pre-seizure experiences together, but there are actually two distinct phases that can precede a seizure, and they operate on very different timescales. A prodrome is a set of vague, general symptoms that can appear hours or even a full day before a seizure. Common prodromal symptoms include irritability, headache, difficulty concentrating, mood changes, and fatigue. These are not part of the seizure itself; they reflect broader shifts in brain activity that precede the electrical storm. A large multicentre study found that the main prodromal symptoms were headache, epigastric sensation, and dysphoria, and that the interval between these warnings and the seizure was usually long enough for the person to remain able to act.¹

An aura, by contrast, is a brief sensory or psychological experience that happens seconds to minutes before a seizure. Neurologically, an aura is not a warning before the seizure so much as the opening act of the seizure itself: it is caused by abnormal electrical activity that has started in one part of the brain but has not yet spread. Because the activity is still localized, you remain conscious during an aura, which is why you can perceive and later describe the experience. The nature of the aura points directly to where the seizure begins in your brain, which is one reason neurologists ask about aura details so carefully.

Sensory Warnings You Can See, Hear, Smell, or Taste

When the electrical discharge starts in a brain region tied to one of your senses, the aura takes the form of a sensory hallucination. Visual auras can range from simple flashing lights or colored spots to complex scenes. Auditory auras might be a buzzing sound, a ringing, or in rarer cases, fragments of music or voices. Gustatory auras produce a sudden metallic or bitter taste in the mouth. Cutaneous sensations, like tingling or numbness in a hand or face, are also common. When brain regions related to sensory integration are involved, even complex hallucinations can arise, such as perceiving full visual scenes or hearing music.²

Olfactory auras deserve special mention because they are one of the more dramatic and often discussed warning signs. The stereotype is a foul, burning rubber smell, but olfactory auras are more variable than most people realize. In a study of patients with olfactory epileptic auras, the sensations were unpleasant in only a minority of cases; some patients described neutral or even indistinguishable odors. These olfactory auras frequently evolved into larger seizures involving loss of awareness.³ If you suddenly smell something nobody around you can identify, and this has happened before with the same smell, pay attention. The consistency of the experience is what separates a seizure aura from a random weird smell.

The Rising Feeling in Your Stomach

One of the most frequently reported seizure warnings is an abdominal aura, often described as a rising sensation that starts somewhere in the stomach and moves upward toward the chest or throat. People liken it to the dropping feeling on a roller coaster, or to a bubble of air traveling up through the torso. This sensation is strongly associated with temporal lobe epilepsy. In a study of patients with mesial temporal sclerosis, about two-thirds experienced abdominal auras, with the rising sensation typically starting in the area around the navel or just below the ribs and climbing to the chest.⁴

This symptom gets overlooked partly because it sounds like garden-variety nausea or anxiety. The key difference is that a seizure-related abdominal aura has a characteristic direction, rising upward, and it happens repeatedly in the same pattern before seizures. Regular stomach upset does not behave that way. If you or someone you care for describes a rising feeling that reliably precedes episodes of confusion or loss of awareness, that is worth mentioning to a neurologist even if no one has used the word “seizure” yet.

Déjà Vu and Sudden Emotional Shifts

Nearly everyone has experienced déjà vu, but in epilepsy, it takes on a distinct character. Seizure-related déjà vu tends to be more intense, longer-lasting, and more disturbing than the fleeting everyday version. It has been linked to focal seizures for over a century, particularly those originating in the medial temporal lobe, the brain region involved in forming and retrieving memories.⁵ The temporal lobe is where memory circuitry lives, so abnormal electrical activity there can produce illusions of familiarity with the current experience or hallucinatory recall of memories that feel vivid and real.⁶

A related phenomenon is the “dreamy state,” where people feel disconnected from their surroundings or as though reality has become slightly unreal. Sudden fear, panic, or a sense of impending doom can also serve as aura symptoms, especially in temporal lobe epilepsy. These emotional experiences are not reactions to realizing a seizure is coming; they are direct products of the electrical activity itself. Some people report feelings of intense joy or calm instead, though fear is more common.

One important clinical point: déjà vu is not exclusive to focal epilepsy. A systematic review found that people with idiopathic generalized epilepsy can also experience déjà vu and other auras, which can lead to misdiagnosis if a clinician automatically assumes an aura means focal onset.⁷ This matters because the treatment strategies for focal and generalized epilepsy can differ.

Not Every Seizure Gives a Warning

It is worth being honest about the limits here. Warning symptoms appear primarily in focal epilepsies, where the electrical discharge starts in a defined area and may or may not spread. In generalized epilepsies, where the abnormal activity fires across both hemispheres simultaneously, there is often no conscious warning at all. The seizure simply happens. The same multicentre study that found roughly half of patients experienced warnings also noted that warnings mainly preceded generalized tonic-clonic seizures that evolved from a focal onset, and complex partial seizures, rather than seizures that begin as generalized from the start.¹

Even among people who do get warnings, the warning does not accompany every seizure. Some people report auras before most of their seizures, while others notice them only occasionally. And a meaningful number of people with epilepsy never experience any warning at all. So while learning your personal pattern is genuinely useful, it is not a substitute for other safety strategies. You cannot rely on always getting advance notice.

When the Warning Looks Like a Migraine

Visual auras create a particular source of confusion because they occur in both epilepsy and migraine, two conditions that can coexist in the same person. Telling them apart matters because the treatment implications are completely different. The most reliable distinguishing feature is duration. In a study comparing visual auras across the two conditions, epileptic visual auras lasted a median of about one minute, while migraine visual auras lasted a median of twenty minutes. A cutoff of five minutes or longer identified migraine patients with high accuracy.⁸

Beyond timing, the two conditions produce qualitatively different visual experiences. Epileptic visual auras tend to affect one side of the visual field consistently, the same side every time. Migraine auras are more likely to spread across the visual field in a centrifugal or centripetal pattern, expanding outward or contracting inward. And accompanying symptoms like nausea, vomiting, or sensitivity to light and sound were strong indicators of migraine rather than epilepsy; in the same study, none of the epilepsy patients reported those accompaniments alongside their visual auras.⁸ If you experience visual disturbances and are unsure whether they are migraine-related or seizure-related, tracking the duration and pattern gives your doctor the most useful information.

Warning Signs in Young Children

Identifying pre-seizure warnings in babies and toddlers presents a unique challenge, because auras are subjective experiences that require the ability to describe what you are feeling. A study of seizure symptomatology in children under three found that auras were not observed in that age group.⁹ That does not necessarily mean the youngest children do not have internal warning experiences; it means they cannot communicate them.

Caregivers of children with epilepsy often become skilled at noticing behavioral changes that precede seizures even without verbal reports. A child might become unusually clingy, stop what they are doing and stare, or display a sudden mood change. Some children will instinctively reach for a parent or move toward a familiar space. These behavioral cues are not the same as an aura, and they are harder to study systematically, but they can be genuinely useful in a practical sense. If you care for a young child with epilepsy, keeping a log of what you notice before seizures can help both you and the treatment team identify patterns.

What Caregivers Notice

The perspective of someone living with a person who has epilepsy is a valuable and underappreciated source of data. In one study, about three-quarters of caregivers reported that their patient experienced at least one recognizable symptom before a seizure. The same study found that the vast majority of caregivers could identify specific events or triggers that seemed to precipitate seizures. More than half reported that their patient had tried at least one technique to stop or shorten a seizure once they recognized it starting.¹⁰

This matters because people with epilepsy sometimes cannot recall or report their own pre-seizure experiences, especially if the seizure impairs awareness early. A caregiver who notices that a person always gets pale, or goes quiet, or rubs their hands in a particular way before a seizure provides clinically useful observations. If you are a caregiver, your pattern recognition is not imaginary. Share it with the neurologist.

What to Do When You Recognize a Warning

If you have learned your personal aura pattern, that brief window of awareness before a seizure can be used practically. The most immediate priorities are safety-related: stop driving, move away from stairs or sharp objects, sit or lie down on a soft surface, and let someone nearby know what is about to happen. Some people carry a card or wear a medical alert bracelet so that bystanders know what is happening if they lose consciousness before they can explain.

There is also growing interest in whether medication administered during the aura window can prevent a seizure from progressing. A phase 2b clinical trial tested an inhaled form of alprazolam (delivered through a device called Staccato) for rapid seizure termination when patients recognized the onset of a predictable seizure pattern. About two-thirds of patients who used either the 1.0 mg or 2.0 mg dose were classified as responders, compared to about 43% of those on placebo. The most common side effects were cough and drowsiness.¹¹ This approach is still relatively new, but it underscores why recognizing your warning signs is clinically valuable: the earlier you act, the more options may be available.

Your Brain Changes Before You Feel Anything

The subjective experience of a warning is only part of what happens before a seizure. Research using brain recordings has found measurable changes in electrical activity well before the seizure becomes clinically apparent. One early study found that shifts toward more synchronized brain states could be detected up to 25 minutes before a seizure occurred.¹² More recent work has confirmed and refined that picture: in the minutes before a seizure, the balance between excitation and inhibition in the brain shifts in detectable ways, with slower brain rhythms gaining power across both the seizure focus and the rest of the cortex.¹³

These findings are why the idea of seizure forecasting, predicting a seizure before the person is even aware of it, is not science fiction. The brain does not flip a switch. It undergoes a gradual transition that is, at least in principle, detectable with the right tools.

Wearable Devices and Seizure Forecasting

The most exciting frontier in seizure warning is technology that detects physiological changes you cannot feel yourself. Wearable sensors that track heart rate, skin conductance, and movement patterns are being studied for their ability to forecast seizures before they happen. In one study of patients wearing smartwatch-type devices, seizures were predicted above chance in all eleven participants when using an hourly forecast. The average time spent in a high-risk state before a seizure was about 37 minutes. The most predictive signals came from cyclic patterns in heart rate, including circadian rhythms and longer multi-day cycles unique to each individual.¹⁴

A larger study using wristband sensor data and machine-learning algorithms found that better-than-chance seizure prediction was achievable in about 43% of patients, with performance improving as the system gathered more data over time. Prediction accuracy did not differ between generalized and focal seizure types, which is encouraging given that generalized seizures are the ones least likely to produce a subjective warning.¹⁵ These systems are still being developed and are not yet reliable enough for clinical use in most settings, but the trajectory is promising.

Dogs That Detect Seizures by Smell

One of the more surprising areas of research involves trained and even untrained dogs detecting seizures through scent. The basic premise is that the physiological changes preceding a seizure produce volatile organic compounds, chemicals released through the skin or breath, that dogs can smell even when humans cannot. In a study where trained dogs were presented with body-odor samples from people with epilepsy, three out of five dogs achieved 100% sensitivity and specificity in identifying the seizure-associated scent, and the other two dogs still performed well above chance. The dogs identified the correct sample in an average of about nine seconds.¹⁶

When tested in a more real-world scenario, with samples collected hourly from people being monitored, dogs identified the seizure scent before about 79% of seizures, with an average warning time of roughly 68 minutes.¹⁶ Even untrained pet dogs appear to react differently to seizure-related odors. A study exposing pet dogs to body-odor samples found that the dogs made significantly more eye contact with their owners when presented with pre-seizure, seizure, and post-seizure odors compared to control odors, suggesting the dogs registered something unusual about the scent even without specific training.¹⁷

Seizure-alert dogs are already used by some people with epilepsy, though access is limited by cost and availability. The research lends credibility to anecdotal reports from dog owners who insist their pet acts strangely before a seizure. It also raises the possibility that whatever chemical signature dogs are detecting could eventually be identified and measured with an electronic sensor, potentially creating a biological early-warning system that does not require a dog.