Most people with epilepsy experience some kind of warning before a seizure, though the timing and type of warning vary widely. These pre-seizure changes fall into two distinct phases: a prodrome that can start hours or even days beforehand, and an aura that marks the very beginning of seizure activity in the brain. Nearly 65% of people with generalized epilepsy and about 68% of those with focal epilepsy report experiencing auras before tonic-clonic seizures when asked about specific symptoms.
The Prodrome: Hours to Days Before
The prodrome is the earliest warning phase, and it’s not technically part of the seizure itself. It’s a collection of subtle changes in mood, energy, and body sensations that can appear anywhere from 10 minutes to 3 days before a seizure, with most lasting between 30 minutes and 24 hours. These symptoms typically persist right up until the seizure begins.
Prodromal symptoms are often vague enough that they’re easy to dismiss. The most commonly reported ones include irritability, anxiety, confusion, headache, and mood swings. Some people feel unusually drowsy or develop a general sense of being unwell. Others notice more specific changes: difficulty finding words, arm or leg weakness, body soreness, nausea, unusual thirst, or sudden feelings of sadness or fear. Some patients also report autonomic shifts like palpitations, sweating, and increased urination in the hours leading up to a seizure.
Because these symptoms are so broad, many people only recognize them as a pattern in hindsight. Family members and caregivers sometimes pick up on prodromal changes before the person themselves does, noticing shifts in behavior or mood that reliably precede a seizure.
The Aura: The Seizure Has Already Started
An aura feels like a warning, but it’s actually the opening moments of the seizure. It represents electrical activity that has begun in one part of the brain but hasn’t yet spread. In medical terms, an aura is classified as a focal aware seizure, meaning you remain conscious and can often remember the experience afterward.
Auras typically last seconds to a couple of minutes, and what you feel depends on which part of the brain the seizure activity originates in. The experiences fall into several broad categories: sensory distortions, emotional shifts, cognitive disruptions, and physical sensations.
Sensory Distortions During an Aura
Some of the most distinctive pre-seizure experiences involve the senses. People commonly report a bitter or acidic taste in the mouth, strange offensive smells with no source, ringing or buzzing sounds, flickering or blurred vision, or visual hallucinations. These phantom sensations can be startlingly vivid.
Olfactory auras (phantom smells) are particularly notable because they’re rare enough that they often get misattributed to other conditions. In one documented case, a young child experienced recurrent episodes of perceiving unpleasant odors followed by nausea roughly five times per day, which turned out to be focal seizures caused by a brain tumor. Subtle sensory symptoms like these are sometimes the only sign of seizure activity, with no visible convulsions or loss of consciousness.
Déjà Vu, Fear, and Other Cognitive Shifts
A sudden, overwhelming sense of déjà vu is one of the hallmark aura experiences, and it’s been linked to seizure activity for over a century. When déjà vu occurs as part of a seizure, it originates in the medial temporal lobe, a brain region involved in memory formation. People describe it as an intense, unmistakable feeling of having lived through the current moment before.
The opposite experience, called jamais vu, also occurs. This is when something deeply familiar, like your own home or a close friend’s face, suddenly feels completely foreign. Both experiences are qualitatively different from their everyday counterparts. Research suggests that seizure-related déjà vu is subjectively distinguishable from the ordinary kind because additional brain regions get activated during the seizure, creating a more complex and often more unsettling sensation.
Strong emotional surges are also common during auras. Some people feel a sudden wave of intense fear or dread with no obvious cause. Others experience unexplained joy, sadness, or anger. These emotions can arrive fully formed and overwhelming, then vanish just as abruptly.
Physical Sensations in the Body
Many people feel a “rising” sensation in the stomach, often described as the feeling you get on a roller coaster or in a fast elevator. This epigastric aura is one of the most frequently reported physical warnings. Tingling, numbness, dizziness, and an out-of-body sensation are also common. Some people notice subtle twitching in an arm or leg, or localized pain in the head or limbs.
Heart rate changes are among the earliest measurable shifts before a seizure. Even in people who don’t consciously feel their heart racing, monitoring equipment can detect increases in heart rate and other autonomic nervous system changes in the minutes before seizure onset. These changes reflect the brain’s influence over the body’s automatic functions as electrical activity begins to ramp up.
Why Some People Get Warnings and Others Don’t
Whether you experience a warning depends largely on where in the brain the seizure starts and how quickly it spreads. Focal seizures, which begin in one specific area, are more likely to produce a distinct aura because the activity stays localized long enough for you to consciously perceive it. The specific symptoms map to the brain region involved: temporal lobe seizures tend to produce déjà vu, emotional changes, and stomach sensations, while occipital lobe seizures are more likely to cause visual disturbances.
Generalized seizures, which involve both sides of the brain from the start, were long thought to strike without warning. But structured interviews have challenged that assumption. When people with generalized epilepsy are asked open-ended questions, about 21% report auras. When asked about specific symptoms using a checklist, that number jumps to nearly 65%. This suggests many people do experience subtle warnings but don’t recognize them as seizure-related or don’t think to mention them.
Absence seizures, a type of generalized seizure that causes brief lapses in awareness, are an exception. These typically last only a few seconds and often go unnoticed even by the person having them, with little to no perceptible warning.
What’s Happening in the Brain
In the minutes before a seizure becomes visible, the brain is already changing. Recordings of electrical activity show that the area where the seizure will start begins producing unusually strong slow-wave signals, similar to the patterns seen during deep sleep. This reflects neurons beginning to fire in abnormal synchrony.
As the seizure approaches, faster brain wave activity also increases at the seizure’s point of origin, then gradually spreads to surrounding regions. This spreading pattern of abnormal connectivity mirrors the progression many people feel during an aura: a sensation that starts small and specific, then builds and broadens. The shift from localized abnormality to widespread disruption is what eventually tips the brain into a full seizure.
Using Pre-Seizure Warnings Practically
If you experience consistent pre-seizure symptoms, tracking them can be genuinely useful. Keeping a seizure diary that includes prodromal mood changes, sleep quality, and any aura symptoms helps identify your personal pattern. Some people learn to recognize their prodrome reliably enough to take precautions: moving to a safe location, lying down, alerting someone nearby, or in some cases using prescribed rescue medication.
Not every aura leads to a larger seizure. Some people experience isolated auras that resolve on their own, which are technically focal aware seizures that simply don’t spread. But a change in aura frequency or character, or the appearance of auras in someone who previously had none, is worth reporting to your neurologist because it can signal a shift in seizure activity.