A seizure is often the first sign that something is wrong inside the brain - and for many families, it is the event that leads to a glioblastoma diagnosis. Even when the initial scan happens before any seizure occurs, the question of whether to start antiseizure medication just in case reaches most care teams within the first week. The answer is not straightforward. The wrong decision in either direction carries real costs for a patient who may already be managing surgery, radiation, and chemotherapy at the same time.
Do all glioblastoma patients need antiseizure medication?
No. Current guidelines from the Society for Neuro-Oncology and the European Association for Neuro-Oncology show insufficient evidence to support routine preventive antiseizure medication in glioblastoma patients who have never had a seizure. If a seizure has already occurred, treatment is clearly appropriate. If not, the decision depends on individual risk factors and requires a careful discussion with the care team.
Why glioblastoma causes seizures
Glioblastoma grows inside brain tissue rather than pressing on it from outside. The tumor disrupts the normal electrical activity between neurons - the cells that carry signals through the brain. It also releases glutamate, an excitatory neurotransmitter that makes nearby neurons fire too easily. Research shows that neuroinflammation and changes in the tumor microenvironment further increase electrical instability in tissue adjacent to the tumor, which is why seizures can begin in areas near the tumor, not just inside it.
Seizures in glioblastoma patients can look very different from the convulsions most people picture. Some patients lose awareness for a few seconds. Others feel tingling or weakness in one limb, notice a brief unusual smell, or have a visual disturbance lasting under a minute. These focal seizures - arising from one region of the brain rather than the whole brain at once - often go unrecognized because they do not match the expected picture. Knowing what to watch for matters: unrecognized seizures typically go untreated longer than they should.
Who is at highest risk for a first seizure?
Seizure risk is not the same for every glioblastoma patient. Several factors raise the probability significantly:
- Tumor location: Tumors in the temporal, frontal, and parietal lobes carry higher seizure risk than those in deeper structures or the brainstem.
- Cortical involvement: Tumors that extend into or near the cortex - the brain's outer layer - are more likely to trigger seizures than those confined to the white matter deeper inside.
- A seizure at presentation: If a seizure occurred before or at the time of diagnosis, the likelihood of further seizures without ongoing treatment is high.
- Younger age: Younger patients with brain tumors tend to have higher seizure rates, possibly because younger brain tissue is more electrically active overall.
- Molecular markers: IDH mutations are more common in lower-grade gliomas, which have higher seizure rates than GBM. Most glioblastoma is IDH-wildtype. Understanding your molecular profile is one part of a complete seizure risk picture your neuro-oncologist can walk you through.
The prophylaxis debate: why seizure-naive patients are not routinely treated
For decades, it was standard practice to start all brain tumor patients on antiseizure medication at diagnosis. That practice has changed. The Society for Neuro-Oncology reviewed this question and found that long-term preventive medication in patients without prior seizures showed no consistent benefit, while adding medication burden, drug interactions, and potential side effects to an already demanding treatment plan. The current consensus is to treat seizures when they occur, not to prevent them speculatively in patients who have never had one.
The perioperative period - the days immediately before and after brain surgery - is a partial exception. Many centers give a short course of antiseizure medication around the time of craniotomy, typically for up to one week, then reassess. If no seizures occur in that window, the medication is often tapered and stopped. This balances the real risk of a post-surgical seizure against the costs of indefinite treatment.
If your care team has recommended ongoing preventive medication for a seizure-naive patient, asking what specific risk factors they are responding to is a reasonable and appropriate question. Centers differ in institutional protocols, and understanding the reasoning helps you participate meaningfully in the decision. A neuro-oncology second opinion can also clarify whether the recommendation reflects your patient's specific situation or a more general institutional policy.
Medication options when treatment is needed
When antiseizure medication is clearly indicated - because a seizure has already occurred, or because specific risk factors make prevention appropriate - the choice of agent matters. Not all antiseizure drugs behave the same way in a glioblastoma context, particularly when chemotherapy is running alongside.
Levetiracetam
Levetiracetam is now the most widely used antiseizure medication in brain tumor patients. Its central advantage is that it does not activate the liver's enzyme system. Many older drugs - particularly phenytoin and carbamazepine - speed up the liver's breakdown of other medications, which can reduce the effectiveness of chemotherapy agents and steroids like dexamethasone. Levetiracetam avoids this interaction. Research has investigated whether levetiracetam may increase the sensitivity of glioblastoma cells to temozolomide, though this finding has not yet changed prescribing guidelines on its own.
One side effect deserves careful attention: behavioral changes. Some patients and caregivers describe increased irritability, emotional volatility, and mood swings after starting this medication - a reaction sometimes called Keppra rage. These changes can be subtle at first. If you notice a clear personality shift or increased agitation after starting or adjusting the dose, report it to the care team promptly. Dose adjustment or switching to a different agent often resolves the problem. This is especially important in patients already experiencing personality and behavioral changes related to tumor location or other treatments, where medication-induced changes can be difficult to distinguish from tumor effects.
Valproic acid
Valproic acid is a broad-spectrum antiseizure drug with years of use in brain tumor patients. Some research suggests it may have mild antitumor properties. However, it inhibits certain liver enzymes and can interact with temozolomide in ways that complicate dosing. It also carries a higher risk of liver changes, weight gain, and hair thinning than levetiracetam. It is not a first-choice agent at most GBM centers but may be considered in specific situations where other options are not suitable.
Lacosamide and lamotrigine
These are newer antiseizure agents that also do not induce liver enzymes. They are increasingly used in brain tumor patients - particularly when levetiracetam causes significant behavioral effects. They have different tolerability profiles and may suit patients for whom the first-line option was not well tolerated. The best choice depends on the patient's seizure type, other medications, and overall treatment context.
Older enzyme-inducing drugs
Phenytoin, carbamazepine, and oxcarbazepine speed up the liver's metabolism of many drugs, including some chemotherapy agents and dexamethasone. If a patient was placed on one of these older drugs before the brain tumor was diagnosed, the care team should review whether switching to a non-enzyme-inducing alternative is appropriate before chemotherapy begins.
What if seizures continue despite medication?
Refractory seizures - those that do not respond adequately to the first medication tried - affect a portion of GBM patients. Adding a second antiseizure agent, adjusting the dose, or switching to a different drug are the usual next steps. It is also important to reassess whether the tumor has progressed. New or worsening seizures can signal tumor growth or treatment-related inflammation, which need different treatment approaches and look different on imaging. A thorough imaging review is often the right starting point before changing the antiseizure plan.
In some cases, additional tumor-directed treatment may reduce seizure burden. Focused radiation, repeat surgery, or laser ablation can help when the seizure focus overlaps with accessible tumor tissue. This is a specialist-level decision requiring detailed imaging and electroencephalography (EEG) data. If you are uncertain whether the current plan reflects the full range of available options, you can consult the Art of Healing Cancer team on what your treatment options actually look like before committing to a long-term approach.
Non-drug strategies that may reduce seizure frequency
Medication does the heavy lifting in seizure control, but several lifestyle factors can raise or lower the threshold at which a seizure occurs. Sleep deprivation, high stress, alcohol consumption, fever, and missed medication doses are key seizure triggers for brain tumor patients.
- Sleep: Sleep deprivation is one of the most reliable seizure triggers across all epilepsy types. For GBM patients already managing treatment-related fatigue, this is a practical challenge. Consistent sleep-wake timing - even when nighttime sleep is fragmented - can help reduce seizure risk. Caregivers managing the patient's medication schedule alongside their own exhaustion will find useful strategies in our article on sleep disruption during glioblastoma treatment. For sleep and stress support during treatment, Ayurnomics Sleep and Stress products can help as part of your full medical plan.
- Stress: Chronic psychological stress keeps your nervous system tense and on high alert. Gentle strategies - slow breathing exercises, short guided relaxation sessions, or light outdoor walks - can help lower background stress without overtaxing someone in active treatment.
- Alcohol: Even small amounts of alcohol can lower the seizure threshold. The standard guidance for any patient on antiseizure medication is to avoid alcohol entirely during treatment.
- Fever and illness: Fever reliably raises seizure risk. Treating fever promptly and reporting new infections early - particularly in patients who are immunocompromised from chemotherapy - is important for seizure prevention as well as direct health management.
- Medication timing: Missing a dose of antiseizure medication is one of the most common causes of breakthrough seizures. A weekly pill organizer or phone alarm reduces the chance of a lapse. If vomiting or illness makes oral medication difficult to keep down, the care team needs to know immediately - levetiracetam can be given intravenously with equivalent effectiveness when needed.
Driving and everyday safety
A glioblastoma diagnosis - or a first seizure - triggers mandatory driving restrictions in most countries and US states. The rules vary by jurisdiction and become more complex when the underlying cause is a brain tumor. Our full guide on driving safety and legal restrictions after a glioblastoma diagnosis covers what the rules typically require and what to tell an employer or insurer.
Beyond driving, everyday safety adjustments reduce risk. These include not bathing alone without someone nearby, staying away from heights and ladders, and helping family members and colleagues recognize what a focal seizure looks like so they can respond calmly. A written first-aid plan shared with household members - covering what to do, what not to do, and when to call for help - reduces chaos when it is needed most.
Tracking seizures and knowing when to escalate
A brief seizure log - noting the date, time, duration, and type of episode - gives the care team information they cannot gather from clinic visits alone. Many caregivers keep a running note on their phone and share it at each appointment. Any change in seizure pattern, including new types of episodes, increased frequency, or longer recovery time afterward, should prompt an urgent call to the team rather than a wait-and-see approach. These changes may indicate tumor progression or a need to adjust medication before the next scheduled visit.
If a seizure lasts more than five minutes, if multiple seizures occur without full recovery between them, or if the person does not return to their usual baseline within 30 minutes after the episode ends, this is a medical emergency. Call emergency services rather than waiting.
When to talk to your doctor
Contact the neuro-oncology or neurology team before adjusting any antiseizure medication dose, stopping a medication, or adding any new supplement or over-the-counter product - several interact with antiseizure agents and with chemotherapy in ways that are not always obvious. Contact the team urgently if new seizure types appear, if seizure frequency increases, or if behavioral changes develop after starting or changing an antiseizure medication. Call emergency services if any seizure lasts longer than five minutes.
If you want an independent review of the current antiseizure plan as part of a broader second opinion on the overall treatment approach, you can upload imaging and clinical records through the Glioblastoma Center patient-journey form and request a remote review by the team.
This article is for general information and is not a substitute for medical advice. Always consult your oncologist or care team about your specific situation.