Taking too much Keppra (levetiracetam) most commonly causes heavy drowsiness and respiratory depression, meaning your breathing slows to a dangerous degree. In most reported cases, people recover fully with supportive medical care, but a large overdose can require intubation and intensive monitoring. The severity depends on how much you took, whether you already take the drug regularly, and whether you have other health conditions.
The Most Common Overdose Symptoms
The hallmark of a Keppra overdose is extreme sedation. In one well-documented case, a 38-year-old woman who ingested thirty grams (sixty 500 mg tablets) arrived at the emergency department in a near-unconscious state and had to be placed on a breathing machine because her respiratory drive had dropped so significantly. Her reflexes were also markedly reduced. Beyond sedation, overdose can produce anxiety, restlessness, irritability, irregular heartbeat, shallow or labored breathing, shaking, and pale or bluish skin around the lips and fingernails.
What’s notable about Keppra compared to many other seizure medications is that it has a relatively wide safety margin. The body clears it quickly, with a half-life of about six to eight hours in adults (slightly longer in older adults whose kidneys work less efficiently). This means that even after a significant overdose, drug levels drop fairly fast once the acute danger is managed.
Behavioral and Psychiatric Effects
Keppra is well known for causing mood and behavioral changes even at normal doses. In clinical trials, more than 13% of patients experienced agitation, hostility, anxiety, depression, or emotional instability. In children, the rate is even higher: one review found that about 30% of pediatric patients developed behavioral side effects, with aggression, hostility, and anxiety being the most common.
Taking too much amplifies these risks. The drug appears to affect a brain receptor system similar to the one targeted by PCP (a dissociative drug), which may explain why some people experience intense agitation or even psychosis-like episodes. The reassuring finding is that these psychiatric effects are transient. Multiple case studies confirm that behavioral disturbances resolve quickly once the drug is reduced or stopped, with patients returning to their normal baseline.
Interestingly, some research suggests that developing severe behavioral side effects isn’t purely dose-dependent. In one series of 553 patients, the 6.9% who had to stop Keppra due to intolerable behavioral symptoms had actually been on lower doses than those who tolerated the drug fine. This points to individual susceptibility rather than a simple “more drug equals more problems” relationship.
How Children Are Affected
Accidental overdoses in young children tend to have a milder course. An 11-year review of 82 Keppra ingestions in children under six found that about 80% showed no symptoms at all. Around 20% developed drowsiness or unsteady movement, and outcomes were overwhelmingly minor. There were no deaths and no cases classified as having major outcomes. Nearly all children (97.6%) were treated and sent home from the emergency department.
One notable finding: children who had never taken Keppra before were six times more likely to develop symptoms than children already on the medication, even when the drug-naive children ingested a smaller dose. This suggests the body builds some tolerance to the sedating effects with regular use.
Kidney Damage and Organ Effects
Keppra is primarily cleared through the kidneys, and in rare cases, overdose has caused acute kidney injury. At least one published case required dialysis to manage both the drug levels and the kidney damage. The mechanism isn’t fully understood, but it may involve inflammation in the kidney tissue (interstitial nephritis). People with pre-existing conditions like diabetes, high blood pressure, or active infections face a higher risk of kidney complications.
For people who already have impaired kidney function, the drug clears more slowly, which means even a modest excess dose can build up to problematic levels. Older adults are particularly vulnerable here, since kidney efficiency naturally declines with age.
Can a Keppra Overdose Be Fatal?
Fatal outcomes from Keppra alone are extremely rare. A review of postmortem data from North Carolina identified only two deaths where a pathologist attributed the cause to levetiracetam, and both cases involved significant contributing factors. One was a 48-year-old man with an enlarged heart and coronary artery disease. The other was a 56-year-old woman who had multiple drugs in her system along with congestive heart failure and chronic obstructive pulmonary disease. In both cases, the pre-existing heart and lung conditions likely played a critical role.
Prior to those cases, the medical literature had only reported overdoses in which people survived with respiratory support. The woman who took approximately 30 grams recovered because her breathing was supported in time. The core danger of a large Keppra overdose isn’t direct organ toxicity so much as the risk of your breathing slowing or stopping before you receive medical help.
What Happens at the Hospital
There is no antidote for a Keppra overdose. Treatment is entirely supportive, meaning the medical team focuses on keeping you breathing, monitoring your heart rhythm and vital signs, and waiting for the drug to clear your system. If the overdose is recent, stomach emptying or other methods to limit absorption may be used.
Dialysis is an effective option in serious cases. A standard four-hour session removes roughly 50% of the drug from the bloodstream, which can significantly speed recovery. This is especially useful for patients with poor kidney function who can’t clear the drug on their own at a normal rate.
Given the six-to-eight-hour half-life, most people see meaningful improvement within 12 to 24 hours as drug levels fall. Recovery from even severe overdoses has generally been described as rapid once supportive care is in place.
Extra Dose vs. Massive Overdose
If you accidentally doubled your dose, the experience will be very different from a massive intentional overdose. An extra therapeutic dose might cause increased drowsiness, some dizziness, or mild irritability, but it’s unlikely to cause respiratory depression or require emergency intervention. The symptoms described above, like breathing difficulty and loss of consciousness, are associated with ingestions many times the prescribed amount.
That said, your individual risk depends on your kidney function, your age, what other medications you take, and how long you’ve been on Keppra. Combining Keppra with other sedating drugs, alcohol, or medications that slow breathing increases the danger of any excess dose considerably.