Neonatal Seizure Treatment: Phenobarbital vs Levetiracetam and When to Stop

Why Neonatal Seizure Treatment Matters

Seizures are the most common neurological emergency in the newborn period, occurring in roughly one to four per 1,000 live births and far more often in preterm infants. Most are acute and provoked, with hypoxic-ischaemic encephalopathy the leading cause.

Two questions dominate the bedside decision. Which drug should go in first — the century-old barbiturate or a newer agent with a gentler reputation? And once the seizures stop, how long should that drug continue?

Both questions sat on weak evidence for decades. Clinicians reached for phenobarbital largely out of habit, and treatment duration varied widely from one unit to the next. Recent randomised trials, pooled analyses, and a large multicentre cohort have now sharpened the picture on both fronts, which is why this comparison is worth revisiting in depth.

The urgency is not merely academic. A higher electrographic seizure burden has been associated with worse neurodevelopmental outcomes, which is the rationale for treating promptly and effectively. Many neonatal seizures are also subclinical, visible only on EEG, so relying on observed movements alone underestimates the true burden.

That gap between clinical and electrographic seizures shapes how efficacy itself should be judged. A drug that quiets visible movements has not necessarily controlled the underlying electrical seizures, and this distinction runs through the trial evidence that follows.

The Options Compared

Phenobarbital and levetiracetam are the two agents most often weighed as first-line neonatal seizure treatment. Phenobarbital carries the longest track record and the strongest guideline endorsement; levetiracetam has spread through neonatal units on the strength of its safety profile and easy dosing, often off-label.

Levetiracetam’s appeal is both mechanistic and practical. It acts through the synaptic vesicle protein SV2A rather than the sedating GABAergic pathway of the barbiturates, needs no routine serum-level monitoring, and has a wide therapeutic margin. Those features made it attractive long before comparative trials existed, which is precisely why rigorous head-to-head data mattered.

The table below summarises the studies that anchor this review. Every figure was checked against a retrieved source for this synthesis, and sample sizes are the real enrolled numbers rather than modelled estimates.

Seizure Control — How Phenobarbital and Levetiracetam Differ

The headline result comes from NEOLEV2, the first blinded randomised trial to compare the two drugs head-to-head. Phenobarbital led to complete 24-hour seizure freedom in 80% of newborns, against 28% with levetiracetam.

The relative risk of 0.35 (95% CI 0.22–0.56) is large, and the confidence interval sits well clear of no effect. Because this was a randomised, EEG-confirmed, blinded design, the causal reading is legitimate: phenobarbital controlled more seizures than levetiracetam at the doses tested.

One caveat matters. Levetiracetam was dosed at 40 mg/kg, and escalating to 60 mg/kg improved its response by about 7.5 percentage points. The trial therefore cannot exclude a smaller gap at higher levetiracetam doses.

Pooled analyses complicate the simple conclusion. When trials and cohorts are combined, the efficacy difference shrinks and loses significance.

• Across 11 randomised trials (821 neonates), seizure control did not differ significantly between the drugs — RR 1.11 (95% CI 0.79–1.54), with high heterogeneity (I²=88%).
• An earlier synthesis of 10 studies reached the same verdict: no efficacy difference (OR 0.79, 95% CI 0.25–2.44).

Why the divergence? NEOLEV2 is a single, rigorously blinded trial with EEG-confirmed endpoints, while the pooled estimates fold in smaller open-label studies with clinical endpoints that tend to flatter levetiracetam. The honest summary is that the most rigorous single trial favours phenobarbital, while the aggregate evidence reads closer to a draw.

For context, phenobarbital’s own efficacy is not overwhelming. In the older Painter trial it controlled seizures in 43% of newborns — statistically indistinguishable from phenytoin at 45%, with both agents failing in more than half of infants.

This modest ceiling is part of why the field looked for alternatives at all. If phenobarbital controlled every seizure, its sedation and cardiorespiratory effects would matter less. Because it does not, a drug of similar efficacy but a gentler profile becomes an appealing trade rather than a compromise.

Safety and Neurodevelopment — How They Differ

If efficacy is close, safety is where the two drugs clearly part ways. Phenobarbital’s sedative and cardiorespiratory effects are its longstanding drawback, and the pooled data quantify that difference.

In the meta-analysis of 11 randomised trials, levetiracetam was associated with significantly less hypotension (RR 0.28, 95% CI 0.09–0.86) and less respiratory depression (RR 0.36, 95% CI 0.19–0.66). The earlier synthesis found the same pattern of fewer adverse events with levetiracetam.

NEOLEV2 pointed in the same direction, with more adverse effects — mainly hypotension, respiratory depression, and sedation — in the phenobarbital arm, though that difference did not reach significance within the single trial.

The concern that draws most attention is the developing brain itself. Phenobarbital promotes neuronal apoptosis in immature animal models, which has long fuelled interest in alternatives. So far, human neurodevelopmental data have not confirmed a clear clinical penalty.

Pooled Bayley Scales of Infant Development scores did not differ significantly between levetiracetam and phenobarbital in the available studies. Preliminary evidence suggests levetiracetam may be gentler on the developing brain, but the long-term comparative outcome data remain thin and are not yet decisive.

This safety gap is why the current guideline names levetiracetam the preferred second-line agent specifically in neonates with cardiac disorders, where hypotension is least welcome.

In practice the safety calculus shifts by patient. A vigorous term newborn may tolerate phenobarbital’s effects without difficulty, so its efficacy advantage weighs heavily. A ventilated, hypotensive, or cardiac infant sits at the other end, where levetiracetam’s gentler profile can outweigh a modest efficacy gap.

When to Stop Neonatal Seizure Treatment

The second half of neonatal seizure treatment is duration, and here the evidence has shifted decisively toward stopping early. Most neonatal seizures are acute and provoked; once the underlying insult resolves, the seizures usually do too.

The pivotal data come from the Neonatal Seizure Registry. In a comparative-effectiveness study of 303 newborns with acute symptomatic seizures, 64% were still on medication at discharge, reflecting the older reflex to continue.

After adjustment for the propensity to maintain treatment, stopping medication before discharge was not associated with worse functional neurodevelopment or a higher risk of epilepsy at 24 months. Epilepsy-free survival was essentially identical between groups (HR 0.8, 95% CI 0.4–1.5).

That finding rests on the natural history of these seizures. In the same cohort, only 13% of survivors developed post-neonatal epilepsy by 24 months.

Among those who did, the burden was real: about a third had infantile spasms and a third had drug-resistant epilepsy. But the base rate was low enough that maintenance medication offered little preventive value.

Notably, continuing an antiseizure drug did not lower that epilepsy risk. The evidence is consistent that phenobarbital maintenance after acute seizures does not change later seizure or developmental outcomes, so prolonged exposure carries cost without measurable benefit.

Surveys of neonatal practice have documented how variable this decision once was. Prophylactic phenobarbital was often continued for weeks or months on the assumption that it prevented later epilepsy — an assumption the outcome data do not support. Recognising that has allowed many units to shorten exposure without evident harm.

Two practical boundaries deserve emphasis. First, “stop early” applies to acute provoked seizures, not to a neonatal-onset epilepsy syndrome, where an underlying genetic or structural cause means seizures are likely to continue and maintenance therapy is appropriate. Second, an abnormal MRI or interictal EEG on its own is no longer a reason to keep medication going after provoked seizures have resolved.

Where phenobarbital fails to control seizures, escalation rather than duration becomes the issue. A multicentre observational study supports sequential levetiracetam and phenytoin for electrographic seizures that persist after phenobarbital, reflecting how second-line choices are sequenced in practice.

Quality and Consistency of the Evidence

The evidence base for neonatal seizure treatment is uneven across the two clinical questions, and reading it well means grading each strand separately.

• Safety advantage of levetiracetam — moderate to strong. Reduced hypotension and respiratory depression are consistent across randomised trials and pooled analyses, with reasonably tight confidence intervals.
• First-line efficacy — moderate but conflicted. One rigorous blinded trial favours phenobarbital, while pooled estimates show no difference. High heterogeneity (I²=88%) and dose variability limit certainty.
• Early discontinuation — moderate. A large, prospective, multicentre cohort with 24-month follow-up gives reasonably strong observational support, now reinforced by guideline consensus.
• Long-term neurodevelopment by drug — low. Bayley scores show no clear difference, but comparative long-term outcome data are sparse and follow-up is short.
• Optimal levetiracetam dose — low. A dose-response signal exists, but no adequately powered trial has tested higher-dose levetiracetam head-to-head against phenobarbital.

A recurring limitation runs through the first-line literature: many trials used clinical rather than EEG-confirmed seizure endpoints. Because clinical cessation of movements does not reliably indicate electrographic seizure control, those studies may overstate efficacy — a bias that tends to narrow the gap between the drugs.

What the Evidence Does Not Show

Several specific questions remain unresolved, and naming them precisely matters more than a general call for further study.

The discontinuation evidence, though practice-changing, is observational rather than randomised. A randomised trial of phenobarbital versus placebo after seizure resolution closed early owing to low enrolment, so residual confounding cannot be fully excluded.

Finally, the trials are dominated by term infants with hypoxic-ischaemic encephalopathy. How the comparison plays out in preterm neonates, or in seizures from stroke, infection, or metabolic causes, is far less certain.

Access to continuous EEG also shapes what “seizure control” means in practice. Much of the world manages neonatal seizures without it, yet most of the trial evidence comes from EEG-equipped centres. How these findings translate to settings that rely on clinical assessment alone remains an open question.

Practical Implications

The evidence on neonatal seizure treatment supports a defensible default rather than a single correct answer, and the choice can be tailored to the newborn in front of you.

• Phenobarbital remains the evidence-based first-line choice for most acute provoked neonatal seizures, reflecting the only blinded trial and current guideline consensus.
• Levetiracetam is a reasonable first alternative where cardiorespiratory instability makes phenobarbital’s sedation and hypotension especially unwelcome, and it is the preferred second-line agent in neonates with cardiac disease.
• Confirm response with EEG where available, since resolution of visible movements does not guarantee electrographic control.
• Plan for escalation early. More than half of newborns are not fully controlled by a single agent, so a second-line pathway should be ready before it is needed.
• Stop before discharge once acute seizures have resolved and there is no evidence of a neonatal-onset epilepsy syndrome — an abnormal MRI or EEG alone does not justify continuing.

These are framed as what the current evidence supports, not as directives; individual clinical judgement, aetiology, and local protocols still govern the decision.

Evidence Grade and Bottom Line

The bottom line for neonatal seizure treatment is a division of labour between the two drugs and a change of habit on duration.

• For raw seizure control, the best single trial favours phenobarbital; the pooled evidence reads as a tie.
• For safety, levetiracetam is consistently gentler, which shapes its role in fragile and cardiac newborns.
• For duration, most newborns with acute provoked seizures can safely stop medication before going home, because the risk of later epilepsy is low and maintenance does not lower it.