Abstract illustration of the risks of phenobarbital.

Phenobarbital and Drowning: Unraveling the Risks

Theo Raines in Health & Wellness December 2025 • 3 min read.

"A deep dive into a case study that links epilepsy treatment with fatal drowning."

Phenobarbital, a long-standing medication used in the treatment of epilepsy, has been a subject of both praise and scrutiny. While it effectively manages seizures for many, a recent case study brings to light a concerning potential risk: drowning. Understanding this connection is crucial for both patients and healthcare providers.

The case study, documented in Reactions 1711, p252 and published on July 21, 2018, details a patient's tragic death due to drowning, which was found to be secondary to phenobarbital treatment for epilepsy. This raises important questions about the drug's side effects and the precautions necessary for those using it.

This article aims to dissect this case study, providing a comprehensive yet accessible explanation of the factors that link phenobarbital to an increased risk of drowning. We'll explore the drug's mechanism, potential side effects, and necessary safety measures to ensure patient well-being.

The Case Study: A Closer Look

Abstract illustration of the risks of phenobarbital.

The study focuses on a patient who, while undergoing treatment with phenobarbital for epilepsy, tragically died as a result of drowning. Post-mortem toxicology reports revealed that the patient had supra-therapeutic levels of phenobarbital in their system.

Supra-therapeutic levels indicate that the concentration of the drug in the patient's body exceeded the recommended therapeutic range. This is significant because such elevated levels can lead to severe central nervous system (CNS) depression.

CNS depression slows down brain activity, impacting vital functions such as breathing and heart rate.
It can also impair cognitive and motor functions, reducing a person's ability to react quickly and maintain coordination.
This impairment directly contributed to the patient's inability to stay afloat, ultimately leading to drowning.

The author's comment on the case highlights a critical point: while the phenobarbital levels were not high enough to be the sole cause of death, they significantly contributed to the drowning. The CNS depression induced by the drug impaired the patient's ability to stay afloat, turning a potentially survivable situation into a fatal one.

Staying Safe: Precautions and Awareness

The case study serves as a stark reminder of the potential risks associated with phenobarbital and similar medications. While these drugs can be life-saving for those with epilepsy, it's crucial to be aware of the side effects and take necessary precautions. Patients should be closely monitored for signs of CNS depression, and alternative treatments should be considered if adverse effects become too severe. Open communication between patients, caregivers, and healthcare providers is essential for ensuring the safe and effective use of phenobarbital.

About this Article -

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Everything You Need To Know

What is phenobarbital, and why is it relevant in this context?

Phenobarbital is a medication primarily used to treat epilepsy. In this context, its importance lies in its potential to increase the risk of drowning. The case study highlights a tragic incident where a patient on phenobarbital experienced CNS depression, impairing their ability to stay afloat and leading to drowning. This underscores the need to understand the drug's side effects and take appropriate safety measures.

What happened in the case study involving phenobarbital?

The case study details the tragic death of a patient who drowned while undergoing phenobarbital treatment for epilepsy. Post-mortem toxicology revealed supra-therapeutic levels of phenobarbital, meaning the drug concentration in the patient's body exceeded the recommended therapeutic range. This elevated level resulted in Central Nervous System (CNS) depression, which significantly impaired the patient's ability to stay afloat, contributing to their drowning.

What is CNS depression, and how does it relate to the risk of drowning?

CNS depression is a critical factor in the increased drowning risk associated with phenobarbital. It slows brain activity, impacting vital functions such as breathing and heart rate. It also impairs cognitive and motor functions, reducing a person's ability to react quickly and maintain coordination. In the context of water, this impairment can prevent someone from staying afloat, increasing the likelihood of drowning. The case study emphasizes that even though the phenobarbital levels weren't the sole cause of death, the induced CNS depression played a crucial role in the fatal outcome.

What are supra-therapeutic levels of phenobarbital, and why are they important?

Supra-therapeutic levels of phenobarbital refer to drug concentrations in the body that are above the recommended therapeutic range. These elevated levels are significant because they can lead to severe CNS depression. This depression can manifest as slowed brain activity, impacting breathing, heart rate, and impairing cognitive and motor functions. In this specific instance, the patient had supra-therapeutic levels. This impairment contributed to the patient's inability to stay afloat, eventually causing the patient's death by drowning.

What safety measures should be taken when using phenobarbital?

To ensure the safe use of phenobarbital, patients should be closely monitored for signs of CNS depression. Healthcare providers might consider alternative treatments if adverse effects become too severe. Open communication between patients, caregivers, and healthcare providers is essential. Awareness of the potential risks, including drowning, is paramount. The case study serves as a stark reminder of the need for vigilance and proactive measures to mitigate risks associated with phenobarbital use.