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What to know about taking phenobarbital for seizures

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AboutHow it worksEfficacySide effectsConsiderationsOverdoseAlternativesSummary
Phenobarbital can stabilize brain activity and help manage diverse seizure types. There are some side effects, and alternative options are also available.
Medically reviewed by Alexandra Perez, PharmD, MBA, BCGP
Written by Charlotte Parker
Updated on

Phenobarbital is a barbiturate medication that can protect against various types of seizures. In the United States, doctors and healthcare professionals often use it to help treat people with epilepsy.

Besides seizure control, it also has some sedating effects in drug withdrawal. However, the Food and Drug Administration (FDA) does not approve it for this purpose, and it is on the U.S. controlled substance schedule due to its associated risk of misuse, addiction, and overdose.

About phenobarbital

Female smiling looking at her birthday cake that has lit candles and enjoying her birthday after possibly taking phenobarbital for seizures
1215678323Nenad Stojnev/Getty Images

Phenobarbital has been in use for over 100 years to treat seizures in both adults and children.

However, doctors are careful when prescribing this medication as it can make you feel sleepy and dizzy. And, if you use it for a long time, it might become habit-forming.

These side effects can affect your everyday life, but you can help manage them with the right support and advice from a doctor.

How does phenobarbital treat seizures?

Phenobarbital effectively treats partial and generalized seizures by enhancing gamma-aminobutyric acid (GABA), a neurotransmitter that reduces seizure-causing brain activity.

Doctors may prescribe phenobarbital on its own or alongside other seizure medications. It is important to always stick to your prescribed dose.

Altering or stopping phenobarbital without a doctor’s advice may be dangerous.

Is phenobarbital effective?

Phenobarbital is very good at preventing seizures. A 2020 randomized controlled trial showed it to have an 80% success rate in keeping newborns seizure-free.

Like other seizure medications, its effectiveness and side effects need careful monitoring. Healthcare professionals measure its success by looking at how much your seizure frequency reduces and how it affects your daily routine, including managing side effects and maintaining a good quality of life.

What are the side effects?

Understanding the side effects of phenobarbital is crucial for anyone considering or currently using this medication. Some of its unwanted effects are:

  • drowsiness and sedation
  • difficulty breathing
  • dizziness and coordination issues
  • concentration and memory difficulties
  • irritability or depression
  • nausea, vomiting, constipation, and, in rare cases, allergic reaction

Long-term effects can include a change in bone density or skin rashes.

The likelihood and intensity of these side effects can vary from person to person. The key is to balance the seizure control benefits with these potential side effects.

If you are experiencing side effects, it is essential to talk with a doctor about managing them. Together, you can decide whether phenobarbital is the best medication for your condition.

Who should not take phenobarbital?

You should not take phenobarbital if you have:

  • an allergy to barbiturates
  • a history of substance misuse
  • a specific medical condition, like:
    • porphyria
    • severe respiratory problems
    • liver disease
    • kidney disease
    • congenital long QT syndrome

If possible, you should also avoid this medication if you are pregnant or nursing. Additionally, doctors will typically offer alternative medications to those over the age of 65 years, as phenobarbital may not be as effective or safe.

It is important to note that there is a risk of death if you use phenobarbital alongside alcohol or opiates.

Can you overdose on phenobarbital?

It is important to always stick to your prescribed phenobarbital dosage — taking too much may have very serious and sometimes fatal outcomes.

Symptoms of an overdose often include:

  • extreme sleepiness
  • confusion
  • difficulty breathing
  • in severe cases, coma or life threatening conditions

Keep all medications stored securely and out of the reach of children.

If you think you or someone you know has overdosed, it is critical to act fast:

  • Call 911 immediately for emergency help or use text-to-911 services if available in your area.
  • You can also contact the toll-free Poison Control Center at 800-222-1222 for guidance or use their online web chat for service at the Poison Control Center website.
  • Provide details about the medication and when it was ingested.

What should I do if I forget a dose?

If you miss a dose of phenobarbital, and there is only a short time until your next dose, skip the missed dose and continue your regular schedule.

If there is a longer time between doses, take one as soon as you remember, but do not double-dose to make up for the missed one.

Taking phenobarbital on a consistent schedule is essential for seizure control, so you may consider using reminders, like alarms or apps, to keep track. Consult a doctor or healthcare professional if you regularly miss doses.

Are there any alternatives to phenobarbital?

Several alternatives to phenobarbital are available for treating seizures. The choice depends on seizure type, overall health, and how you respond to the treatment.

The table below shows some common alternatives.

MedicationUsesSide effects
levetiracetam (Keppra)tonic-clonic, myoclonic, and partial seizuresfewer side effects, minimal interaction with other medications
carbamazepine (Carbatrol)partial seizures, generalized tonic-clonic seizuresrequires monitoring for blood cell and liver function side effects
lamotrigine (Lamictal)partial, tonic-clonic, and absence seizures• generally well-tolerated
• requires monitoring for skin reactions
valproic acid (Depakene)partial, tonic-clonic, and absence seizures• requires liver function monitoring
• significant side effects, especially in pregnant people
topiramate (Topamax)partial and tonic-clonic seizures and migraine preventionunique side effects like weight loss and tingling sensations
gabapentin (Neurontin)partial seizuresbeneficial for nerve pain
pregabalin (Lyrica)partial seizuresbeneficial for nerve pain

Another option is zonisamide (Zonegran, Zonisade). Doctors may prescribe this medication for partial seizures, but it is not effective on its own, so they will likely prescribe this alongside other medications.

Choosing an alternative medication is highly personalized — doctors base it on your specific needs, seizure types, other health conditions, and your response to the medication.

Consulting with a neurologist or a doctor specializing in epilepsy is necessary to determine the most suitable alternative for your condition.

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Phenobarbital is a key epilepsy medication that helps manage seizures by calming neurotransmitters in the brain. It is effective but needs careful use due to side effects like drowsiness.

In the United States, phenobarbital is on the controlled substance schedule due to its risk of misuse, addiction, and overdose. Regular check-ins with a doctor or healthcare professional are important for the best possible care and to ensure safety.

Although many newer antiseizure treatments are available, phenobarbital remains one of the most effective medications that can help improve your health and life quality when you take it under medical guidance.

Download the free Optum Perks Discount Card to save up to 80% on some prescription medications.

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