How do you take Phenobarbital?

For adults with epilepsy, the usual dose is 60 mg to 180 mg once daily at bedtime, as prescribed by your doctor. Swallow the tablet with water — you can take it with or without food. Do not suddenly stop taking this medicine without your doctor's advice, as this can cause dangerous seizures.

What are the side effects of Phenobarbital?

Feeling very sleepy or drowsy, dizziness, feeling confused or slow in thinking, poor coordination or unsteady walking, mild headache

Who should not take Phenobarbital?

People allergic to phenobarbital or other barbiturates, people with severe liver or kidney disease, people with porphyria (a rare blood condition), people with severe breathing problems, and people with a history of drug or alcohol addiction. Do not give to anyone without a doctor's prescription.

Prescription

Anticonvulsant (Barbiturate)

Phenobarbital

Q: What is Phenobarbital used for?

Epilepsy (seizures/convulsions), fits in children, anxiety, difficulty sleeping, status epilepticus (prolonged seizures that won't stop)

Last reviewed June 2026

Who is this for?

What is this drug?

Phenobarbital (also called phenobarbitone) is a medicine that calms down overactive electrical signals in the brain, helping to prevent seizures (convulsions) and also working as a sedative to help people relax or sleep.

What is it used for?

Epilepsy (seizures/convulsions)fits in childrenanxietydifficulty sleepingstatus epilepticus (prolonged seizures that won't stop)

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Epilepsy & Seizures Anxiety & Sleep Problems

How it works

Enhances inhibitory neurotransmission by potentiating GABA-A receptor activity in the central nervous system, increasing chloride channel opening and neuronal hyperpolarization to suppress seizure activity and reduce neuronal excitability.

Prescription Required

You need a doctor's prescription to buy this drug.

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What to watch out for

This is a strictly controlled prescription drug — never buy it from roadside sellers or use someone else's prescription, as wrong doses can be life-threatening. Do not stop taking it suddenly on your own, even if you feel better, because sudden withdrawal can trigger very serious seizures. This medicine causes drowsiness, so avoid driving, operating machines, or doing anything dangerous until you know how it affects you.

Common Side Effects

Feeling very sleepy or drowsy
dizziness
feeling confused or slow in thinking
poor coordination or unsteady walking
mild headache

Serious Side Effects

Difficulty breathing or very slow breathing — go to the hospital immediately. Severe skin rash
blistering
or peeling skin — stop the drug and see a doctor at once. Unusual mood changes
thoughts of harming yourself
or extreme confusion need urgent medical attention.

Drug Interactions

Alcohol — never drink alcohol while on this medicine as it can dangerously increase drowsiness and slow your breathing. Contraceptive pills — phenobarbital can make birth control pills less effective, so discuss alternative family planning with your doctor. Other sedatives or sleeping medicines — combining them with phenobarbital can cause dangerously heavy sedation.

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Pregnancy & Breastfeeding Warning

Phenobarbital is NOT safe during pregnancy as it can cause birth defects and bleeding problems in the newborn, and it passes into breast milk — talk to your doctor immediately if you are pregnant, planning to become pregnant, or breastfeeding.

Who Should NOT Take This

People allergic to phenobarbital or other barbiturates
people with severe liver or kidney disease
people with porphyria (a rare blood condition)
people with severe breathing problems
and people with a history of drug or alcohol addiction. Do not give to anyone without a doctor's prescription.

How to Store

Store in a cool, dry place away from direct sunlight and heat — Nigerian weather can be very hot, so avoid storing near windows or in cars. Keep the medicine tightly sealed and far away from children, as even a small overdose can be very dangerous for a child.

For information only — not medical advice. Always talk to a doctor or pharmacist before changing your medication.