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By Medicover Hospitals / 11 March 2021
Home | Medicine | Phenobarbital
  • Phenobarbital is a barbiturate. The drug reduces brain and nervous system activity. It is used for treating or preventing seizures. The medication is also used as a sedative in the short term to help you relax.
    1. Phenobarbital Uses
    2. Phenobarbital Side effects
    3. Precautions
    4. Interactions
    5. Dosage
    6. Phenobarbital Storage
    7. Phenobarbital vs Diazepam
    8. Frequently Asked Questions

    Phenobarbital Uses

  • To control seizures, this medication is used alone or in combination with other medications. Controlling and reducing seizures allows you to do more of your daily activities, lowers your risk of harm when you lose consciousness, and lowers your risk of a potentially fatal condition characterized by frequent, repeated seizures. Phenobarbital is from the barbiturate anticonvulsants and hypnotics class of drugs. It functions by regulating the abnormal electrical activity in the brain that occurs during a seizure. This medication is also used for a short period of time (usually no more than two weeks) to help calm you or help you sleep when you are anxious. It causes c by affecting specific parts of the brain.
  • How to take

  • Phenobarbital is available as a tablet and an elixir (liquid) to be taken orally. It's typically taken one to three times per day. Follow the directions on your prescription label exactly, and ask your doctor or pharmacist to explain any parts you don't understand. Take the phenobarbital exactly as prescribed.
  • If you take phenobarbital for an extended period of time, it may no longer control your symptoms as well as it worked at the beginning of your treatment. Discuss how you are feeling during your treatment with your doctor.
  • Phenobarbital has the potential to become addictive. Do not take a higher dose, take it more frequently, or take it for a longer period of time than your doctor has prescribed.
  • Do not discontinue phenobarbital without first consulting your doctor. If you stop taking phenobarbital abruptly, you may experience withdrawal symptoms such as anxiety, muscle twitching, uncontrollable shaking of a part of your body, weakness, dizziness, changes in vision, nausea, vomiting, seizures, confusion, difficulty falling or staying asleep, or dizziness or fainting when rising from a lying position. Your doctor will gradually reduce your dose.
  • Phenobarbital Side Effects

    • Drowsiness
    • Headache
    • Dizziness
    • Excitement (especially in children)
    • Nausea
    • Vomiting
    • Slowed breathing
    • Difficulty breathing
    • Swelling of the eyes, lips, or cheeks
    • Rash
    • Blisters
    • Peeling skin
    • Fever
    • Confusion


  • Before taking phenobarbital, inform your doctor or pharmacist if you are allergic to it, other barbiturates, anti-seizure medications, or any other allergies. Inactive ingredients present in this product may cause allergic reactions or other problems.
  • Tell your doctor or pharmacist about your medical history, especially if you have any of the following: certain hormone problems (adrenal disease such as Addison's disease), liver problems, kidney problems, lung problems.
  • This liquid form may contain alcohol or sugar. If you have diabetes, alcoholism, liver disease, or any other condition that requires you to limit or avoid these substances in your diet, proceed with caution.
  • Older adults may be more sensitive to the drug's side effects, particularly drowsiness and dizziness. Drowsiness, confusion, and dizziness can increase the likelihood of a fall.
  • Children may be more sensitive to the drug's side effects. In young children, this drug can often cause excitement rather than drowsiness.
  • This medication should not be used while pregnant. It can harm an unborn child. However, because untreated seizures are a serious condition that can harm both pregnant women and their unborn child, do not stop taking this medication unless your doctor tells you to. If you are planning a pregnancy, consult your doctor immediately about the benefits and risks of using this medication during pregnancy. Because birth control pills, patches, implants, and injections may not work when combined with this medication, consult your doctor about reliable forms of birth control.
  • This medication is excreted in breast milk and may cause excessive sleepiness or feeding difficulties in nursing infants. Before breastfeeding, consult your doctor.
  • This medication may cause a decrease in your folic acid and vitamin K levels, increasing your risk of spinal cord defects. As a result, consult your doctor to ensure that you are getting enough folic acid and vitamin K. Infants born to mothers who used this medication during pregnancy may exhibit symptoms such as fussiness, shaking, or bleeding. If you notice any of these symptoms in your newborn, contact your doctor right away.
  • Interactions

  • Darunavir, etravirine, orlistat, and rilpivirine are some products that may interact with this medication.
  • Other medications can interfere with the removal of phenobarbital from your body, which can have an impact on how well it works.
  • This medication can speed up the removal of other medications from your body, which may impair their effectiveness. Artemether/lumefantrine, asunaprevir, atazanavir, boceprevir, cobicistat, lurasidone, ranolazine, sofosbuvir, sorafenib, voriconazole, and certain calcium channel blockers such as felodipine/nimodipine are among the drugs affected.
  • If this medication is combined with other medications that cause drowsiness or breathing problems, the risk of serious side effects (such as slow/shallow breathing or severe drowsiness/dizziness) may be increased. Tell your doctor or pharmacist if you are taking any other medications, including opioid pain relievers (codeine, hydrocodone), alcohol, marijuana (cannabis), other sleep or anxiety medications (alprazolam, lorazepam, zolpidem), muscle relaxants (carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine).
  • Overdose

  • If someone has taken an overdose of this medicine and has serious symptoms such as passing out or trouble breathing, seek medical advice. Never take more than what is prescribed to you by your doctor.
  • Missed Dose

  • If you forget to take any dose or by mistake miss a dose, take it as soon as you remember it. If it is already the time for the next dose, skip the forgotten dose. Take your next medicine at the regular time schedule. Do not double the dose.
  • Storage

  • The medicine should not come in direct contact with heat, air, and light may damage your medicines. Exposure to medicine might cause some harmful effects or serious side effects. The medicine must be kept in a safe place and out of children’s reach.
  • Phenobarbital vs Diazepam

    Phenobarbital is a barbiturate. Phenobarbital reduces brain and nervous system activity. Diazepam, originally marketed as Valium, is a benzodiazepine anxiolytic medication.
    Phenobarbital is a medication used for preventing seizures. It is commonly used to treat anxiety, seizures, alcohol withdrawal syndrome, benzodiazepine withdrawal syndrome, muscle spasms, difficulty sleeping, and restless legs syndrome.
    Phenobarbital is more potent when compared to diazepam. Diazepam is easier to titrate.

    Frequently Asked Questions:

    Phenobarbital is used for controlling seizures. The medication is also used for relieving anxiety.
    To maintain sedation and alleviate anxiety, tension, and apprehension you can take 30 to 120 mg/day PO, divided into two to three doses. In debilitated patients, the manufacturer recommends a lower dose.
    Phenobarbital can be given as an injection, a liquid elixir, or as tablets. Each has its own rate of action and recommended dosages. Tablets or elixirs start working in about 60 minutes and last for 10 to 12 hours, depending on the dosage and individual metabolism.
    The total daily dose of phenobarbital is then divided into three to four divided doses, not to exceed 600 mg per day. If withdrawal symptoms appear on the first day of treatment, a loading dose of 100 to 200 mg phenobarbital may be administered intravenously (IM) in addition to the oral dose.
    Phenobarbital is used to treat infants (ages 0 to 1 year) who have any type of seizure disorder, as well as other children who have generalized, partial, or febrile seizures. It's also used to treat status epilepticus (seizures lasting greater than 15 minutes).
    As your body adjusts to the medication, you may experience dizziness, drowsiness, excitement, headache, tiredness, loss of appetite, nausea, or vomiting. Notify your doctor or pharmacist right away if any of these side effects persist or worsen.
    Effects on the musculoskeletal system: Chronic phenobarbital use is linked to an increased risk of osteoporosis, decreased bone mineral density, increased bone fractures, and palmar fibromatosis, which is characterized by a thickening and tightening of the tissue beneath the skin in the hands.
    Phenobarbital increases the risk of depression in epileptic patients and should be avoided whenever clinically possible, especially in patients with a personal or family history of affective disorder.


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