Generic Name: phenobarbital (FEE noe BAR bi tal)Brand names: Solfoton, Luminal
Phenobarbital is in a group of drugs called barbiturates (bar-BIT-chur-ates). Phenobarbital slows the activity of your brain and nervous system.
Phenobarbital is used to treat or prevent seizures. It is also used short-term to treat insomnia, or as a sedative before surgery.
Phenobarbital may also be used for other purposes not listed in this medication guide.
Some people using this medicine have engaged in activity such as driving, eating, or making phone calls and later having no memory of the activity. If this happens to you, stop taking phenobarbital and talk with your doctor about another treatment for your sleep disorder.Do not use phenobarbital without telling your doctor if you are pregnant. It could cause harm to the unborn baby. Use an effective form of birth control, and tell your doctor if you become pregnant during treatment. Phenobarbital can make birth control pills less effective. Ask your doctor about using a non-hormone method of birth control (such as a condom, diaphragm, spermicide) to prevent pregnancy while taking phenobarbital. Phenobarbital may be habit-forming and should be used only by the person it was prescribed for. Phenobarbital should never be shared with another person, especially someone who has a history of drug abuse or addiction. Keep the medication in a secure place where others cannot get to it.
Some people using this medicine have engaged in activity such as driving, eating, or making phone calls and later having no memory of the activity. If this happens to you, stop taking phenobarbital and talk with your doctor about another treatment for your sleep disorder.Do not take this medication if you are allergic to phenobarbital, or if you have porphyria.
If you have any of these other conditions, you may need a dose adjustment or special tests to safely take phenobarbital:
severe asthma, chronic obstructive pulmonary disorder (COPD), or other breathing disorder;
an adrenal gland disorder, such as pheochromocytoma;
a history of depression, mental illness, or suicide attempt; or
a history of drug or alcohol addiction.
Take this medication exactly as it was prescribed for you. Do not take the medication in larger amounts, or take it for longer than recommended by your doctor. Follow the directions on your prescription label.Take phenobarbital only when you are getting ready for several hours of sleep. You may fall asleep very quickly after taking the medicine. Take this medicine with a full glass of water.
Measure the liquid form of phenobarbital with a special dose-measuring spoon or cup, not a regular table spoon. If you do not have a dose-measuring device, ask your pharmacist for one.
If you are taking this medicine to treat insomnia, take it only at bedtime. Do not use phenobarbital for longer than 2 weeks to treat insomnia, unless your doctor has told you to.
Do not change your dose of phenobarbital without your doctor's advice. Tell your doctor if the medication does not seem to work as well in treating your condition.If you are taking phenobarbital to treat seizures, keep taking the medication even if you feel fine. You may have increased seizures or withdrawal symptoms if you stop using phenobarbital suddenly. You will need to use less and less before you stop the medication completely. Store phenobarbital at room temperature away from moisture and heat.
Keep track of how many pills have been used from each new bottle of this medicine. Phenobarbital is a drug of abuse and you should be aware if any person in the household is using this medicine improperly or without a prescription.
See also: Phenobarbital dosage in more detail
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and take the medicine at your next regularly scheduled time. Do not take extra medicine to make up the missed dose.
Overdose symptoms may include slow or shallow breathing, blurred vision, extreme drowsiness, urinating less than usual or not at all, feeling light-headed, or fainting.
Avoid using other medicines that make you sleepy (such as cold medicine, sleeping pills, pain medication, muscle relaxers, and medicine to treat depression or anxiety). They can add to sleepiness caused by phenobarbital.Avoid drinking alcohol. It can increase some of the side effects of phenobarbital.
restless muscle movements in your eyes, tongue, jaw, or neck;
slow heartbeat, shallow breathing;
feeling light-headed, fainting;
a fever or a sore throat;
sores in your mouth;
easy bruising or bleeding; or
broken blood vessels under your skin.
Less serious side effects may include:
drowsiness or dizziness;
problems with memory or concentration;
excitement, irritability, aggression, or confusion (especially in children or older adults);
loss of balance or coordination;
"hangover" effect (drowsiness the day after a dose).
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
Usual Adult Dose for Sedation:
Oral, IV, or IM: 30 to 120 mg/day orally in 2 to 3 divided doses.Maximum of 400 mg/day.Preoperative sedation: 100 to 200 mg IM 60 to 90 minutes before surgery.
Usual Adult Dose for Insomnia:
Oral: 100 to 200 mg with a maximum of 400 mg/day.IM or IV: 100 to 320 mg with a maximum duration of 2 weeks.
Usual Adult Dose for Seizures:
Status Epilepticus: Loading dose IV: 10-20 mg/kg; may repeat dose in 20-minute intervals as needed (maximum total dose: 30 mg/kg)Anticonvulsant Maintenance dose: Oral or IV(Note: Maintenance dose usually starts 12 hours after loading dose):1 to 3 mg/kg/day in 1 to 2 divided doses
Usual Pediatric Dose for Seizures:
Status Epilepticus: Loading dose IV:Less than 1 month:15-20 mg/kg in a single or divided dose; may repeat doses of 5-10 mg/kg every 15-20 minutes as needed (maximum total dose: 40 mg/kg) 1 month to 12 years: 15-20 mg/kg (maximum: 1000 mg/dose); may repeat dose after 15 minutes as needed (maximum total dose: 40 mg/kg)Anticonvulsant Maintenance dose: Oral or IVNote: Maintenance dose usually starts 12 hours after loading dose:Less than 1 month: 3-4 mg/kg/day given once daily; assess serum concentrations; increase to 5 mg/kg/day if needed (usually by second week of therapy)Greater than or equal to 1 month but less than 1 year: 5-6 mg/kg/day in 1-2 divided dosesGreater than or equal to 1 year but less than 5 years: 6 to 8 mg/kg/day orally in 1 to 2 divided dosesGreater than or equal to 5 years up to 12 years: 4 to 6 mg/kg/day orally in 1 to 2 divided dosesGreater than 12 years: 1 to 3 mg/kg/day in 1 to 2 divided doses
Usual Pediatric Dose for Sedation:
1 to 12 years: Sedation: 8 to 32 mg orally.Preoperative sedation: 1 to 3 mg/kg IM or IV.
Usual Pediatric Dose for Insomnia:
Greater than or equal to 1 year but less than 12 years: 3 to 5 mg/kg IM, IV, or subcutaneously once a bedtime.
Usual Pediatric Dose for Hyperbilirubinemia:
Less than 12 years: 3 to 8 mg/kg/day orally in 2 to 3 divided doses.Maximum Dose: 12 mg/kg/day
Tell your doctor about all other medicines you use, especially:
doxycycline (Adoxa, Doryx, Mondox, Oracea, Vibramycin, and others);
other seizure medications such as divalproex (Depakote), phenytoin (Dilantin), or valproic acid (Depakene);
an MAO inhibitor such as isocarboxazid (Marplan), phenelzine (Nardil), rasagiline (Azilect), selegiline (Eldepryl, Emsam), or tranylcypromine (Parnate);
griseofulvin (Grisactin, Fulvicin PG, Grifulvin V);
birth control pills or estrogen hormone replacement, including estrogen (Premarin), estradiol (Estrace, Femtrace, and others), progesterone (Progest, Prometrium), and others;
steroids such as prednisone (Orasone, Deltasone), prednisolone (Prelone, Delta Cortef), methylprednisolone (Medrol), and others.
This is not a complete list and there may be other drugs that can interact with phenobarbital. Tell your doctor about all the prescription and over-the-counter medications you use. This includes vitamins, minerals, herbal products, and drugs prescribed by other doctors. Do not start using a new medication without telling your doctor.