Worst Pills, Best Pills

An expert, independent second opinion on more than 1,800 prescription drugs, over-the-counter medications, and supplements

Drug Profile

The information on this site is intended to supplement and enhance, not replace, the advice of a physician who is familiar with your medical history. Decisions about your health should always be made ONLY after detailed conversation with your doctor.

Limited Use [what does this mean?]
Generic drug name: phenobarbital (fee noe BAR bi tal)
Brand name(s): LUMINAL, SOLFOTON
GENERIC: available FAMILIES: Drugs for Epilepsy, Barbiturates
Find the drug label by searching at DailyMed.

Pregnancy and Breast-feeding Warnings [top]

Pregnancy Warning

A number of reports suggest an association between the use of phenobarbital by women with epilepsy and malformations in their infants, including spina bifida and heart defects. Taking more than one drug for epilepsy increases the risk. Tell your doctor if you are pregnant or thinking of becoming pregnant before you take this drug.

Breast-feeding Warning

Phenobarbital is excreted in human milk. Because of the potential for serious adverse effects in nursing infants, you should not take this drug while nursing.

Safety Warnings For This Drug [top]

If you are currently taking zolpidem and develop complex sleep behaviors, discontinue the drug immediately and seek medical help.

Otherwise, if you have been taking zolpidem for awhile, do not stop taking this drug suddenly because it may cause drug-induced dependence. Instead, work with your doctor to create a schedule to stop it gradually to avoid withdrawal reactions (including stomach cramps, vomiting, nervousness and panic attacks).

Facts About This Drug [top]

Phenobarbital is of limited benefit to older adults because it is addictive and has potentially serious adverse effects. You should not be taking it to promote sleep, relieve nervousness or anxiety, lower blood pressure, or reduce pain. Like other barbiturates, it is commonly misused as a painkiller, despite the fact that it can actually increase your sensation of, and reaction to, pain. You should only be taking phenobarbital to control convulsions (seizures). For this purpose, you can take...

Phenobarbital is of limited benefit to older adults because it is addictive and has potentially serious adverse effects. You should not be taking it to promote sleep, relieve nervousness or anxiety, lower blood pressure, or reduce pain. Like other barbiturates, it is commonly misused as a painkiller, despite the fact that it can actually increase your sensation of, and reaction to, pain. You should only be taking phenobarbital to control convulsions (seizures). For this purpose, you can take it at doses well below those that cause you to go to sleep.

If your kidney or liver function is impaired, you need to take less than the usual adult dose of phenobarbital. Phenobarbital causes liver cancer in mice and rats.

Before You Use This Drug [top]

Do not use if you have or have had:

  • porphyria
  • pregnancy or are breast-feeding

Tell your doctor if you have or have had:

  • allergies to barbiturates
  • severe anemia
  • asthma or other breathing difficulties
  • diabetes
  • liver problems
  • history of drug abuse or dependence
  • abnormally increased and sometimes uncontrollable activity or muscular movements
  • overactive thyroid (hyperthyroidism)
  • adrenal gland problems
  • mental depression or suicidal tendencies
  • pain (acute or chronic)
  • kidney problems
  • weakness or feebleness

Tell your doctor about any other drugs you take, including aspirin, herbs, vitamins, and other nonprescription products.

When You Use This Drug [top]

  • Have regular visits with your doctor to check on your progress.
  • Do not suddenly stop taking this drug without checking with your doctor to find out if you need to taper off.
  • Until you know how you react to this drug, do not drive or perform other activities requiring alertness. Phenobarbital may cause drowsiness, dizziness, and lightheadedness.
  • Do not drink alcohol or use other drugs that can cause drowsiness.
  • If physical or psychological dependence is suspected, check with your doctor.
  • Get emergency help at once if you suspect an overdose.
  • If taking oral contraceptives, use another or additional birth control method.

How to Use This Drug [top]

  • If you miss a dose, take it as soon as you remember, but skip it if it is almost time for the next dose. Do not take double doses.
  • Do not share your medication with others.
  • Take the drug at the same time(s) each day.
  • Do not increase the dose if the drug seems ineffective without checking with your doctor first.
  • If you stop taking this medication, remember that adverse effects can still last for several weeks or months.
  • Extended-release form: Swallow capsule or tablet whole.
  • Store at room temperature with lid on tightly. Do not store in the bathroom. Do not expose to heat, moisture, or strong light. Keep out of reach of children.

Interactions with Other Drugs [top]

The following drugs, biologics (e.g., vaccines, therapeutic antibodies), or foods are listed in Evaluations of Drug Interactions 2003 as causing “highly clinically significant” or “clinically significant” interactions when used together with any of the drugs in this section. In some sections with multiple drugs, the interaction may have been reported for one but not all drugs in this section, but we include the interaction because the drugs in this section are similar to one another. We have also included potentially serious interactions listed in the drug’s FDA-approved professional package insert or in published medical journal articles. There may be other drugs, especially those in the families of drugs listed below, that also will react with this drug to cause severe adverse effects. Make sure to tell your doctor and pharmacist the drugs you are taking and tell them if you are taking any of these interacting drugs:

AGENERASE, alcohol, amprenavir, chlorpromazine, COUMADIN, CRYSTODIGIN, cyclosporine, DECADRON, delavirdine, DEPAKENE/DEPAKOTE, dexamethasone, digitoxin, divalproex/valproic acid, doxycycline, DURAQUIN, ELIXOPHYLLIN, FLAGYL, FORTOVASE, GABITRIL, HEXADROL, INVIRASE, LOPRESSOR, methoxyflurane, metoprolol, metronidazole, nelfinavir, NEORAL, NORVIR, oral contraceptives, oxcarbazepine, PENTHRANE, QUINAGLUTE DURA-TABS, QUINIDEX, quinidine, RESCRIPTOR, ritonavir, SANDIMMUNE, saquinavir, SLO-BID, THEO-24, theophylline, THORAZINE, tiagabine, TOPROL XL, TRILEPTAL, VIBRAMYCIN, valproic acid, VIRACEPT, warfarin.

Adverse Effects [top]

Call your doctor immediately if you experience:

  • confusion
  • mental depression
  • unusual excitement
  • sore throat and/or fever
  • skin rash or hives
  • swelling of eyelids, face, or lips
  • wheezing or chest tightness
  • red, thickened, or scaly skin
  • hallucinations
  • unusual tiredness or weakness
  • bleeding sores on lips
  • chest pain
  • muscle or joint pain
  • painful sores, ulcers, or white spots in mouth
  • unusual bleeding or bruising
  • yellow eyes or skin
  • bone pain, tenderness, or aching
  • appetite loss
  • weight loss

Call your doctor if these symptoms continue:

  • clumsiness or unsteadiness
  • dizziness or lightheadedness
  • drowsiness
  • “hangover” feeling
  • anxiety or nervousness
  • constipation
  • faintness
  • headache
  • irritability
  • nausea or vomiting
  • nightmares or trouble sleeping

Call your doctor if these symptoms continue after you stop taking this drug:

  • anxiety or restlessness
  • muscle twitching
  • hand trembling
  • weakness
  • dizziness
  • vision problems
  • nausea
  • vomiting
  • trouble sleeping
  • increased dreaming or nightmares
  • faintness
  • lightheadedness
  • convulsions
  • hallucinations

Signs of overdose:

  • severe confusion
  • decrease in or loss of reflexes
  • severe drowsiness
  • fever
  • low body temperature
  • shortness of breath or troubled breathing
  • slow heartbeat
  • slurred speech
  • staggering
  • unusual eye movements
  • severe weakness

If you suspect an overdose, call this number to contact your poison control center: (800) 222-1222.

Periodic Tests[top]

Ask your doctor which of these tests should be done periodically while you are taking this drug:

  • complete blood count
  • liver function tests
  • kidney function tests
  • blood levels of phenobarbital (when used as an anticonvulsant)
  • folate concentrations
  • bone marrow function

last reviewed June 30, 2021