Mebaral Side Effects Center

Last updated on RxList: 4/4/2022
Mebaral Side Effects Center

What Is Mebaral?

Mebaral (mephobarbital) is a barbiturate used as a sedative to treat anxiety, tension, and apprehension (dreading or feeling uneasy about what you think may happen). Mebaral is also used to treat seizures. Mebaral is available in generic form.

What Are Side Effects of Mebaral?

Common side effects of Mebaral include:

  •  drowsiness
  • dizziness
  • upset stomach
  • headache
  • memory or thinking problems
  • nervousness
  • agitation
  • nausea, or
  • vomiting

Dosage for Mebaral

The adult dose of Mebaral for sedation is 32 to 100 mg; optimum dose, 50 mg, three to four times daily. The average dose for adults to treat epilepsy is 400 mg to 600 mg daily.

What Drugs, Substances, or Supplements Interact with Mebaral?

Mebaral may interact with blood thinners, doxycycline, griseofulvin, phenobarbital, steroids, phenytoin, divalproex sodium, valproic acid, MAO inhibitors, cold or allergy medicine, narcotics, sleeping pills, muscle relaxers, and medicine for seizures, depression or anxiety. Tell your doctor all medications and supplements you use.

Mebaral During Pregnancy or Breastfeeding

During pregnancy, Mebaral should be used only when prescribed. It may harm a fetus. Since untreated seizures are a serious condition that can harm both a pregnant woman and her unborn baby, do not stop taking this medication unless directed by your doctor. If you are pregnant, or think you may be pregnant, talk to your doctor about using this medication during pregnancy. Birth control pills, patches, implants, and injections may not work if taken with this medication; discuss birth control with your doctor. This medication may lower your folic acid levels, increasing the risk of spinal cord defects. Consult your doctor to make sure you are taking enough folic acid. Prenatal care should include tests for spinal cord defects. Small amounts of this drug pass into breast milk. Consult your doctor before breastfeeding. Withdrawal symptoms may occur if you suddenly stop taking this medication.

Additional Information

Our Mebaral (mephobarbital) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

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.


If you have had a seizure, it means you have epilepsy. See Answer
Mebaral Professional Information


The following adverse reactions and their incidence were compiled from surveillance of thousands of hospitalized patients. Because such patients may be less aware of certain of the milder adverse effects of barbiturates, the incidence of these reactions may be somewhat higher in fully ambulatory patients.

More than 1 in 100 Patients. The most common adverse reactions estimated to occur at a rate of 1 to 3 patients per 100 is:

Nervous System:Somnolence.

Less than 1 in 100 Patients. Adverse reactions estimated to occur at a rate of less than 1 in 100 patients listed below, grouped by organ system, and by decreasing order of occurrence are:

Nervous System: Agitation, confusion, hyperkinesia, ataxia, CNS depression, nightmares, nervousness, psychiatric disturbance, hallucinations, insomnia, anxiety, dizziness, thinking abnormality.

Respiratory System: Hypoventilation, apnea.

Cardiovascular System: Bradycardia, hypotension, syncope.

Digestive System: Nausea, vomiting, constipation.

Other Reported Reactions: Headache, hypersensitivity reactions (angioedema, skin rashes, exfoliative dermatitis), fever, liver damage, megaloblastic anemia following chronic phenobarbital use.

Drug Abuse And Dependence

Mephobarbital is a controlled substance in Narcotic Schedule IV. Barbiturates may be habit forming. Tolerance, psychological dependence, and physical dependence may occur especially following prolonged use of high doses of barbiturates. As tolerance to barbiturates develops, the amount needed to maintain the same level of intoxication increases; tolerance to a fatal dosage, however, does not increase more than two-fold. As this occurs, the margin between an intoxicating dosage and fatal dosage becomes smaller.

Symptoms of acute intoxication with barbiturates include unsteady gait, slurred speech, and sustained nystagmus. Mental signs of chronic intoxication include confusion, poor judgment, irritability, insomnia, and somatic complaints.

Symptoms of barbiturate dependence are similar to those of chronic alcoholism. If an individual appears to be intoxicated with alcohol to a degree that is radically disproportionate to the amount of alcohol in his or her blood the use of barbiturates should be suspected. The lethal dose of a barbiturate is far less if alcohol is also ingested.

The symptoms of barbiturate withdrawal can be severe and may cause death. Minor withdrawal symptoms may appear 8 to 12 hours after the last dose of a barbiturate. These symptoms usually appear in the following order: anxiety, muscle twitching, tremor of hands and fingers, progressive weakness, dizziness, distortion in visual perception, nausea, vomiting, insomnia, and orthostatic hypotension. Major withdrawal symptoms (convulsions and delirium) may occur within 16 hours and last up to 5 days after abrupt cessation of these drugs. Intensity of withdrawal symptoms gradually declines over a period of approximately 15 days. Individuals susceptible to a barbiturate abuse and dependence include alcoholics and opiate abusers, as well as other sedative-hypnotic and amphetamine abusers.

Drug dependence to barbiturates arises from repeated administration of a barbiturate or agent with barbiturate-like effect on a continuous basis, generally in amounts exceeding therapeutic dose levels. The characteristics of drug dependence to barbiturates include: (a) a strong desire or need to continue taking the drug; (b) a tendency to increase the dose; (c) a psychic dependence on the effects of the drug related to subjective and individual appreciation of those effects; and (d) a physical dependence on the effects of the drug requiring its presence for maintenance of homeostasis and resulting in a definite, characteristic, and self-limited abstinence syndrome when the drug is withdrawn.

Treatment of barbiturate dependence consists of cautious and gradual withdrawal of the drug. Barbiturate-dependent patients can be withdrawn by using a number of different withdrawal regimens. In all cases withdrawal takes an extended period of time. One method involves substituting a 30 mg dose of phenobarbital for each 100 mg to 200 mg dose of barbiturate that the patient has been taking. The total daily amount of phenobarbital is then administered in 3 to 4 divided doses, not to exceed 600 mg daily. Should signs of withdrawal occur on the first day of treatment, a loading dose of 100 mg to 200 mg of phenobarbital may be administered IM in addition to the oral dose. After stabilization on phenobarbital, the total daily dose is decreased by 30 mg a day as long as withdrawal is proceeding smoothly. A modification of this regimen involves initiating treatment at the patient's regular dosage level and decreasing the daily dosage by 10% if tolerated by the patient.

Infants physically dependent on barbiturates may be given phenobarbital 3 mg/kg/day to 10 mg/kg/day. After withdrawal symptoms (hyperactivity, disturbed sleep, tremors, hyperreflexia) are relieved, the dosage of phenobarbital should be gradually decreased and completely withdrawn over a 2-week period.

Read the entire FDA prescribing information for Mebaral (Mephobarbital)


What Is Epilepsy? Symptoms, Causes, and Treatments See Slideshow

© Mebaral Patient Information is supplied by Cerner Multum, Inc. and Mebaral Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.

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