Phenobarbital: Side Effects, Uses & Monitoring
Sedative.
- Data source
- FDA labeling via NIH DailyMed (label 7741e9ab…)
- Label version
- current
- Last reviewed
- 2026
Reported adverse reactions
Reactions listed in current FDA labeling, with the highest frequency reported across summarized placebo-controlled trials.
No structured frequency data available in current labeling. Consult the official label.
Labeled uses (from FDA prescribing information)
Sedative. Sedation is obtainable within an hour, and in adequate dosage, the duration of action is more than six hours. Included in the more common conditions in which the sedative action of this class of drugs is desired are anxiety-tension states, hyperthyroidism, essential hypertension, nausea and vomiting of functional origin, motion sickness, acute labyrinthitis, pylorospasm in infants, chorea and cardiac failure. Phenobarbital is also a useful adjunct in treatment of hemorrhage from the respiratory or gastrointestinal tract. Phenobarbital controls anxiety, decreases muscular activity and lessens nervous excitability in hyperthyroid patients. However, thyrotoxic individuals occasionally react poorly to barbiturates. Hypnotic, for the short-term treatment of insomnia, since it appears to lose its effectiveness for sleep induction and sleep maintenance after 2 weeks (see CLINICAL PHARMACOLOGY ). Preanesthetic. Long-term anticonvulsant, (phenobarbital, mephobarbital and metharbital) for the treatment of generalized tonic-clonic and cortical focal seizures. And, in the emergency control of certain acute convulsive episodes, e.g., those associated with status epilepticus, cholera, …
Conditions associated with Phenobarbital in labeling
Anxiety Disorder
A group of mental health conditions characterized by excessive worry, fear, or nervousness that interferes wit...
Cholera
Cholera is a medical condition that may be associated with various symptoms and signs....
Generalized Anxiety Disorder
Persistent, excessive worry about everyday situations that is difficult to control and interferes with daily l...
Hypertension
Chronically elevated blood pressure that puts strain on the heart, blood vessels, kidneys, and brain. Often ha...
Hyperthyroidism
A condition in which the thyroid gland produces too much thyroid hormone, speeding up metabolism and causing w...
Insomnia
Difficulty falling asleep, staying asleep, or getting restful sleep despite adequate opportunity, affecting da...
Frequently Asked Questions
What is Phenobarbital used for?
FDA labeling lists the approved uses shown above under "Labeled uses." This summary is informational; only a qualified prescriber can determine whether a medication is appropriate for you.
What are the most commonly reported side effects of Phenobarbital?
Current labeling for this ingredient does not include a structured frequency table that we can reproduce. Review the official label linked below.
Does Phenobarbital require lab monitoring?
Monitoring needs vary. Ask your healthcare provider whether any lab tests apply while taking Phenobarbital.
Where does this information come from?
All clinical facts on this page were extracted from the current FDA-registered product labeling for this ingredient, published by manufacturers through NIH DailyMed. See the source link below.
Medical disclaimer: Educational content extracted from public FDA labeling. Not medical advice. Always consult a qualified healthcare professional before starting, stopping, or changing any medication.