About phenobarbital
Barbiturate anticonvulsant and sedative
Used for
- Treatment of certain seizure disorders
- Short-term management of severe insomnia in selected cases
Usual adult dose
Seizures: commonly 60–200 mg by mouth daily, adjusted to response and blood levels.
Usual dose in children
Seizures: commonly 3–6 mg/kg by mouth daily, adjusted by a clinician.
Common side effects
- Drowsiness, dizziness, and impaired coordination
- Confusion or slowed thinking
- Nausea
- Dependence with prolonged use
Important warnings
- Can cause serious breathing suppression, especially with alcohol or other sedatives.
- Do not stop suddenly; withdrawal can cause seizures.
- May impair driving and alertness.
- Long-term use can weaken bones and increase fracture risk.
Pregnancy
May harm the fetus; use during pregnancy can also cause newborn withdrawal. Seizure treatment requires specialist oversight.
Breastfeeding
Passes into breast milk and may cause infant sleepiness or poor feeding; monitor for these effects.
Interactions
- Alcohol, opioids, and sedatives increase drowsiness and breathing risk.
- Can reduce the effectiveness of hormonal contraceptives and many other medicines.
- Valproate can increase phenobarbital effects.
- May lower levels of medicines including warfarin and some seizure drugs.
AI-generated from general medical knowledge, not from this product's official leaflet. It may be incomplete or out of date. Not medical advice — ask a pharmacist or doctor before making any decision.