About phenobarbital
Barbiturate anticonvulsant
Used for
- Treatment of epilepsy and prevention of seizures.
- Sometimes used for sedation or withdrawal treatment in specialist care.
Usual adult dose
For epilepsy, commonly 60–180 mg once daily; dose is adjusted to response and blood levels.
Usual dose in children
For epilepsy, commonly 3–6 mg/kg once daily; specialist-directed dosing varies with age and blood levels.
Common side effects
- Drowsiness, dizziness, and poor coordination.
- Unsteadiness or slowed thinking.
- Mood changes or agitation.
- Long-term use may weaken bones.
Important warnings
- Can cause dependence; do not stop suddenly, as seizures may worsen.
- May impair alertness and breathing, especially with alcohol or sedatives.
- Seek urgent care for severe rash, facial swelling, or breathing difficulty.
- Use cautiously with liver or breathing problems, and in older adults.
Pregnancy
Can harm an unborn baby and may affect vitamin K; specialist review is important before or during pregnancy.
Breastfeeding
Passes into breast milk and may cause infant sleepiness or poor feeding; monitor the baby with clinical guidance.
Interactions
- Reduces effectiveness of hormonal contraceptives and many other medicines.
- Alcohol, opioids, and sedatives can increase sleepiness and breathing problems.
- Other medicines may alter phenobarbital levels; examples include valproate.
- Can reduce levels of anticoagulants and some seizure medicines.
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 It may be incomplete or out of date.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.