Phenobarbital (By mouth)

There may be other brand names for this medicine.

Tablet, Capsule, Liquid

• Your doctor will tell you how much to take and how often.
• It is best to take this medicine on an empty stomach.

If a dose is missed:

• Take the missed dose as soon as possible.
• Skip the missed dose if it is almost time for your next dose.
• You should not use two doses at the same time.

• Store at room temperature, away from heat, direct light, and moisture.
• Ask your pharmacist, doctor, or health caregiver about the best way to dispose of any outdated medicine or medicine no longer needed.
• Keep all medicine away from children.

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

• Avoid drinking alcohol.
• Avoid taking other medicines that make you sleepy, such as sleeping pills, sedatives, or cold or allergy medicines while taking phenobarbital.
• Before taking this medicine, make sure your doctor knows if you are taking blood thinners (Coumadin®), corticosteroids, phenytoin (Dilantin®), valproic acid (Depakane®), doxycycline, or griseofulvin.
• Birth control pills may not work if you take them while taking phenobarbital. Use another form of birth control while taking this medicine.

• Check with your doctor before taking if you are pregnant, breastfeeding, or are planning to become pregnant, or if you have any type of lung disease, asthma, or liver disease.
• If you are using this medicine regularly, do not stop taking it suddenly without first asking your doctor. You may need to take less and less before stopping completely.
• You should not use more of this medicine or take it for longer periods than your doctor has ordered. Phenobarbital can be habit-forming.
• This medicine can make you drowsy. Be careful when driving or operating machinery.

Call your doctor right away if you notice any of these side effects:

• Hives or severe skin rash
• Swelling of eyelids or face
• Severe drowsiness, confusion, or slurred speech
• Shortness of breath or trouble breathing
• Uncontrollable eye movements
• Yellowing of eyes or skin
• Hallucinations

If you notice these less serious side effects, talk with your doctor:

• Drowsiness, dizziness, unsteadiness, "hangover" effects, trouble concentrating
• Nausea, vomiting
• Depressed mood
• Constipation
• Irritability, nervousness or excitement

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088