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How does this medicine work?

Phenobarbital (fee-no-bar-bih-tahl) is most often used to help control seizures.

How should I give it?

This medicine comes in liquid, pill, and injectable (shot) forms. Give it at regular times to keep a steady level in the bloodstream. Your child should be awake and alert when taking any medicine. Follow the checked instructions below:

___ If giving a liquid medicine, draw up the correct amount in the medicine dropper or oral syringe. Give a small squirt of the medicine inside the cheek. To avoid choking, let your child swallow each squirt before giving more.

___ For babies, you may want to mix the medicine with a small amount of formula or breast milk and give it with a bottle nipple before a feeding. Do not add medicine to a whole bottle because if your baby does not finish it, you will not know how much of the medicine was taken.
___ If the prescription is a pill and your child cannot swallow pills, crush it between 2 spoons or inside a plastic bag or folded paper. Mix with a very small amount (about 1 teaspoon) of soft food such as applesauce, yogurt, ice cream, jelly, or chocolate syrup.

Other instructions:




Are there any precautions about food or other medicines?

Phenobarbital can be given with or without food. Avoid any alcohol-containing foods or medicines such as cough syrup.

Some prescribed medicines interact with phenobarbital. Always tell your doctor or pharmacist that your child is taking it.

Long use of phenobarbital can decrease the levels of vitamins D, K, and folic acid in the body. Include good sources of these vitamins in your child's diet. (If your child is on chemotherapy, check with the oncologist because folic acid may affect the growth of cancer cells.)

Foods high in vitamin D:

  • margarine
  • eggs
  • milk and dairy products
  • infant formula
  • fortified breakfast cereals
  • sardines, salmon

Foods high in vitamin K:

  • eggs
  • green leafy vegetables (such as broccoli, spinach)
  • infant formula
  • meats
  • small amounts in fortified cereals

Foods high in folic acid:

  • dried beans and legumes
  • green leafy vegetables
  • avocados
  • infant formula
  • liver
  • yeast breads
  • whole-wheat breads and other products
  • wheat germ

For information on other foods that contain these vitamins, or if you have questions, ask the doctor or nutritionist.

What should I do if a dose is missed?

If a dose is missed, give it as soon as you remember, unless it is less than 4 hours before the next dose. In that case, skip the missed dose and continue with the regular schedule. Never give a double dose. If more than 2 doses are missed in a 24-hour period, call your doctor.

If your child vomits (throws up) within 15 minutes after a dose, give it again. If your child vomits after 15 minutes, do not repeat the dose.

Call the doctor if your child misses or vomits 2 doses in a row.

What are the side effects?

  • drowsiness
  • irritability
  • unsteadiness
  • nausea (upset stomach)
  • vomiting (throwing up)
  • constipation
  • nervousness

When should I call the doctor?

  • continued vomiting
  • hives or severe skin rash
  • swelling of eyelids or face
  • yellowing of eyes or skin
  • child cannot be wakened easily
  • slurred speech
  • uncontrolled eye movements
  • confusion
  • trouble breathing - call 911

What else do I need to know?

Give the phenobarbital until the doctor says to stop.

The doctor may want your child to have a blood test to be sure there is the right amount of medicine in the blood.

You and your child should know the names of all the medicines he or she is taking. Share this information with anyone involved in your child's care. Please bring the medicine container when your child comes to the clinic or emergency department.

Always make sure you have enough medicine on hand. Each time you refill your prescriptions, check to see how many refills are left. If no refills are left, the pharmacist will need 2 or 3 days to contact the clinic to renew the prescription.

Check the label and expiration date before giving each dose. Ask your pharmacist what to do with outdated or unused medicines. If there is no "take-back" program empty them into the trash.

Store all medicines in their original container and away from direct sunlight or heat. Do not store in humid places such as the bathroom. Keep them out of children's reach, locked up if possible.

If too much or the wrong kind of medicine is taken, call the Poison Control Center at 1-800-222-1222. If your child is unconscious, call 911.


This sheet is not specific to your child, but provides general information. If you have any questions, please call the doctor or pharmacist.

Children's Hospitals and Clinics of Minnesota
Patient/Family Education
2525 Chicago Avenue South
Minneapolis, MN 55404
Last reviewed 8/2015 ©Copyright

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This page is not specific to your child, but provides general information on the topic above. If you have any questions, please call your clinic. For more reading material about this and other health topics, please call or visit Children's Minnesota Family Resource Center library, or visit

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