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Pentobarbital (By injection)

Pentobarbital (pen-toe-BAR-bi-tal)

Relieve tension, anxiety, nervousness, and insomnia (trouble sleeping). Also helps you relax before having surgery or a medical procedure. Also treats epilepsy and other seizures. This medicine is a barbiturate.

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

You should not use this medicine if you have had an allergic reaction to pentobarbital, or to other barbiturates. You should not use this medicine if you are pregnant, or if you have porphyria (blood disease).

How to Use This Medicine:


  • Your doctor will prescribe your exact dose, and how often it should be given. This medicine is given through a needle placed in one of your veins or as a shot into a muscle.
  • A nurse or other health provider will give you this medicine.

Drugs and Foods to Avoid:

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

  • Make sure your doctor knows if you are also using steroid medicine (such as dexamethasone, prednisolone, prednisone, or Medrol®), or medicine for seizures such as phenytoin (Dilantin®), valproate sodium (Depacon®), or valproic acid (Depakene®).
  • Make sure your doctor knows if you are also using an MAO inhibitor such as Eldepryl®, Marplan®, Nardil®, or Parnate®, or a blood thinner such as warfarin (Coumadin®). Tell your doctor if you are using a medicine to treat an infection such as doxycycline (Vibramycin®) or griseofulvin (Grifulvin V®).
  • Birth control pills may not work as well while you are using phenobarbital. To keep from getting pregnant, use another form of birth control such as condoms, a diaphragm, or contraceptive foam or jelly.
  • There are many other drugs that interact with this medicine. Make sure your doctor knows all other medicines you are using.
  • Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.
  • Do not drink alcohol while you are using this medicine.

Warnings While Using This Medicine:

  • It is not safe to take this medicine during pregnancy. It could harm an unborn baby. Tell your doctor right away if you become pregnant.
  • Make sure your doctor knows if you are breast feeding, have untreated depression, liver disease, or if you have a history of drug abuse.
  • This medicine can be habit-forming. Do not use more than your prescribed dose. Call your doctor if you think your medicine is not working.
  • Do not stop using this medicine suddenly. Your doctor will need to slowly decrease your dose before you stop it completely.
  • This medicine may make you dizzy or drowsy. Avoid driving, using machines, or doing anything else that could be dangerous if you are not alert.

Possible Side Effects While Using This Medicine:

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

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Dark-colored urine or pale stools.
  • Fast or slow heartbeat.
  • Fever, chills, chest pain, or trouble breathing.
  • Lightheadedness or fainting.
  • Pain, swelling, itching, or a lump under your skin where the needle is placed.
  • Severe confusion, drowsiness, or muscle weakness.
  • Severe nausea, vomiting, or pain in your upper stomach.
  • Yellowing of your skin or the whites of your eyes.

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

  • Anxiety, nervousness, irritability, or headache.
  • Dizziness or confusion.
  • Mild nausea, vomiting, loss of appetite, diarrhea, or constipation.
  • Problems with your vision.
  • Trouble sleeping.

If you notice other side effects that you think are caused by this medicine, tell your doctor

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

Last Updated: 5/1/2020

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