+ -Text Size



Trade/other name(s): Compazine

Why would this drug be used?

Prochlorperazine is an anti-nausea medicine. It is also used for other purposes.

How does this drug work?

Prochlorperazine is part of a general class of drugs called phenothiazines. It helps prevent nausea and vomiting resulting from chemotherapy. It blocks messages to the part of the brain responsible for nausea and vomiting.

Before taking this medicine

Tell your doctor…

  • If you are allergic to anything, including medicines, dyes, additives, or foods.
  • If you have ever had seizures, have an abnormal EEG (brain wave study) or are taking anti-seizure medicines. This drug may raise your risk of seizures.
  • If you have an enlarged prostate or glaucoma. This drug can worsen the symptoms.
  • If you will be exposed to extreme heat while taking prochlorperazine. It can raise the risk of low blood pressure and other side effects.
  • If you have an abnormal heart rhythm, heart block, heart failure, or any heart problem. Prochlorperazine can lower the blood pressure and cause falling or fainting.
  • If you take tranquilizers (sedatives) such as diazepam (Valium), muscle relaxers, opioid pain medicines, or sleeping pills, or if you drink alcohol. Prochlorperazine may worsen the sleepiness caused by these substances.
  • If you have any medical conditions such as kidney disease, liver disease (including hepatitis), or diabetes. These conditions may require that your medicine dose, regimen, or timing be changed.
  • If you have asthma or emphysema (breathing problems). Prochlorperazine can worsen symptoms of these conditions.
  • If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of harm to the fetus if a woman takes this drug during pregnancy.
  • If you are breast-feeding. This drug passes into breast milk and could affect the baby.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs.

Interactions with other drugs

If taken with prochlorperazine, propranolol (Inderal) can raise the blood levels of both drugs in the body. This can increase the risk of dangerous side effects.

Prochlorperazine can slow down the excretion of phenytoin (Dilantin), which can raise the blood levels of phenytoin too high.

Medicines that make you urinate more (diuretics or "water pills") may cause your blood pressure to drop dangerously low if taken with prochlorperazine.

If lithium is taken with this drug, it may cause weakness, fever, tremor, confusion, involuntary movements. If this syndrome is not treated quickly, brain damage can result.

Epinephrine may lower the blood pressure (rather than raise it) if it is taken with prochlorperazine. Your doctor can substitute another drug if epinephrine's effects are needed.

Anticoagulants (blood thinners) may not work properly. You may need more monitoring or dose adjustments while you are on prochlorperazine.

Prochlorperazine may make you drowsy. This can add to the effects of other medicines or substances that make you sleepy or less alert, such as:

  • antihistamines
  • tranquilizers (sedatives)
  • sleeping pills
  • muscle relaxers
  • barbiturates
  • anti-seizure medicines
  • opioid pain medicines
  • anesthetics
  • antidepressants such as amitriptyline, desipramine, doxepin, imipramine, nortriptyline
  • anti-psychotic drugs
  • certain anti-nausea medicines
  • alcohol

They may cause harm if taken with prochlorperazine. Talk with your doctor or pharmacist if you are taking any of these.

Check with your doctor, nurse, or pharmacist about whether any of the medicines, vitamins, herbs, and supplements you are taking can cause problems with prochlorperazine.

Interactions with foods

No serious interactions with food are known at this time. Check with your doctor, nurse, or pharmacist about whether foods may be a problem.

Tell all the doctors, dentists, nurses, and pharmacists you visit that you are taking this drug.

How is this drug taken or given?

Prochlorperazine is given by mouth as a pill, long-acting capsule, liquid, rectal suppository, as an injection into the muscle, or an injection in a vein over 5 to 15 minutes.

The dose depends on the reason you are taking it and how well it has worked at the lowest dose. Take this drug exactly as directed by your doctor. If you do not understand the instructions, ask your doctor or nurse to explain them to you.

If you are taking antacids, take the prochlorperazine pill or capsule at least 2 hours before or after the antacid.

If you are taking the suppository, open the package and dip the tip of the suppository in cold water. If you are right-handed, lie down on your left side, bring your knees up near your chest, and insert the suppository in your rectum about an inch. Stay in this position for about 15 minutes, then get up and wash your hands well.

Keep the medicine in a tightly closed container away from heat and moisture and out of the reach of children and pets.


Prochlorperazine may make you feel very sleepy. Do not drive or operate heavy machinery when you are drowsy. Be careful getting up, changing position, or walking. Start slowly and hold onto something or someone to hold you steady. Have another responsible adult with you until you know how the medicine will affect you and that you can take care of yourself.

This drug may cause a quick drop in blood pressure when you go from lying down to sitting up, or from sitting to standing up (postural hypotension). This may cause you to feel dizzy or faint if you sit up or stand up too quickly, which can cause falls or injuries. Changing position slowly can reduce the risk of these problems. Let your doctor know if this happens to you.

Prochlorperazine may cause unplanned movements called extrapyramidal effects. These include restlessness, tremors, sticking out the tongue, muscle tightness, and unplanned muscle movements. Let your doctor or nurse know right away if this happens. These side effects usually go away when you stop taking the drug. The movements can also usually be stopped by other medicines such as diphenhydramine (Benadryl). Your doctor may need to stop the prochlorperazine.

Call your doctor or nurse right away if you have restlessness, muscle stiffness, severe anxiety, slow jerky movements, tiredness, weakness, fever, confusion, trouble walking, or yellow eyes or skin.

If you are scheduled for myelography studies (special x-rays of the space around the spinal cord), be sure your radiologist knows you are taking prochlorperazine. You will likely need to stop taking it 48 hours before the study and hold off starting back on it for at least 24 hours afterward.

At higher doses over long periods, prochlorperazine can cause a movement problem called tardive dyskinesia. If you notice repeated instances of puffing out of cheeks, puckering of the mouth, grimacing, chewing movements, or sticking out the tongue, contact the doctor or nurse right away. Stopping the drug quickly may allow these problems to go away.

Prochlorperazine may raise your risk of seizures if you have had them before.

This drug can cause a rare problem called neuroleptic malignant syndrome, with symptoms like fever, tight muscles, tremors, sweating, constipation, and confusion. This syndrome can become life-threatening if not treated right away. If you have symptoms like these, call your doctor without delay.

Possible side effects

You will probably not have most of the following side effects, but if you have any talk to your doctor or nurse. They can help you understand the side effects and cope with them.


  • dry mouth
  • constipation
  • sedation
  • sleepiness

Less common

  • blurred vision
  • restlessness, trouble sleeping
  • involuntary muscle movements or spasms (extrapyramidal effects)*
  • tremors*
  • increased appetite
  • weight gain
  • low blood pressure on sitting or standing, which can make you dizzy or faint*
  • increased heart rate
  • changes in electrical activity of heart (EKG changes), which can be serious


  • damage to liver (yellowing of the skin and the whites of the eyes)
  • rash
  • severe allergic reaction with itching, hives (skin welts), dizziness, trouble breathing or swallowing, swelling of the mouth, tongue, or face
  • increased sensitivity to sunlight with higher risk of sunburn
  • tardive dyskinesia (involuntary movements that may become permanent)*
  • low white blood count with increased risk of infection
  • neck spasms (cramps) and tightness in the throat, trouble swallowing
  • high body temperature*

*See the "Precautions" section for more detailed information.

There are other side effects not listed above that can also occur in some patients. Tell your doctor or nurse if you develop these or any other problems.

FDA approval

Yes – first approved before 1984 (FDA cannot verify dates of drugs approved before 1984.)

Disclaimer: This information does not cover all possible uses, actions, precautions, side effects, or interactions. It is not intended as medical advice, and should not be relied upon as a substitute for talking with your doctor, who is familiar with your medical needs.

Last Medical Review: 10/13/2009
Last Revised: 10/13/2009