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Trade/other name(s): Haldol

Why would this drug be used?

Haloperidol is an antipsychotic drug, and is mainly used to treat mental health problems such as agitation and psychosis. It is also used to treat nausea and vomiting resulting from chemotherapy.

How does this drug work?

Haloperidol is a member of a general class of drugs called butyrophenones. These drugs can block messages to the part of the brain responsible for nausea and vomiting, making them useful in treating the nausea and vomiting that can occur after chemotherapy. The exact way it does this is unknown.

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 waves) or are taking anti-seizure medicines. This drug may raise your risk of seizures.
  • If you have prostate enlargement or glaucoma. This drug can worsen your symptoms.
  • If you have thyroid problems. Haloperidol can cause nervous system problems including rigid muscles and inability to walk and talk.
  • If you have an abnormal heart rhythm, heart block, heart failure, or any problem with the heart's electrical system, including long Q-T syndrome. Haloperidol can slow down the heart's electrical impulses and make these problems worse. It can also lower the blood pressure and deprive the heart of oxygen.
  • If you have low potassium or low magnesium, or if you are taking medicines such as diuretics ("water pills") that may cause your potassium or magnesium levels to drop. Haloperidol can slow down the heart's electrical impulses and these problems may make it more dangerous.
  • If you have taken chemotherapy drugs that can damage the heart, such as daunorubicin, doxorubicin, epirubicin, or idarubicin. These medicines may worsen the effects on the heart.
  • If you take tranquilizers (sedatives) such as diazepam (Valium) or drink a lot of alcohol. This may increase the chance of the heart rhythm problem mentioned above.
  • If you have liver or kidney disease. Haloperidol can pose a higher risk of side effects if these are present.
  • 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 may harm the baby.
  • About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs. In fact, keeping a written list of each of these medicines (including the doses of each and when you take them) with you in case of emergency may help prevent complications if you get sick.

Interactions with other drugs

Any drug that affects the heart’s rhythm or causes the electrical impulses of the heart to change can worsen the effect of haloperidol on the heart. This includes some cancer drugs, many drugs used to treat nausea after chemotherapy, and some antibiotics.

  • Medicines that are used to help irregular heartbeat may worsen the effect of haloperidol on the heart's electrical system.
  • Many drugs that are used for mental health conditions (certain antidepressants, antipsychotics, and sedatives) can cause electrical problems in the heart that may be worsened by haloperidol. Some of these same drugs can also raise the levels of haloperidol in the blood, which can add to this risk.
  • Medicines that make you urinate more (diuretics or "water pills") may worsen electrical problems with the heart by lowering your potassium and magnesium levels.

Rifampin (and related drugs for tuberculosis) may lower the level of haloperidol in the body so that the haloperidol does not work. Carbamazepine (Tegretol®) may have the same effect.

If lithium is taken with this drug, it has been reported to cause weakness, fever, tremor, confusion, and involuntary movements. If this rare syndrome is not treated quickly, permanent brain damage can result.

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

Paroxetine (Paxil) can raise the haloperidol level in the body and worsen side effects, including those on the heart.

Certain antifungal drugs such as ketoconazole and itraconazole may raise the level of haloperidol in the body and worsen its side effects.

Medicines for Parkinson's disease may increase the pressure inside the eyeball if taken with haloperidol.

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

This drug may cause a sudden drop in blood pressure when sitting or standing up quickly. It should be used with caution in people who are taking blood pressure medicine.

Haloperidol 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

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

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?

Haloperidol is given two ways: as an injection in a muscle, or by mouth as a pill or liquid concentrate. It is sometimes given in the vein, although IV use has not been approved by the FDA; and the risk of certain serious side effects are higher.

The dose is determined by your weight and how well the drug works for you. 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.

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


Haloperidol can make you feel very sleepy. Do not drive or operate heavy machinery if this medicine makes you feel drowsy.

Haloperidol may cause unplanned movements called extrapyramidal effects. These include restlessness, tremors, sticking out the tongue, 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 also need to stop the haloperidol.

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.

Call your doctor or nurse if you have restlessness, muscle stiffness, severe anxiety, slow jerky movements, tiredness, weakness, fast or irregular heartbeat, or yellow eyes or skin.

In rare cases, haloperidol can cause changes in the heart's rhythm, some of which can be dangerous. Get emergency help if you have irregular heart beat, blue nail beds or skin, gasping for breath, or seizure.

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.

This drug can turn your urine pink or reddish brown, and is not a harmful effect. It goes away when you stop the drug.

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.


  • feeling calm (sedated)
  • sleepiness

Less common

  • slow breathing
  • faster heart rate*
  • drop in blood pressure on sitting or standing which can make you dizzy or faint*
  • high or low blood pressure*
  • restlessness, agitation


  • dry mouth
  • trouble passing urine
  • blurred vision or change in vision (poor night vision, or seeing everything with a brown tint)
  • constipation
  • neck spasms (cramps) and tightness in the throat, trouble swallowing
  • unplanned (involuntary) movements, which may not go away*
  • change in electrical impulses in the heart, which can be serious*
  • increased sensitivity to sun, easier to burn
  • high body temperature, heat stroke
  • permanent damage to the brain, mainly when used with lithium
  • damage to liver, with yellow eyes or skin*
  • sudden death due to abnormal heart rhythm or other causes*

*See "Precautions" section for more detailed information.

There are some 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: 10/12/2009
Last Revised: 10/12/2009