• 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.

Rifampin may lower the level of haloperidol in the body so that the haloperidol does not work.

If lithium is taken with this drug, it has rarely been reported to cause weakness, fever, tremor, confusion, and 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 given with haloperidol. The doctor can substitute another drug if epinephrine's effects are needed.

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.

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

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.

At higher doses over long periods, haloperidol 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.

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.

• feeling calm (sedated)
• sleepiness

• slow breathing rate
• 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
• 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.