Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For haloperidol, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to haloperidol. Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Haloperidol has not been studied in pregnant women. However, studies in animals given 2 to 20 times the usual maximum human dose of haloperidol have shown reduced fertility, delayed delivery, cleft palate, and an increase in the number of stillbirths and newborn deaths.

Breast-feeding—Haloperidol passes into breast milk. Animal studies have shown that haloperidol in breast milk causes drowsiness and unusual muscle movements in the nursing offspring. Breast-feeding is not recommended during treatment with haloperidol.

Children—Side effects, especially muscle spasms of the neck and back, twisting movements of the body, trembling of fingers and hands, and inability to move the eyes are more likely to occur in children, who usually are more sensitive than adults to the effects of haloperidol.

Older adults—Constipation, dizziness or fainting, drowsiness, dryness of mouth, trembling of the hands and fingers, and symptoms of tardive dyskinesia (such as rapid, worm-like movements of the tongue or any other uncontrolled movements of the mouth, tongue, or jaw, and/or arms and legs) are especially likely to occur in elderly patients, who are usually more sensitive than younger adults to the effects of haloperidol.

Other medicines—Although certain medicines should not be used together at all, in other cases 2 different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking haloperidol, it is especially important that your health care professional know if you are taking any of the following:

• Amoxapine (e.g., Asendin) or
• Metoclopramide (e.g., Reglan) or
• Metyrosine (e.g., Demser) or
• Other antipsychotics (medicine for mental illness) or
• Pemoline (e.g., Cylert) or
• Pimozide (e.g., Orap) or
• Promethazine (e.g., Phenergan) or
• Rauwolfia alkaloids (alseroxylon [e.g., Rauwiloid], deserpidine [e.g., Harmonyl], rauwolfia serpentina [e.g., Raudixin], reserpine [e.g., Serpasil]) or
• Trimeprazine (e.g., Temaril)—Taking these medicines with haloperidol may increase the frequency and severity of certain side effects

• Central nervous system (CNS) depressants (medicine that causes drowsiness) or
• Tricyclic antidepressants (medicine for depression)—Taking these medicines with haloperidol may result in increased CNS and other depressant effects, and in an increased chance of low blood pressure (hypotension)

• Epinephrine (e.g., Adrenalin)—Severe low blood pressure or irregular heartbeat may occur

• Levodopa (e.g., Dopar, Larodopa)—Haloperidol may interfere with the effects of this medicine

• Lithium (e.g., Eskalith, Lithane)—Although lithium and haloperidol are sometimes used together, their use must be closely monitored by your doctor, who may change the amount of medicine you need to take

Other medical problems—The presence of other medical problems may affect the use of haloperidol. Make sure you tell your doctor if you have any other medical problems, especially:

• Alcohol abuse—The risk of heat stroke may be increased

• Difficult urination or
• Glaucoma or
• Heart or blood vessel disease or
• Lung disease or
• Parkinson's disease—Haloperidol may make the condition worse

• Epilepsy—The risk of seizures may be increased

• Kidney disease or
• Liver disease—Higher blood levels of haloperidol may occur, increasing the chance of side effects

• Overactive thyroid—Serious unwanted effects may occur