SIDE EFFECTS: Dizziness, lightheadedness, drowsiness, difficulty urinating, trouble sleeping, headache, anxiety, and pain at the injection site may occur. If these effects persist or worsen, notify your doctor or pharmacist promptly. Dizziness and lightheadedness can increase the risk of falling. Get up slowly when rising from a sitting or lying position. Tell your doctor promptly if any of these side effects occur: muscle spasm/stiffness, shaking (tremor), restlessness, mask-like facial expression, drooling. Your doctor may prescribe another medication for you to take with haloperidol to decrease these side effects. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. In rare cases, haloperidol may increase your level of a certain chemical made by the body (prolactin). For females, this increase in prolactin may result in unwanted breast milk, missed/stopped periods, or difficulty becoming pregnant. For males, it may result in decreased sexual ability, inability to produce sperm, or enlarged breasts. If you develop any of these symptoms, tell your doctor right away. For males, in the unlikely event you have a painful or prolonged erection (lasting more than 4 hours), stop using this drug and seek immediate medical attention, or permanent problems may occur. This medication may rarely cause a condition known as tardive dyskinesia. In some cases, this condition may be permanent. Tell your doctor right away if you develop any facial/muscle twitching such as tongue thrusting, chewing movements, puffing or puckering of your mouth, or uncontrollable shaking. This medication may rarely cause a very serious condition called neuroleptic malignant syndrome (NMS). Get medical help right away if you have any of the following symptoms: fever, muscle stiffness/pain/tenderness/weakness, severe tiredness, severe confusion, sweating, fast/irregular heartbeat, dark urine, signs of kidney problems (such as change in the amount of urine). Tell your doctor right away if any of these rare but very serious side effects occur: persistent nausea/vomiting, stomach/abdominal pain, yellowing of eyes/skin, seizures, signs of infection (such as fever, persistent sore throat). Seek immediate medical attention if any of these rare but very serious side effects occur: slow heartbeat, severe dizziness, chest pain, fainting. A very severe allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of an allergic reaction include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before using haloperidol, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients (such as sesame oil), which can cause allergic reactions or other problems. Talk to your pharmacist for more details. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: a certain severe nervous system problem (severe CNS depression), Parkinson's disease. Before using this medication, tell your doctor or pharmacist your medical history, especially of: bipolar disorder, difficulty urinating (e.g., due to prostate problems), glaucoma, heart problems (e.g., angina), overactive thyroid (hyperthyroidism), seizures, low white blood cell count. Haloperidol decanoate may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away. The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using haloperidol decanoate, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death). Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using haloperidol decanoate safely. This drug may make you dizzy or drowsy. Alcohol or marijuana can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Limit alcoholic beverages. Talk to your doctor if you are using marijuana. Before having surgery, be sure to tell your doctor or dentist that you are using haloperidol. This medication can reduce sweating, making you more likely to get heatstroke. Avoid hard work and exercise in hot weather. Older adults may be more sensitive to the side effects of this drug, especially drowsiness, dizziness, lightheadedness, difficulty urinating, and heart effects such as QT prolongation (see above). Drowsiness, dizziness, and lightheadedness can increase the risk of falling. During pregnancy, this medication should be used only when clearly needed. Babies born to mothers who have used this drug during the last 3 months of pregnancy may rarely develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away. Since untreated mental/mood problems (such as schizophrenia) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy. This drug passes into breast milk and could have undesirable effects on a nursing infant. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Drug interactions may change how your medications work or increase your risk for serious side effects. This document does not contain all possible drug interactions. Keep a list of all the products you use (including prescription/nonprescription drugs and herbal products) and share it with your doctor and pharmacist. Do not start, stop, or change the dosage of any medicines without your doctor's approval. Some products that may interact with this drug include: anticholinergic medications (e.g., antispasmodics such as belladonna alkaloids, scopolamine), "blood thinners" (e.g., anticoagulants such as warfarin and heparin), cabergoline, ketoconazole, lithium, methyldopa, drugs for Parkinson's disease (e.g., levodopa and carbidopa, selegiline), paroxetine, pergolide, quinupristin-dalfopristin, rifampin, saquinavir. Many drugs besides haloperidol decanoate may affect the heart rhythm (QT prolongation), including amiodarone, dofetilide, pimozide, quinidine, sotalol, procainamide, and macrolide antibiotics (such as erythromycin), among others. Therefore, before using haloperidol, report all medications you are currently using to your doctor or pharmacist. Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana, drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or antihistamines (such as cetirizine, diphenhydramine). Check the labels on all your medicines (such as allergy or cough-and-cold products) because they may contain ingredients that cause drowsiness. Ask your pharmacist about using those products safely.

OVERDOSE: If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.