SIDE EFFECTS: Drowsiness, constipation, dry mouth, dizziness, lightheadedness, blurred vision, tiredness, or unexplained weight gain may occur. If any of 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. 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. Some people using this medication do not have serious side effects. This drug may cause muscle/nervous system problems (extrapyramidal symptoms-EPS). Your doctor may prescribe another medication to decrease these side effects. Therefore, tell your doctor right away if you notice any of the following side effects: increased anxiety, drooling/trouble swallowing, restlessness/constant need to move, shaking (tremor), shuffling walk, stiff muscles. Tell your doctor right away if any of these unlikely but serious side effects occur: difficulty urinating. This medication may cause a condition known as tardive dyskinesia. In some cases, this condition may be permanent. Tell your doctor right away if you develop any involuntary/repetitive muscle movements such as lip smacking/puckering, tongue thrusting, chewing, or finger/toe movements. In rare cases, perphenazine 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. Tell your doctor right away if any of these rare but very serious side effects occur: easy bruising/bleeding, slow heartbeat, signs of infection (e.g., sore throat), severe muscle spasm/cramping (e.g., twisting neck, arching back, eyes rolling up), persistent nausea, seizures, stomach/abdominal pain, yellowing eyes/skin. Get medical help right away if you have any very serious side effects, including: fast/irregular heartbeat, severe dizziness, fainting. 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). A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: 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 taking perphenazine, tell your doctor or pharmacist if you are allergic to it, or to other phenothiazines (e.g., chlorpromazine, fluphenazine), or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details. Before using this medication, tell your doctor or pharmacist your medical history, especially of: decreased bone marrow function, serious head injury, liver problems, nervous system problem (such as coma, drug/alcohol overdose, shock), Parkinson's disease, history of alcohol/substance abuse, low blood pressure, breathing problems (such as asthma, emphysema), breast cancer, fast/irregular heartbeat, heart valve problems, a certain adrenal gland tumor (pheochromocytoma), restless legs syndrome, seizure disorder, a certain severe reaction to other medications (neuroleptic malignant syndrome), difficulty urinating (e.g., due to prostate problems). Perphenazine 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 perphenazine, 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 perphenazine safely. This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana. This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness. Before having surgery, tell your doctor or dentist that you are taking this medication. Caution is advised during hot weather because perphenazine can reduce sweating, increasing your risk for a severe reaction to too much heat (heatstroke). Drink plenty of fluids. Avoid strenuous exercise in hot weather. If you become overheated, promptly seek cooler shelter and/or stop exercising. Seek immediate medical attention if your body temperature is above normal or if you have mental/mood changes, headache, or dizziness. Older adults may be more sensitive to the side effects of this drug, especially dizziness, lightheadedness, drowsiness, extrapyramidal symptoms, tardive dyskinesia, and 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, bipolar disorder, schizoaffective disorder) 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. Perphenazine passes into breast milk and may 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 are: certain drugs used for Parkinson's (e.g., bromocriptine, levodopa, pergolide), certain anticholinergic medications (e.g., dicyclomine, scopolamine), drugs affecting liver enzymes that remove perphenazine from your body (e.g., amiodarone, duloxetine, fluoxetine, paroxetine, ritonavir). 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. Symptoms of overdose may include: slow/shallow breathing, inability to wake up (coma).