Generic Name: Thioridazine (thye-oh-RID-a-zeen)Brand Name: Generic only. No brands available.

Thioridazine may increase your risk of severe irregular heartbeat or sudden death. Thioridazine should only be used in patients who have not shown improvement with or are unable to take other medicines.

Thioridazine is used for:

Treating schizophrenia in patients who have not shown improvement with or are unable to take other medicines. It may also be used for other conditions as determined by your doctor.

Thioridazine is a phenothiazine. It is not known exactly how it works.

Do NOT use Thioridazine if:

  • you are allergic to any ingredient in Thioridazine or similar medicines (eg, phenothiazines)
  • you have a decreased level of consciousness, severe high or low blood pressure, low levels of potassium in the blood, abnormal heart function test (ECG), or a history of certain heart problems (eg, irregular heartbeat, congenital long QT syndrome)
  • you have a genetic problem that leads to decreased levels of the P-450 2D6 isozyme in your body
  • you are taking antiarrhythmics (eg, amiodarone, quinidine), cisapride, dofetilide, H1 antagonists (eg, astemizole, terfenadine), pergolide, pindolol, propranolol, sparfloxacin, selective serotonin reuptake inhibitor (SSRI) antidepressants (eg, fluoxetine, paroxetine, fluvoxamine), streptogramins (eg, dalfopristin), or medicines that may affect your heartbeat. Ask your doctor or pharmacist if you are unsure if any of your medicines may affect your heartbeat

Contact your doctor or health care provider right away if any of these apply to you.

Before using Thioridazine :

Some medical conditions may interact with Thioridazine . Tell your doctor or pharmacist if you have any medical conditions, especially if any of the following apply to you:

  • if you are pregnant, planning to become pregnant, or are breast-feeding
  • if you are taking any prescription or nonprescription medicine, herbal preparation, or dietary supplement
  • if you have allergies to medicines, foods, or other substances
  • if you have a history of heart problems (eg, slow heartbeat), high or low blood pressure, blood problems (eg, porphyria), bone marrow problems (eg, low blood platelet levels, low white blood cell count), liver problems (eg, cirrhosis), kidney problems, enlarged prostate gland, seizures or epilepsy, Parkinson disease, Reye syndrome, or a history of breast cancer
  • if you have increased pressure in the eyes or glaucoma, or if you are at risk for glaucoma
  • if you are regularly exposed to extreme heat or phosphorus insecticides
  • if you have a history of alcohol abuse or if you drink more than 3 alcohol-containing drinks per day

Some MEDICINES MAY INTERACT with Thioridazine . Tell your health care provider if you are taking any other medicines, especially any of the following:

  • Anticholinergics (eg, atropine) because they may decrease the effectiveness of Thioridazine
  • Antiarrhythmics (eg, amiodarone, quinidine), arsenic, beta-blockers (eg, propranolol), cisapride, dofetilide, droperidol, H1 antagonists (eg, astemizole, terfenadine), haloperidol, ketolides (eg, telithromycin), macrolide antibiotics (eg, erythromycin), pimozide, pindolol, quinolones (eg, sparfloxacin, levofloxacin), serotonin norepinephrine reuptake inhibitors (eg, duloxetine), serotonin receptor antagonist antiemetics (eg, dolasetron), SSRI antidepressants (eg, fluoxetine, paroxetine, fluvoxamine), streptogramins (eg, dalfopristin), ziprasidone, or other medicines that may affect your heartbeat because risk of severe and possibly fatal side effects, including severe irregular heartbeat, may be increased. Ask your doctor or pharmacist if you are unsure if any of your medicines may affect your heartbeat.
  • Atropine, barbiturates (eg, phenobarbital), narcotics (eg, codeine), or tricyclic antidepressants (eg, amitriptyline) because risk of side effects may be increased by Thioridazine
  • Guanethidine, levodopa, or pergolide because their effectiveness may be decreased by Thioridazine

This may not be a complete list of all interactions that may occur. Ask your health care provider if Thioridazine may interact with other medicines that you take. Check with your health care provider before you start, stop, or change the dose of any medicine.

How to use Thioridazine :

Use Thioridazine as directed by your doctor. Check the label on the medicine for exact dosing instructions.

  • Thioridazine may be taken with or without food. If stomach upset occurs, take with food to reduce stomach irritation.
  • Continue to use Thioridazine even if you feel well. Do not miss any doses.
  • If you miss a dose of Thioridazine , take it as soon as possible. If it is almost time for your next dose, skip the missed dose and go back to your regular dosing schedule. Do not take 2 doses at once.

Ask your health care provider any questions you may have about how to use Thioridazine .

Important safety information:

  • Thioridazine may cause drowsiness, dizziness, or blurred vision. Do not drive, operate machinery, or do anything else that could be dangerous until you know how you react to Thioridazine . Using Thioridazine alone, with certain other medicines, or with alcohol may lessen your ability to drive or perform other potentially dangerous tasks.
  • Avoid drinking alcohol or taking other medications that cause drowsiness (eg, sedatives, tranquilizers) while taking Thioridazine . Thioridazine will add to the effects of alcohol and other depressants. Ask your pharmacist if you have questions about which medicines are depressants.
  • Alcohol, hot weather, exercise, and fever can increase the risk of dizziness, lightheadedness, or fainting. To prevent these effects, sit up or stand slowly, especially in the morning. Also, sit or lie down at the first sign of dizziness, lightheadedness, or weakness.
  • Do not become overheated in hot weather or during exercise or other activities because heatstroke may occur.
  • Involuntary and uncontrollable movements may develop with use of Thioridazine . Occurrence is highest among the elderly, especially women. The risk of developing these involuntary movements and the likelihood they will become permanent are increased with long-term use and with high doses. However, it is possible to develop these symptoms after short-term treatment at low doses. Contact your doctor at once if any of the following occur: involuntary movements of tongue, face, mouth, or jaw (eg, sticking out of the tongue, puffing of cheeks, puckering of mouth, chewing movements), or involuntary movements of the arms and legs.
  • Neuroleptic malignant syndrome (NMS) is a serious side effect associated with Thioridazine . Symptoms include increased body heat; muscle rigidness; altered mental abilities, including lack of response to your surroundings; irregular or fast heartbeat; or sweating. Contact your doctor at once if any of these symptoms occur.
  • Before you have any medical or dental treatments, emergency care, or surgery, tell the doctor or dentist that you are using Thioridazine .
  • Thioridazine may cause false results in some pregnancy tests. Check with your doctor if you have any questions or concerns. Make sure your doctor and laboratory personnel know you are using Thioridazine .
  • LAB TESTS, including heart function tests and blood potassium levels,, may be performed to monitor your progress or to check for side effects. Be sure to keep all doctor and lab appointments.
  • Use Thioridazine with caution in the ELDERLY because they may be more sensitive to its effects, especially dizziness, lightheadedness (especially upon standing), involuntary muscle movements, and blood problems (low white blood cell levels).
  • PREGNANCY and BREAST-FEEDING: If you become pregnant, discuss with your doctor the benefits and risks of using Thioridazine during pregnancy. Thioridazine is excreted in breast milk. Do not breast-feed while taking Thioridazine .

If you suddenly stop taking Thioridazine , especially if you have been taking high doses, you may experience WITHDRAWAL symptoms, including nausea, vomiting, dizziness, and tremors.

Possible side effects of Thioridazine :

All medicines may cause side effects, but many people have no, or minor, side effects. Check with your doctor if any of these most COMMON side effects persist or become bothersome:

Agitation; bizarre dreams; constipation; diarrhea; dizziness; drowsiness; dry mouth; loss of appetite; nausea; stuffy nose; vomiting.

Seek medical attention right away if any of these SEVERE side effects occur:

Severe allergic reactions (rash; hives; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); changes in menstrual period; changes in sexual ability; chest pain; confusion; dark urine; difficulty swallowing; drooling; fainting; fast, slow, or irregular heartbeat; fever, chills, or sore throat; hyperactivity; involuntary movements or spasms of the arms, legs, tongue, face, mouth, or jaw; mask-like face; muscle restlessness; restlessness; seizures; severe or persistent dizziness; severe constipation; shuffling walk; sleeplessness; sore mouth or gums; stiff or rigid muscles; stomach pain; sweating; swelling of the hands or feet; trouble urinating; unusual bruising or bleeding; unusual eye movements or inability to move eyes; unusual mood or mental changes, including lack of response to your surroundings; vision changes; weakness of arms or legs; yellowing of the skin or eyes.

This is not a complete list of all side effects that may occur. If you have questions about side effects, contact your health care provider. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects at

If OVERDOSE is suspected:

Contact 1-800-222-1222 (the American Association of Poison Control Centers), your local poison control center (, or emergency room immediately. Symptoms may include deep sleep or loss of consciousness; fast, slow, or irregular heartbeat; muscle spasms; restlessness; seizures; severe drowsiness; shortness of breath; tremors; trouble urinating; twitching.

Proper storage of Thioridazine :

Store Thioridazine at room temperature, between 59 and 86 degrees F (15 and 30 degrees C), in a tightly closed container. Store away from heat, moisture, and light. Do not store in the bathroom. Keep Thioridazine out of the reach of children and away from pets.

General information:

  • If you have any questions about Thioridazine , please talk with your doctor, pharmacist, or other health care provider.
  • Thioridazine is to be used only by the patient for whom it is prescribed. Do not share it with other people.
  • If your symptoms do not improve or if they become worse, check with your doctor.
  • If using Thioridazine for an extended period of time, obtain refills before your supply runs out.

This information is a summary only. It does not contain all information about Thioridazine . If you have questions about the medicine you are taking or would like more information, check with your doctor, pharmacist, or other health care provider.

  • Thioridazine Prescribing Information (FDA)
  • thioridazine Concise Consumer Information (Cerner Multum)
  • Mellaril Detailed Consumer Information (PDR)