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Generic name: thioridazineTHYE-oh-RID-a-zeen ]
Drug class: Phenothiazine antipsychotics

Medically reviewed by on Aug 3, 2023. Written by Cerner Multum.

What is Mellaril?

Mellaril is a phenothiazine (FEEN-oh-THYE-a-zeen) antipsychotic medicine that is used to treat schizophrenia.

Mellaril is usually given after other treatments have failed.

Mellaril may also be used for purposes not listed in this medication guide.

Mellaril side effects

Get emergency medical help if you have signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

High doses or long-term use of thioridazine can cause a serious movement disorder that may not be reversible. The longer you use Mellaril, the more likely you are to develop this disorder, especially if you are a woman or an older adult.

Mellaril may cause serious side effects. Call your doctor at once if you have:

  • uncontrolled muscle movements in your arms, legs, or face (chewing, lip smacking, frowning, tongue movement, blinking or eye movement);

  • fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out);

  • agitation, confusion;

  • seizure (convulsions);

  • decreased night vision, tunnel vision, watery eyes, increased sensitivity to light;

  • little or no urinating;

  • low white blood cell counts--fever, chills, mouth sores, skin sores, sore throat, cough, trouble breathing, feeling light-headed; or

  • severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Common side effects of Mellaril may include:

  • drowsiness;

  • dry mouth, blurred vision;

  • nausea, vomiting, constipation, diarrhea;

  • breast swelling or discharge;

  • changes in your menstrual periods; or

  • swelling in your hands or feet.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


You should not use Mellaril if you have a heart rhythm disorder, a history of long QT syndrome, untreated or uncontrolled high blood pressure, very low blood pressure, or if you have drowsiness, slow breathing, weak pulse, or decreased alertness.

Mellaril is not approved for use in older adults with dementia-related psychosis.

Mellaril can cause a serious heart problem, especially if you also use certain other medicines for infections, asthma, heart problems, high blood pressure, depression, mental illness, cancer, malaria, or HIV. Tell your doctor about all your current medicines and any you start or stop using.

Before taking this medicine

You should not use Mellaril if you are allergic to it, or if you have:

  • heart problems;

  • long QT syndrome (in you or a family member);

  • untreated or uncontrolled high blood pressure;

  • very low blood pressure; or

  • if you have drowsiness, slow breathing, weak pulse, or decreased alertness (such as after drinking alcohol or taking medicines that make you sleepy).

Mellaril can cause a serious heart problem. Your risk may be higher if you also use certain other medicines. Your doctor may change your treatment plan if you also use:

  • antibiotics;

  • antidepressants;

  • blood pressure medicine;

  • cancer medicine;

  • certain HIV/AIDS medicines;

  • heart rhythm medicine;

  • medicine to treat or prevent malaria; or

  • other antipsychotic medicines.

Tell your doctor if you have ever had:

  • heart problems, high blood pressure;

  • slow heartbeats that have caused you to faint;

  • breast cancer;

  • liver or kidney disease;

  • seizures;

  • Parkinson's disease;

  • enlarged prostate or urination problems;

  • low levels of potassium in your blood (hypokalemia); or

  • a serious side effect while using Mellaril or another phenothiazine.

Tell your doctor if you are pregnant or if you become pregnant. Taking antipsychotic medicine in the last 3 months of pregnancy may cause breathing problems, feeding problems, or withdrawal symptoms in the newborn.

It may not be safe to breastfeed while using Mellaril. Ask your doctor about any risk.

How should I take Mellaril?

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

You will need frequent medical tests. Your heart function may need to be checked using an electrocardiograph or ECG (sometimes called an EKG).

If you need surgery, tell the surgeon ahead of time that you are using Mellaril.

Store at room temperature away from moisture, heat, and light.

What happens if I miss a dose?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

What happens if I overdose?

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

What should I avoid while taking Mellaril?

Avoid driving or hazardous activity until you know how Mellaril will affect you. Dizziness or drowsiness can cause falls, accidents, or severe injuries.

Avoid getting up too fast from a sitting or lying position, or you may feel dizzy.

Avoid drinking alcohol. Dangerous side effects could occur.

What other drugs will affect Mellaril?

Taking Mellaril with other drugs that make you sleepy or slow your breathing can cause dangerous or life-threatening side effects. Ask your doctor before using opioid medication, a sleeping pill, a muscle relaxer, or medicine for anxiety or seizures.

Many drugs can affect Mellaril, and some drugs should not be used at the same time. Tell your doctor about all your current medicines and any medicine you start or stop using. This includes prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed here.

Further information

Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.