Thioridazine - Uses, Side Effects, and More

What are the most common side effects of thioridazine?

The most common side effects of thioridazine are listed below. Tell your healthcare provider if you have any of these side effects that bother you.

• Blurred vision
• Constipation
• Drowsiness
• Dry mouth
• Restlessness

There may be other side effects of thioridazine that are not listed here. Contact your healthcare provider if you think you are having a side effect of a medicine. In the U.S., you can report side effects to the FDA at www.fda.gov/medwatch or by calling 800-FDA-1088. In Canada, you can report side effects to Health Canada at www.health.gc.ca/medeffect or by calling 866-234-2345.

What are the serious side effects of thioridazine?

While less common, the most serious side effects of thioridazine are described below, along with what to do if they happen.

Severe Allergic Reactions. Thioridazine may cause allergic reactions, which can be serious. Stop taking thioridazine and get help right away if you have any of the following symptoms of a serious allergic reaction.

• Breathing problems or wheezing
• Racing heart
• Fever or general ill feeling
• Swollen lymph nodes
• Swelling of the face, lips, mouth, tongue, or throat
• Trouble swallowing or throat tightness
• Itching, skin rash, or pale red bumps on the skin called hives
• Nausea or vomiting
• Dizziness, feeling lightheaded, or fainting
• Stomach cramps
• Joint pain

Heart Rhythm Changes. Thioridazine may cause a rare, dangerous heart rhythm problem called QT prolongation and torsade de pointes. Some people have a higher risk of this, including people who are older, have other people in their family who have had these conditions, have low potassium or magnesium levels, or who take medicines that can prolong the QT interval. Tell your healthcare provider right away if you faint or have changes in your heart rate or rhythm, such as a fast or skipping heartbeat.

Parkinson-like Symptoms. Thioridazine may cause involuntary movement problems, including shakiness, stiffness, or jerkiness. It can also cause drooling, falling, or walking or balance problems. These are called Parkinson-like symptoms, or parkinsonism. Call your healthcare provider right away if you develop any Parkinson-like symptoms.

Uncontrolled Movements. Thioridazine can cause some people to have movements that they cannot control. This condition, called tardive dyskinesia (TD), can cause jerky movements of your face, tongue, or body. TD can be permanent. Call your healthcare provider right away if you have any symptoms of TD.

• Tongue sticking out
• Lip smacking or puckering
• Grimacing
• Rapid eye blinking
• Jerking or twisting motion of the arms, legs, or trunk

Neuroleptic Malignant Syndrome (NMS). Antipsychotic medicines, like thioridazine, can cause a rare but serious condition called neuroleptic malignant syndrome. NMS can lead to death. Stop taking thioridazine and call your healthcare provider right away if you have any of the following symptoms.

• High fever
• Muscle stiffness or rigidity, where it is hard to move
• Changes in your breathing or heart rate
• Increased sweating
• Confusion

Blood Disorders. Thioridazine can cause blood disorders, such as agranulocytosis, low neutrophil levels (neutropenia), and low white blood cell levels (leukopenia). Keep all appointments to have your blood checked. Call your healthcare provider right away if you have any of the following symptoms of blood disorders.

• Fever, chills, or sweats
• Sore throat, cough, or shortness of breath
• Frequent infection
• Unusual weakness or tiredness
• Sores in your mouth or throat
• Swollen lymph nodes

High Prolactin Level (Hyperprolactinemia). Thioridazine may cause an increased level of the hormone prolactin in your blood. Increased levels of prolactin could lead to fertility or bone problems. Contact your healthcare provider if you have any of the following symptoms.

• Vaginal dryness
• Irregular or no periods
• Production of breastmilk when not pregnant or nursing
• Inability to get or keep an erection
• Enlarged breast size (gynecomastia)
• Decreased muscle and body hair

Low Blood Pressure Upon Standing (Orthostatic Hypotension) and Falls. Thioridazine may cause a sudden drop in blood pressure when standing up. To help prevent this, be careful not to get up too quickly. If you feel faint or dizzy, lie down right away until the dizziness stops, then take your time getting up again. Tell your healthcare provider right away if you have any of the following symptoms of orthostatic hypotension.

• Dizziness, feeling lightheaded, or fainting
• Blurred vision
• Confusion
• Feeling weak or tired

Seizures. Some people who have taken thioridazine have reported having seizures. There are many different types of seizures and some of them are not easy to recognize. Stop taking thioridazine and call your healthcare provider if you have any of the following signs that a seizure is happening or could happen.

• Muscle twitching, jerking, spasms, tremors, or other uncontrolled movements
• Stiffening of your arms and legs
• Feeling anxious, nervous, confused, or a sense of dread
• Feeling dizzy or lightheaded
• Falling or losing consciousness

Eye Effects. Thioridazine may have effects on your eyes, such as deposits on the cornea and lens. This may be more likely if you take higher doses of thioridazine, or if you take thioridazine for a longer period of time. Your healthcare provider may recommend that you have your eyes examined regularly while taking thioridazine. Tell your healthcare provider right away if you have eye discomfort or changes in your vision.