• If you are allergic to anything, including medicines, dyes, additives, or foods.

• If you have ever had seizures, have an abnormal EEG (brain waves) or are taking anti-seizure medicines. This drug may raise your risk of seizures.

• If you have prostate enlargement or glaucoma. This drug can worsen your symptoms.

• If you have asthma or emphysema (breathing problems). Thiethylperazine can worsen symptoms of these conditions.

• If you will be exposed to extreme heat while taking thiethylperazine. It can raise the risk of low blood pressure and other side effects.

• If you have an abnormal heart rhythm, heart block, heart failure, or any heart problem. Thiethylperazine can lower the blood pressure and cause falling or fainting.

• If you take tranquilizers (sedatives) such as diazepam (Valium) or drink alcohol. Thiethylperazine may increase the sleepiness linked to these substances.

• If you have any medical conditions such as kidney disease, liver disease (including hepatitis), or diabetes. These conditions may require that your medicine dose, regimen, or timing be changed.

• If you have Parkinson's disease. This drug may increase your risk of uncontrolled movements.

• If you are pregnant, trying to get pregnant, or if there is any chance of pregnancy. There may be an increased risk of harm to the fetus if a woman takes this drug during pregnancy.

• If you are breast-feeding. It is not known if this drug passes into breast milk. If it does, it may harm the baby.

• About any other prescription or over-the-counter medicines you are taking, including vitamins and herbs.

Epinephrine may lower the blood pressure (rather than raise it) if it is taken with thiethylperazine. Your doctor can substitute another drug if epinephrine's effects are needed.

Quinidine may increase thiethylperazine's effects on the heart.

Tricyclic antidepressants (amitriptyline, clomipramine, desipramine, doxepin, imipramine, and others) can worsen side effects of thiethylperazine.

Contrast agents ("dye") used for special x-rays may increase the risk of seizure.

Substances that make you sleepy, such as alcohol, tranquilizers, opioid pain relievers, anesthetics, and sleeping pills will make you much sleepier and may cause serious harm when taken with thiethylperazine.

Check with your doctor, nurse, or pharmacist about whether any of the medicines, vitamins, herbs, and supplements you are taking can cause problems with thiethylperazine.

Be careful getting up, changing position, or walking. Start slowly and hold onto something or someone to hold you steady. Have a responsible adult with you until you know how the medicine will affect you and that you can take care of yourself.

Thiethylperazine may cause unplanned movements called extrapyramidal effects. These include restlessness, tremors, sticking out the tongue, muscle tightness, and involuntary muscle contractions or spasms. Let your doctor or nurse know right away if this happens. These side effects can usually be stopped by other medicines such as diphenhydramine (Benadryl). In some cases, it may be necessary to stop the thiethylperazine.

Call your doctor or nurse right away if you have restlessness, muscle stiffness, severe anxiety, slow jerky movements, tiredness, weakness, fever, confusion, trouble walking, irregular or fast heartbeat, or yellow eyes or skin.

At higher doses over long periods, thiethylperazine can cause a movement problem called tardive dyskinesia. If you notice repeated instances of puffing out of cheeks, puckering of the mouth, grimacing, chewing movements, or sticking out the tongue, contact the doctor or nurse right away. Stopping the drug quickly may allow these problems to go away.

If you are scheduled for special x-rays, be sure your radiologist knows you are taking thiethylperazine. You may need to stop taking it 48 hours before the study and hold off starting back on it for at least 24 hours afterward.

Thiethylperazine may raise your risk of seizures if you have had them before.

• drowsiness
• sleepiness
• dry mouth
• constipation

• low blood pressure
• blurred vision
• restlessness
• involuntary muscle movements or spasms (extrapyramidal effects)*
• tremors
• dizziness
• ringing in the ears (tinnitus)

• increased heart rate
• changes in electrical activity of heart (EKG changes)
• low blood pressure when first sitting or standing up, with dizziness or fainting*
• severe allergic reaction with itching, hives (skin welts), dizziness, trouble breathing or swallowing, swelling of the mouth, tongue, or face
• low white blood count with increased risk of infection
• tardive dyskinesia (involuntary movements that may become permanent)*

*See "Precautions" section for more detailed information.