Compazine Side Effects: What to Expect and When to Call Your Doctor

Like all medications, Compazine (prochlorperazine) can cause side effects. Most people tolerate it well, especially at the low doses used for nausea and vomiting. But there are some serious side effects to be aware of — particularly with long-term use or higher doses used for psychiatric conditions. This guide explains what to expect and when to seek medical attention.

Common Side Effects of Compazine (Prochlorperazine)

These side effects are relatively common, especially when you first start taking prochlorperazine. They often improve as your body adjusts to the medication:

Drowsiness and sedation — the most frequently reported side effect; avoid driving or operating heavy machinery until you know how the drug affects you

Dizziness — especially when standing up quickly (orthostatic hypotension); rise slowly from sitting or lying positions

Dry mouth — common anticholinergic effect; drinking water, sugar-free gum, or saliva substitutes may help

Constipation — another anticholinergic effect; increase fiber and fluid intake if this occurs

Blurred vision — usually temporary; tell your doctor if it persists

Low blood pressure on standing — can cause lightheadedness; older adults are particularly susceptible

Extrapyramidal Symptoms (EPS): Call Your Doctor Promptly

Extrapyramidal symptoms are movement-related side effects caused by prochlorperazine's blockade of dopamine receptors. These can occur even at doses used for nausea. If you develop any of these, call your doctor right away:

Acute dystonia: Sudden, involuntary muscle contractions — often affecting the neck, jaw, or eyes (painful eye-rolling upward is called oculogyric crisis). This is a medical emergency. Go to the emergency room.

Akathisia: Restlessness, an inner sense of needing to move constantly; you may feel unable to sit still. Call your doctor.

Parkinsonism: Tremor, muscle stiffness, slow movements, or shuffling gait that mimic Parkinson's disease. Call your doctor.

Tardive Dyskinesia: A Serious Long-Term Risk

Tardive dyskinesia (TD) is a potentially irreversible movement disorder characterized by repetitive, involuntary movements — most commonly of the face, lips, tongue, and jaw (lip smacking, tongue rolling, facial grimacing). It can also affect the arms, legs, and trunk.

TD is most likely to develop with long-term use (months to years), higher doses, or in older patients and women. Early detection is critical because stopping the medication may allow partial or complete recovery — but in some cases, the movements persist even after discontinuation.

What to do: If you notice any unusual movements — especially around the mouth, face, or tongue — contact your doctor immediately. Do not stop the medication abruptly without medical guidance, as this can worsen symptoms temporarily.

Neuroleptic Malignant Syndrome (NMS): Rare but Life-Threatening

Neuroleptic Malignant Syndrome (NMS) is a rare but potentially fatal reaction to antipsychotic medications including prochlorperazine. Symptoms include:

High fever (often above 104 degrees F)

Severe muscle rigidity

Confusion or altered consciousness

Rapid heart rate and sweating

What to do: Call 911 or go to the emergency room immediately. NMS is a medical emergency.

Other Serious Side Effects to Watch For

Blood disorders: Prochlorperazine can temporarily lower white blood cell counts. Signs include fever, chills, sore throat, or unusual infections. Contact your doctor if these develop.

Severe allergic reactions: Hives, facial swelling, or difficulty breathing. Seek emergency care immediately.

Jaundice: Yellowing of skin or eyes suggesting liver toxicity. Contact your doctor right away.

QT prolongation: Prochlorperazine can affect heart rhythm. If you have heart disease or take other QT-prolonging drugs, discuss this risk with your doctor before starting prochlorperazine.

Who Is at Higher Risk for Side Effects?

Older adults — higher risk of EPS, orthostatic hypotension, and falls

Patients with dementia — prochlorperazine should NOT be used to treat behavioral problems in elderly patients with dementia due to increased mortality risk

Patients with Parkinson's disease — dopamine-blocking drugs worsen motor symptoms; avoid prochlorperazine in this population

Patients with heart disease or long QT syndrome — increased cardiac risk

For a full review of drug interactions to discuss with your doctor, see our guide: Compazine Drug Interactions: What to Avoid and What to Tell Your Doctor.