Prochlorperazine: what it treats, how to take it, side effects
Last updated September 3, 2026.
Prochlorperazine is a conventional antipsychotic used most often at low doses to control severe nausea and vomiting. You may know it as Compazine. Same molecule, two worlds: the nausea use and, at higher doses, schizophrenia and short-term anxiety.
What does it treat?
Severe nausea and vomiting - the everyday reason for the prescription - and, in tablet form at higher doses, schizophrenia symptoms and short-term anxiety that other medications could not control. Never for children under 2 or under 20 pounds.
How do you take it?
Tablets three to four times a day in adults, or a suppository twice a day when pills will not stay down - same times daily. Your doctor may start low and increase no more often than every 2 to 3 days. If you take it for schizophrenia: continue even when you feel well, and never stop suddenly - withdrawal brings nausea, vomiting, dizziness, and shakiness; the exit is supervised. Missed dose: take it when you remember unless the next one is close; never double up.
Side effects to know
- Common: dizziness or unsteadiness, blurred vision, dry mouth, stuffed nose, headache, nausea, constipation, difficulty urinating, pupil changes, and increased appetite.
- Serious - call your doctor immediately: the neuroleptic malignant syndrome pattern - fever, muscle stiffness, confusion, sweating, fast or irregular heartbeat; falling; yellowing of skin or eyes; flu-like symptoms and infection signs - sore throat, chills; and the acute muscle reactions - neck cramps, tongue sticking out of the mouth, tightness in the throat, trouble breathing or swallowing.
Who should not take it?
Older adults with dementia: antipsychotics raise the risk of death in this group, and prochlorperazine is not approved for dementia-related behavior problems. Flag glaucoma, trouble urinating or prostate issues, seizures, liver disease, and heart-rhythm problems. It sedates and lowers blood pressure - no driving until you know your response, rise slowly, and skip alcohol. If you become pregnant, call your doctor.
When is it an emergency?
Fever with stiff muscles and confusion, throat tightness or trouble swallowing, fainting, or a seizure is a 911 call. For an overdose, call Poison Control at 1-800-222-1222. Pymander's escalation routing is built and tested specifically for this class of decision; see the safety architecture working paper.
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Common questions
Isn't this an antipsychotic? Why am I taking it for nausea?
Same molecule, different job: the dopamine-blocking that treats psychosis at high doses also shuts down the brain's nausea trigger zone at low doses. Prochlorperazine's labeled uses cover both - severe nausea and vomiting is the everyday prescription, schizophrenia the high-dose one. The side-effect watch list comes from the antipsychotic family and applies at any dose, scaled by how much you take.
What is the neck-cramp, tongue-out reaction I have read about?
Acute dystonia: sudden muscle spasms - neck cramps, the tongue pushing out, throat tightness, sometimes trouble breathing or swallowing. It is startling, treatable, and a call-your-doctor-immediately item; throat involvement is an emergency. It clusters early in treatment and at higher doses. Knowing the picture in advance is what keeps it from being terrifying if it ever happens.
What is the fever-and-stiffness emergency?
Neuroleptic malignant syndrome: fever, muscle stiffness, confusion, sweating, and a fast or irregular heartbeat - a rare, dangerous reaction to this drug class. It does not wait for an appointment: 911 or the ER, and tell them exactly what you take. Rare at anti-nausea doses, real enough that the combination of fever plus rigidity on this drug is never watched at home.
Why can't I stop it suddenly?
For the nausea use at low doses, short courses rarely create the issue - but regular use does: sudden stopping brings withdrawal nausea, vomiting, dizziness, and shakiness, per MedlinePlus. For the schizophrenia use, the rule is absolute: continue even when you feel well, and every exit is a supervised taper. The same bottle, different stakes - follow the instruction tied to your use.
Why does it make me so drowsy and dizzy?
Sedation and blood-pressure drop are built into the molecule - dizziness and unsteadiness lead the common list. The adaptations: rise slowly, no alcohol, no driving until you know your response, and take it when lying low for a while is possible. Drowsiness that makes the drug unusable is worth telling your prescriber - the anti-nausea toolbox has other options.
What happens if I miss a dose of prochlorperazine?
Take it as soon as you remember, unless it is almost time for the next one - then skip it and never double up. For as-needed nausea use, the question answers itself: you take it when the nausea calls. For scheduled use, the organizer handles the streak, and doubling up is the mistake to avoid - the side effects scale with dose.