Compazine (Prochlorperazine) 5 mg and 10 mg Tablets: Prescription Dopamine Antagonist Phenothiazine Antiemetic for Severe Nausea, Vomiting, and Migraine

Information last reviewed: May 2026 — for educational purposes only.

Compazine (prochlorperazine maleate) is a prescription piperazine phenothiazine with dual applications as an antiemetic for severe nausea and vomiting, and as an antipsychotic at higher doses for the management of schizophrenia and severe anxiety. As an antiemetic, prochlorperazine is one of the most potent dopamine D2 receptor antagonists in the phenothiazine class — it acts on the chemoreceptor trigger zone (CTZ) in the medulla, blocking the dopaminergic signals that trigger the emetic reflex. It is used for severe nausea and vomiting not adequately controlled by OTC antihistamines, including nausea from chemotherapy (though newer 5-HT3 antagonists like ondansetron have largely replaced it for this purpose), surgery, migraine, and gastrointestinal illness.

What Is Prochlorperazine?

Prochlorperazine acts primarily as a D2 dopamine receptor antagonist, with additional antagonism at alpha-adrenergic and histamine H1 receptors. Its D2 blockade in the chemoreceptor trigger zone (outside the blood-brain barrier) inhibits emesis. At higher doses used for psychosis and anxiety, it also acts in the limbic system and striatum. This striatal D2 blockade is responsible for extrapyramidal side effects (EPS) — including akathisia (restless leg/uncomfortable restlessness), acute dystonia (sustained muscle contraction), and parkinsonism — which are more common with prochlorperazine than with newer antiemetics.

Prochlorperazine is available as oral tablets, suppositories, and injectable solution, providing options when the oral route is unavailable due to severe vomiting.

Prescription Status

Prochlorperazine is prescription-only in the United States. There is no OTC version. Given its EPS risk profile and potential to cause tardive dyskinesia with prolonged use, it should only be used under physician supervision. It is not approved for use in children under 2 years of age or in paediatric patients with conditions that may be worsened by CNS depression.

Strengths and Available Forms

• 5 mg tablets — standard antiemetic dose for adults: 5–10 mg three to four times daily; max 40 mg/day for non-psychotic nausea indications
• 10 mg tablets — used in higher-dose antiemetic regimens; also the lower end of antipsychotic dosing (used at 5–10 mg TID-QID for anxiety/psychosis)
• 25 mg rectal suppositories — for patients unable to take oral medication due to vomiting; one suppository every 12 hours; max 3 doses/day
• 5 mg/mL injection solution (IM/IV) — for acute severe nausea in clinical settings: 5–10 mg IM; IV administration requires dilution and slow infusion; maximum 40 mg/day
• 10 mg/12-hour extended-release spansule capsules — less commonly used extended-release oral form

Prochlorperazine should be used at the lowest effective dose for the shortest necessary duration for antiemetic use. Long-term antiemetic use is not recommended due to risk of cumulative extrapyramidal effects and tardive dyskinesia.

Price of Generic Prochlorperazine

Generic prochlorperazine tablets are available at most US pharmacies. Cost is modest with or without insurance. The suppository form is somewhat more expensive. Prochlorperazine injection is available at hospitals as a generic at very low unit cost.

Frequently Asked Questions

What are extrapyramidal side effects and how serious are they?

EPS are movement disorders caused by dopamine D2 blockade in the nigrostriatal pathway. Acute dystonia (sudden sustained muscle contraction — often affecting neck or eyes) typically occurs within hours to days of starting treatment and is treated with diphenhydramine or benztropine. Akathisia (uncomfortable inner restlessness and inability to sit still) is very distressing. Parkinsonism (tremor, rigidity, bradykinesia) can develop with ongoing use. Tardive dyskinesia (involuntary repetitive movements, typically of the mouth/face/tongue) can occur with prolonged use and may be permanent — this is the most serious concern with long-term phenothiazine antiemetic use. Inform your physician about any involuntary movements.

Is prochlorperazine still used when ondansetron (Zofran) is available?

Yes — prochlorperazine remains clinically useful and is often preferred in emergency medicine for migraine-associated nausea and vomiting, where studies have shown it performs at least as well as ondansetron and also treats the headache component (through its CNS effects). It is also useful for nausea from causes other than chemotherapy or surgery. Cost is also lower than ondansetron, making it a practical alternative in resource-limited settings.

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