Fluphenazine: Uses, Interactions and Safety

Uses

Fluphenazine is a potent phenothiazine antipsychotic. This page focuses on the long-acting decanoate injection used for continuing treatment of schizophrenia and related psychoses. The depot releases medicine over an extended period and is not interchangeable dose-for-dose with oral fluphenazine.

Administration

A healthcare professional gives the injection and plans the interval, tolerability assessment and any change from oral treatment. The reviewed Turkish Prolixin product is intramuscular. Some US decanoate labels permit intramuscular or subcutaneous administration; that permission should not be transferred to another product. Never inject the oily depot into a vein.

Safety

Movement disorders, including restlessness, muscle spasms and parkinsonism, need active monitoring. Tardive dyskinesia may persist. A depot dose continues acting after injection, so early recognition of adverse effects matters. Discuss liver or kidney disease, blood disorders, severe cardiovascular disease and prior phenothiazine reactions. It is not approved for dementia-related psychosis; antipsychotic treatment in this population increases mortality.

Interactions

Opioids and other sedatives can increase hypotension and central or respiratory depression. Alcohol should be avoided. Lithium has been associated with neurotoxicity. Antimuscarinic drugs can worsen urinary retention or constipation. QT-prolonging drugs should be avoided when possible; electrolyte-depleting drugs require review. CYP2D6 inhibitors can raise exposure. Blood pressure, glucose or warfarin monitoring may need adjustment when relevant medicines are combined.

Pregnancy and breastfeeding

Use during pregnancy requires an individualized decision. Newborns exposed late in pregnancy may need observation for movement, withdrawal, breathing or feeding problems. Breastfeeding decisions require discussion because infant safety information is limited.

Adverse effects

Reported effects include tremor, stiffness, akathisia, drowsiness, constipation and prolactin effects. Seek urgent care for fever and rigidity with confusion, fainting, breathing difficulty, severe allergy or signs of infection.

Sources

• Fluphenazine Decanoate Injection, USP – US prescribing information (Revised 04/2026; DailyMed updated 2026-08-25)
• Turkish product information: PROLIXIN DECANOATE 25 mg/ml IM prolonged-release injection
• ZYTIGA interaction information