Fluphenazine, sold under the brand Prolixin in the US and Modecate in some other countries, is a high-potency piperazine phenothiazine antipsychotic. It was introduced in 1959 as oral tablets and shortly afterwards as a long-acting decanoate injection — one of the first depot antipsychotics in the world. Both forms are still used in 2026 for schizophrenia, particularly in patients for whom adherence to daily oral medication is a challenge.
Fluphenazine is a high-potency phenothiazine antipsychotic available as oral tablets, an oral concentrate, an immediate-release injection, and a long-acting decanoate depot — making it one of the most flexible delivery options among the first-generation antipsychotics.
FDA-approved indication
Per the DailyMed fluphenazine labelling, the indication is the management of schizophrenia. Fluphenazine is not approved for behavioural disturbances in children, dementia-related psychosis, or non-psychotic anxiety.
How it works
Strong dopamine D2 receptor blockade is the basis of the antipsychotic effect. Compared with low-potency phenothiazines, fluphenazine has minimal antihistamine, anticholinergic, and alpha-1 adrenergic blockade, which is why doses are in the milligrams and why sedation and dry mouth are less prominent than with chlorpromazine. The trade-off is that EPS rates are among the highest of any antipsychotic.
Oral fluphenazine: dosing
Per the FDA label, oral doses for schizophrenia typically range from 2.5 to 10 mg per day in divided doses, with maintenance often at 1 to 5 mg per day. Higher doses (up to 40 mg/day) have been used in severe cases. Older adults are started at much lower doses.
Fluphenazine decanoate: the depot
Fluphenazine decanoate is fluphenazine esterified with decanoic acid and dissolved in sesame oil. After intramuscular injection, the ester is slowly hydrolysed to release fluphenazine into the bloodstream over weeks. Typical dosing is 12.5 to 25 mg every 2 to 3 weeks, with adjustments based on individual response and tolerability. Some patients are stable on monthly dosing.
The advantages and trade-offs are described in our LAI vs oral antipsychotics guide and our fluphenazine decanoate overview. The short version: depot dosing dramatically improves adherence, but it removes the option to stop or rapidly adjust the medication if a problem develops.
Conversion from oral to depot
There is no exact mathematical formula. A common rule of thumb is that 12.5 mg of fluphenazine decanoate every 2 weeks is roughly equivalent to 10 mg/day of oral fluphenazine, but individual variation is large. Starting depot doses are usually conservative, with oral overlap during the first few weeks. The conversion process is best done by a prescriber experienced with depot antipsychotics.
Side effects
Movement effects
Acute dystonia (often within hours or days of starting), parkinsonism, and akathisia are common. Many prescribers co-prescribe an anticholinergic such as benztropine prophylactically when starting fluphenazine. Tardive dyskinesia risk accumulates with long-term use.
Sedation, anticholinergic, orthostatic effects
Generally mild — less than with low-potency phenothiazines.
Hyperprolactinemia
Substantial. Sexual dysfunction, menstrual changes, breast changes, and bone density concerns over years.
Cardiovascular
QT prolongation can occur. Orthostatic hypotension is less marked than with chlorpromazine.
Hepatic and haematologic
Rare but serious cholestatic jaundice and blood dyscrasias have been reported as class effects.
Injection site reactions (depot)
Pain, redness, induration, and occasionally a small lump at the injection site. Rotating sites helps.
Severe muscle stiffness with high fever and confusion, sudden severe involuntary movements, fainting, or signs of an allergic reaction.
Boxed warning
Standard antipsychotic boxed warning — increased mortality in elderly patients with dementia-related psychosis. Fluphenazine is not for behavioural symptoms of dementia.
Drug interactions
Additive sedation with CNS depressants. Additive QT effects with other QT-prolonging drugs. Lowered seizure threshold. Always disclose all medications and supplements.
Where fluphenazine fits in 2026
Newer second-generation depots (paliperidone palmitate, aripiprazole monohydrate, risperidone formulations) have largely displaced fluphenazine decanoate as first-line in high-income settings, primarily because of lower EPS rates. Fluphenazine still has a role:
- Patients who have done well historically and want to continue
- Settings where cost is a major factor — generic fluphenazine decanoate is among the cheapest depot options globally
- Cases where second-generation depots have not worked or have been poorly tolerated
- Cases where the clinician needs reliable D2 blockade without metabolic burden
In low- and middle-income settings, fluphenazine decanoate remains a workhorse depot antipsychotic.
Practical questions to ask your prescriber
- What is the rationale for fluphenazine specifically?
- Should we start oral, depot, or both?
- Will I need an anticholinergic alongside?
- What is the AIMS exam schedule for monitoring tardive dyskinesia?
- How do depot doses get adjusted if my response changes?
The big picture
Fluphenazine is one of the older drugs that did not get retired. Its depot form, in particular, has helped people maintain stability for decades when other approaches were not workable. The EPS burden is real, and newer depot options often have a softer profile. But for the right patient and the right setting, fluphenazine remains a useful and well-understood medication. The conversation about fit is best had with a prescriber familiar with the trade-offs.
This article is for educational purposes only and is not medical advice. Information is summarised from publicly available FDA labelling, regulatory sources, and peer-reviewed literature. Always consult your prescribing clinician before starting, stopping, or changing any medication.