How does this medication work? What will it do for me?

Fluphenazine decanoate belongs to the family of medications known as antipsychotics, more specifically, the phenothiazines. This medication is used to treat schizophrenia. It is thought to work by reducing dopamine (a chemical messenger) in certain areas of the brain. The effects of this medication on symptoms of schizophrenia begin to appear within 48 to 96 hours after being injected.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are using this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

This medication is available as a 25 mg/mL and 100 mg/mL injectable.

How should I use this medication?

This medication is given as an intramuscular (into the muscle) injection at your doctor's office or clinic on a regular basis (usually every 2 to 3 weeks). The dose depends on the individual person being treated, and will be determined by your doctor. Seniors may require lower doses.

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important that this medication be given exactly as recommended by your doctor. If you miss an appointment to receive fluphenazine decanoate, contact your doctor as soon as possible to reschedule your appointment.

Any unused medication should be discarded 28 days after first puncturing the vial.

This medication is stored at room temperature and protected from light. Freezing and extreme heat should be avoided. Keep out of the reach of children.

This medication is available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms listed here. The forms available for the specific brand you have searched are listed under "What form(s) does this medication come in?"

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

You should not receive fluphenazine decanoate if you:

  • are allergic to fluphenazine decanoate, other phenothiazine medications (e.g., prochlorperazine, chlorpromazine), or any ingredients of the medication
  • are taking large doses of CNS depressant medications such as alcohol, sedatives (e.g., lorazepam, diazepam), or narcotics (e.g., codeine, oxycodone, hydromorphone)
  • have blood disorders
  • have serious heart, brain, or kidney disease
  • have suspected or documented brain damage or hardening of the arteries in the brain
  • have liver damage
  • has severe central nervous system (CNS) depression that can cause decreased heart rate and breathing

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is used in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who uses this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people using this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • changes in menstrual period
  • constipation
  • decreased sexual ability
  • decreased sweating
  • dizziness
  • drowsiness or fatigue
  • dryness of mouth
  • headache
  • nausea
  • rough tongue
  • stuffy nose
  • swelling or pain in breasts
  • unusual secretion of milk
  • unusual weight changes
  • watering of mouth

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • blurred vision, change in colour vision, or difficulty seeing at night
  • difficult urination
  • loss of balance control
  • "mask"-like face
  • severe restlessness or need to keep moving
  • severe sunburn
  • shuffling walk
  • signs of bleeding (e.g., bloody nose, blood in urine, coughing blood, cuts that don't stop bleeding)
  • signs of liver problems (e.g., nausea, vomiting, diarrhea, loss of appetite, weight loss, yellowing of the skin or whites of the eyes, dark urine, pale stools)
  • signs of movement disorders
    • inability to move eyes
    • increased blinking or spasms of eyelid
    • lip smacking or puckering
    • muscle spasms of the face, neck, body, arms, or legs causing unusual postures or unusual expressions on face
    • puffing of cheeks
    • rapid or worm-like movements of the tongue
    • sticking out of tongue
    • trouble breathing, speaking, or swallowing
    • twitching movements
    • uncontrolled chewing movements
    • uncontrolled movements of arms or legs
    • uncontrolled twisting movements of neck, trunk, arms, or legs
  • skin rash
  • stiffness of arms and legs
  • symptoms of infection (e.g., fever or chills, severe diarrhea, shortness of breath, prolonged dizziness, headache, stiff neck, weight loss, or listlessness)

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • signs of a serious allergic reaction (e.g., hives, difficulty breathing, or swelling of the face and throat)
  • signs of abnormal heart rhythm (e.g., rapid heartbeat, chest pain, fainting)
  • symptoms of neuroleptic malignant syndrome
    • difficult or fast breathing
    • fast heartbeat
    • fever
    • high or low blood pressure
    • increased sweating
    • loss of bladder control
    • severe confusion or coma
    • severe muscle stiffness
    • trembling or shaking
    • trouble speaking or swallowing

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Abnormal heart rhythm: This medication may cause or increase the risk for a certain type of abnormal heart rhythm called QT prolongation. Other medications can also increase the risk of QT prolongation when taken together with fluphenazine decanoate. If you experience symptoms of an abnormal heart rhythm such as dizziness, heart palpitations (fast, pounding, or irregular heartbeat), fainting, or seizures, stop taking this medication and get immediate medical attention.

Blood counts: This medication can decrease the number of neutrophils (a type of white blood cell that helps fight infection) and platelets (which help your blood to clot). Your doctor will do blood tests to monitor this. If you notice any signs of infection (e.g., fever, chills, or sore throat) or unusual bleeding or bruising, contact your doctor immediately.

Drowsiness/reduced alertness: Especially in the first few days of treatment, this medication may impair the mental and physical abilities required for driving a car or operating heavy machinery. Avoid these activities until you know this medication does not affect your ability to perform them safely. Avoid drinking alcohol while using this medication, as it can produce extreme drowsiness.

Heat exposure and sweating: Fluphenazine decanoate may prevent the body from cooling when overheated by reducing your ability to sweat. Avoid becoming overheated when using fluphenazine decanoate.

Involuntary movement: Like other medications to control symptoms of schizophrenia, fluphenazine decanoate may cause rhythmic involuntary movements, known as tardive dyskinesia. Tardive dyskinesia is more likely to occur in women and seniors. These movements may involve only the tongue, face, mouth, or jaw, or they may include the extremities and trunk. Tardive dyskinesia is not reversible for some people. Report involuntary movements including sticking out the tongue, puckering mouth, or chewing movements to your doctor as soon as possible.

Kidney function: Fluphenazine decanoate may cause decreased kidney function and should not be used by people with kidney disease. Your doctor may want to regularly monitor your kidney function with blood tests when you first start taking fluphenazine decanoate to monitor for reduced kidney function.

Liver problems: Fluphenazine decanoate may cause liver problems. Your doctor may want to test your liver function with blood tests regularly while you are taking this medication. If you notice any signs of liver problems such as yellowing of the skin or whites of the eyes, nausea, vomiting, diarrhea, loss of appetite, weight loss, dark urine, or pale stools, contact your doctor as soon as possible.

Low blood pressure: This medication can cause low blood pressure. If you have heart disease, disorders of the blood vessels in the brain, or are having surgery, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Neuroleptic malignant syndrome: Very rarely, fluphenazine decanoate has been reported to cause a severe reaction called neuroleptic malignant syndrome. If you or someone in your family who is being given fluphenazine decanoate develops symptoms including high body temperature (above 38°C), sweating, rapid heartbeat, severe muscle stiffness, and change in alertness, seek emergency help immediately.

Seizure disorders: Seizures have been reported by people who are taking fluphenazine decanoate. If you have seizure disorders, discuss with your doctor how this medication may affect your medical condition, how your medical condition may affect the dosing and effectiveness of this medication, and whether any special monitoring is needed.

Sun: This medication makes you more sensitive to the harmful effects of sunlight.

Tremor and stiffness: As with other medications used to treat schizophrenia, fluphenazine decanoate may cause tremors or stiffness, or difficulty beginning purposeful movement. If this occurs, report it to your doctor as soon as possible.

Vision changes: Fluphenazine decanoate has been reported to cause changes in vision. Tell your doctor about any changes as soon as possible.

Withdrawal: Suddenly stopping this medication can cause withdrawal symptoms such as nausea, vomiting, dizziness, and shaking. Do not stop using this medication unless recommended by your doctor.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: It is not known if fluphenazine decanoate passes into breast milk. If you are a breast-feeding mother and are taking this medication, it may affect your baby. Talk to your doctor about whether you should continue breast-feeding.

Children: The safety and effectiveness of this medication have not been established for children.

Seniors: Seniors with dementia may be more at risk of stroke and mini-strokes while using this medication. They are also more likely to experience side effects. Smaller doses of this medication are usually needed for seniors.

What other drugs could interact with this medication?

There may be an interaction between fluphenazine decanoate and any of the following:

  • ACE inhibitors (e.g., ramipril, enalapril, captopril)
  • alcohol
  • amphetamines (e.g., dextroamphetamine)
  • antacids
  • antihistamines that cause drowsiness (e.g., diphenhydramine)
  • antiseizure medications (e.g., phenytoin, carbamazepine)
  • barbiturates (e.g., phenobarbital, butalbital)
  • benzodiazepines (e.g., alprazolam, clonazepam, diazepam, lorazepam)
  • beta-blockers (e.g., atenolol, carvedilol, propranolol)
  • bromocriptine
  • chlorpromazine
  • cimetidine
  • clonidine
  • epinephrine
  • fluoxetine
  • guanethidine
  • imatinib
  • levodopa
  • lithium
  • medications used to aid sleep
  • medications used to treat diabetes (e.g., insulin, metformin, glyburide)
  • narcotic pain medication (e.g., codeine, morphine, oxycodone)
  • norfluoxetine
  • other antidepressant or anti-anxiety medications
  • other medications that may make you drowsy
  • paroxetine
  • pramipexole
  • pseudoephedrine
  • quinidine
  • quinolone antibiotics (e.g., moxifloxacin)
  • ropinirole
  • sotalol
  • tacrolimus
  • tricyclic antidepressants (e.g., amitriptyline, imipramine, nortriptyline)
  • warfarin

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.