Before using fluphenazine decanoate, tell your doctor or pharmacist if you are allergic to it; or to other phenothiazines (such as chlorpromazine, perphenazine); or if you have any other allergies. This product may contain inactive ingredients (such as sesame oil, benzyl alcohol), which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: brain damage, nervous system problems (such as CNS depression, cerebrovascular insufficiency, brain tumors, encephalitis, encephalopathy), blood problems (such as leukopenia, thrombocytopenia, agranulocytosis), liver problems, breast cancer, eye problems (such as glaucoma), heart problems (such as very high or very low blood pressure, mitral valve insufficiency), kidney problems, a certain adrenal gland tumor (pheochromocytoma), seizures, exposure to phosphorus insecticides, chronic breathing problems (such as asthma, emphysema, frequent infections), low blood calcium, enlarged prostate, drug or alcohol dependency, Reye's syndrome, dehydration.

Before having surgery or any diagnostic testing, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

This drug may make you dizzy or drowsy or blur your vision. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness or clear vision until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

This medication may make you sweat less, making you more likely to get heat stroke. Avoid doing things that may cause you to overheat, such as hard work or exercise in hot weather, or using hot tubs. When the weather is hot, drink a lot of fluids and dress lightly. If you overheat, quickly look for a place to cool down and rest. Get medical help right away if you have a fever that does not go away, mental/mood changes, headache, or dizziness.

Avoid being exposed to very cold temperatures (such as swimming in cold water). Severe lowering of your body temperature may occur.

Children may be more sensitive to the side effects of this drug, especially the side effect of uncontrolled movements. This is especially true if the child is sick (such as has chickenpox, measles, stomach flu).

Older adults may be more sensitive to the side effects of this drug, especially pain at the injection site, facial or muscle twitching, muscle spasms/stiffness, uncontrolled movements (tardive dyskinesia), drowsiness, dizziness, lightheadedness, confusion, and possible effects on blood pressure. Drowsiness, dizziness, lightheadedness, and confusion can increase the risk of falling.

During pregnancy, this medication should be used only when clearly needed. Liver problems or birth defects may occur in infants exposed to this type of medication in the womb. Tell the doctor right away if you notice yellowing of the eyes/skin or dark urine in your infant. Babies born to mothers who have used this drug during the last 3 months of pregnancy may rarely develop symptoms including muscle stiffness or shakiness, drowsiness, feeding/breathing difficulties, or constant crying. If you notice any of these symptoms in your newborn especially during their first month, tell the doctor right away.

Since untreated mental/mood problems (such as schizophrenia) can be a serious condition, do not stop taking this medication unless directed by your doctor. If you are planning pregnancy, become pregnant, or think you may be pregnant, immediately discuss with your doctor the benefits and risks of using this medication during pregnancy.

It is unknown if this medication passes into breast milk. However, similar drugs pass into breast milk. Consult your doctor before breastfeeding.