Fluoxetine is a medicine used to treat many types of mental health disorders, including:

Depression
Obsessive-compulsive disorder (OCD)
Eating disorders
Panic attacks

It’s also taken to relieve symptoms of premenstrual dysphoric disorder, which may include irritability, mood swings, bloating, and breast tenderness. Additionally, this medicine is sometimes used with olanzapine (Zyprexa) to treat depression caused by bipolar disorder.

Fluoxetine is in a class of drugs called selective serotonin reuptake inhibitors (SSRIs). It works by boosting the amount of a natural substance in the brain called serotonin.

The U.S. Food and Drug Administration (FDA) approved fluoxetine in 1987. It’s sold under the brand name Prozac.

warnings

What is the most important information I should know about Prozac (Fluoxetine)?

You should not use fluoxetine if you are allergic to it, if you also take pimozide or thioridazine.

Do not use fluoxetine if you have used an MAO inhibitor in the past 14 days. A dangerous drug interaction could occur. MAO inhibitors include isocarboxazid, linezolid, methylene blue injection, phenelzine, rasagiline, selegiline, and tranylcypromine. You must wait at least 14 days after stopping an MAO inhibitor before you take fluoxetine. You must wait 5 weeks after stopping fluoxetine before you can take thioridazine or an MAOI.

Tell your doctor about all other antidepressants you take, especially Celexa, Cymbalta, Desyrel, Effexor, Lexapro, Luvox, Oleptro, Paxil, Pexeva, Symbyax, Viibryd, or Zoloft.

Tell your doctor if you have ever had:

cirrhosis of the liver;
urination problems;
diabetes;
narrow-angle glaucoma;
seizures or epilepsy;
sexual problems;
bipolar disorder (manic depression);
drug abuse or suicidal thoughts; or
electroconvulsive therapy (ECT).

Some young people have thoughts about suicide when first taking an antidepressant. Your doctor should check your progress at regular visits. Your family or other caregivers should also be alert to changes in your mood or symptoms.

Older adults may be more sensitive to the effects of this medicine.

Ask your doctor about taking this medicine if you are pregnant. Taking an SSRI antidepressant during late pregnancy may cause serious medical complications in the baby. However, you may have a relapse of depression if you stop taking your antidepressant. Tell your doctor right away if you become pregnant. If you are pregnant, your name may be listed on a pregnancy registry to track the effects of fluoxetine on the baby.

If you are breastfeeding, tell your doctor if you notice agitation, fussiness, feeding problems, or poor weight gain in the nursing baby.

Fluoxetine is not approved for use by anyone younger than 18 years old.

Side Effects

What are the side effects of Prozac (Fluoxetine)?

Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).

Report any new or worsening symptoms to your doctor, such as: mood or behavior changes, anxiety, panic attacks, trouble sleeping, or if you feel impulsive, irritable, agitated, hostile, aggressive, restless, hyperactive (mentally or physically), more depressed, or have thoughts about suicide or hurting yourself.

Call your doctor at once if you have:

blurred vision, tunnel vision, eye pain or swelling, or seeing halos around lights;
fast or pounding heartbeats, fluttering in your chest, shortness of breath, and sudden dizziness (like you might pass out);
low levels of sodium in the body--headache, confusion, slurred speech, severe weakness, vomiting, loss of coordination, feeling unsteady; or
severe nervous system reaction--very stiff (rigid) muscles, high fever, sweating, confusion, fast or uneven heartbeats, tremors, feeling like you might pass out.

Seek medical attention right away if you have symptoms of serotonin syndrome, such as: agitation, hallucinations, fever, sweating, shivering, fast heart rate, muscle stiffness, twitching, loss of coordination, nausea, vomiting, or diarrhea.

Common side effects may include:

sleep problems (insomnia), strange dreams;
headache, dizziness, drowsiness, vision changes;
tremors or shaking, feeling anxious or nervous;
pain, weakness, yawning, tired feeling;
upset stomach, loss of appetite, nausea, vomiting, diarrhea;
dry mouth, sweating, hot flashes;
changes in weight or appetite;
stuffy nose, sinus pain, sore throat, flu symptoms; or
decreased sex drive, impotence, or difficulty having an orgasm.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

Pregnancy & Breastfeeding

Can I take Prozac (Fluoxetine) if I’m pregnant or breastfeeding?

Risk cannot be ruled out

Based on FDA pregnancy categories

If you are breastfeeding, tell your doctor if you notice agitation, fussiness, feeding problems, or poor weight gain in the nursing baby.

Dosage Guidelines & Tips

How to take Prozac (Fluoxetine)?

Use Prozac (Fluoxetine) exactly as directed on the label, or as prescribed by your doctor. Do not use in larger or smaller amounts or for longer than recommended.

Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose. Use the medicine exactly as directed.

Swallow the delayed-release capsule whole and do not crush, chew, break, or open it.

Measure liquid medicine carefully. Use the dosing syringe provided, or use a medicine dose-measuring device (not a kitchen spoon).

It may take up to 4 weeks before your symptoms improve. Keep using the medication as directed and tell your doctor if your symptoms do not improve.

Tell your doctor if you have any changes in sexual function, such as loss of interest in sex, trouble having an orgasm, or (in men) problems with erections or ejaculation. Some sexual problems can be treated.

Do not stop using fluoxetine suddenly, or you could have unpleasant withdrawal symptoms. Ask your doctor how to safely stop using fluoxetine.

Store at room temperature away from moisture and heat.

What should I do if I missed a dose of Prozac (Fluoxetine)?

Take the medicine as soon as you can, but skip the missed dose if it is almost time for your next dose. Do not take two doses at one time.

If you miss a dose of Prozac Weekly, take the missed dose as soon as you remember and take the next dose 7 days later. However, if it is almost time for the next regularly scheduled weekly dose, skip the missed dose and take the next one as directed. Do not take extra medicine to make up the missed dose.

What to Expect

Fluoxetine won’t change your personality, but it should help you feel more like yourself.

You will likely see the full benefits of fluoxetine after about four to six weeks of treatment.

It takes about one week for fluoxetine levels to build up in your body and then a few weeks after that for your body to adapt.

Don’t stop using this drug without talking to your doctor, even if it doesn’t seem to help at first.