Fluoxetine: What It's Used For and Common Side Effects

In this article...
  • Fluoxetine, also known as Prozac, is a common antidepressant. Learn how this medication treats depression and other conditions, and find out about possible side effects.

Fluoxetine is the generic name of an antidepressant medication used to treat a variety of conditions, including depression and mood or behavioral disorders. It's available under the brand name Prozac and is typically covered through Medicare prescription drug plans.

What Is Fluoxetine Used For?

Fluoxetine is FDA-approved to treat the following conditions

  • Major depressive disorder (ages 8 and over)
  • Obsessive-compulsive disorder
  • Panic disorder
  • Bulimia
  • Binge eating disorder
  • Premenstrual dysphoric disorder
  • Bipolar depression
  • Treatment-resistant depression (combined with olanzapine)

Your doctor may also prescribe fluoxetine to treat other mental health conditions. 

What Does Fluoxetine Do to Your Mood?

Fluoxetine is part of a class of medications called selective serotonin reuptake inhibitors (SSRIs), which increase serotonin levels in the brain. People with depression and anxiety appear to have low concentrations of serotonin.

Serotonin is a naturally occurring chemical that helps regulate mood and emotion. As a neurotransmitter, this substance carries messages between nerve cells before being reabsorbed by the cells. SSRIs prevent this reabsorption — or reuptake — instead, making more serotonin available in the brain. This increased serotonin helps improve mood, sleep, energy and appetite and eases symptoms such as anxiety, fear and intrusive thoughts. 

What Are Common Side Effects of Fluoxetine?

Fluoxetine is available as an oral capsule, tablet or solution and is typically taken once a day. Follow the dosage instructions carefully. Your doctor may prescribe a low dosage when you start taking the medication, increasing it gradually over time. Most people see some improvement in 1 to 2 weeks, although it may take up to 4 or 5 weeks to realize a significant improvement in symptoms. 

You may experience side effects when taking fluoxetine, although in most cases, these clear up during the first few weeks of treatment. Common side effects include: 

  • Headache
  • Nausea
  • Loss of appetite
  • Diarrhea
  • Dry mouth
  • Restlessness
  • Insomnia
  • Fatigue

Be sure to see a healthcare provider if you experience unusual changes in mood or behavior, or severe side effects such as rash, hives, fever, dizziness or shortness of breath. You should also consult your doctor if the condition you're treating worsens.

Fluoxetine Coverage Under Medicare

If you have a Medicare Part D prescription drug plan or a Medicare Advantage Plan with prescription drug benefits, check your plan's formulary to see if you have coverage for fluoxetine or Prozac.  

The amount you pay for your medication depends on your plan's deductible, which is the out-of-pocket portion you're responsible for paying before your insurance plan pays its share. Once you've met your plan's deductible, you typically pay a portion of the cost of the fluoxetine, calculated as a flat fee or percentage. Your Medicare plan pays the remaining cost of the medication.

Read More
Woman gets help at pharmacy
Some of Medicare's Part D plans have been rated five stars. Learn how these ratings are determined ...
Pharmacist helps her patient in the pharmacy
Trulicity is a medication designed to help balance insulin levels in people with diabetes, and Medicare ...
A woman holds a prescription bottle while speaking with her pharmacist
Trelegy-Ellipta is a medication that's prescribed to help treat asthma and COPD symptoms. Find out ...