What to Know about Fluoxetine (Prozac)

One common medication often used to treat depression is fluoxetine (often known by the brand names Prozac or Sarafem). For people with depression, taking medication is a significant step in allowing them to improve their mental health.

On this page, we’ve outlined some important information about the drug.

What is fluoxetine (Prozac)?

What is fluoxetine? How does it work?

Fluoxetine is an antidepressant approved to treat conditions such as depression, Obsessive-Compulsive Disorder (OCD), eating disorders, panic attacks. It may sometimes be used off-label to treat alcoholism, phobias, attention deficit disorder, borderline personality disorder, headaches, PTSD, bulimia nervosa, and more. 

Fluoxetine belongs to a class of medications called selective serotonin reuptake inhibitors (SSRIS). Medications in this class produce their effect by preventing the reabsorption of a certain chemical in the brain called serotonin, thus keeping serotonin levels high. Serotonin helps improve mood and maintain mental balance. 

How is fluoxetine typically used?

Many adults with depression are prescribed to take a 10 or 20mg pill orally once daily. For those who do not respond to this amount, doctors often increase the dosage to two 20mg pills daily, for a total of 40 mg in one day. Prescribed dosages differ depending on who is being prescribed and what the medication is being prescribed for. 

Sometimes, doctors will start their patients off on a lower prescription and increase it over time to help avoid any negative reactions. A liquid is also available for doses smaller than 10 mg. Only take your medication as prescribed by a health professional. Don’t worry if fluoxetine doesn’t make you feel better immediately, as it can take several weeks for the full effects to show. Because it is relatively stimulating, it is typically taken in the morning to avoid negative effects on sleep.

You should not stop taking fluoxetine without first informing your doctor. Stopping the medication abruptly can cause negative effects in your body. If you need to stop taking fluoxetine, your doctor would reduce your dose over time till it’s safe to stop. This process is called tapering the dose, and it helps avoid negative reactions associated with coming off of an SSRI too quickly. 

What are some possible side effects?

Some common side effects of fluoxetine include:

  • Nervousness
  • Difficulty falling asleep 
  • Diarrhea
  • Heartburn
  • Muscle tremor

Some serious (but uncommon side effects) include:

  • Blisters
  • Rash
  • Difficulty breathing or swallowing
  • Itching
  • Fever
  • Joint pain

Call 911 or seek emergency care if you notice any severe side effects. You can learn more about common and uncommon side effects of fluoxetine here

Why do these side effects occur? 

Any medication can potentially lead to side effects, and a person’s likelihood of having side effects depends on many factors, including age, lifestyle, and the type of medication itself. Side effects may occur because drugs often have broad or poorly targeted effects, or the drug target itself may have many downstream effects on the body. 

Apart from a person’s mood, serotonin is also involved in regulating some other activities of the body like sleeping, eating, digestion etc. Increasing the level of serotonin in the brain can sometimes affect these other activities, causing unexpected side effects. 

Many non-serious side effects of mental health medications like fluoxetine go away after a few weeks as your body gets used to the medication. However, if a side effect persists, is intolerable, or severely hinders your ability to go about your daily life, talk to your doctor, because this might be a sign that the medication is not a good fit. 

How do your genes relate to fluoxetine? 

Genetics can affect your body’s response to medication. Some people with a certain variation of CYP2D6 gene might not be able to use certain other medications alongside fluoxetine. The CYP2D6 gene is responsible for breaking many medications, and fluoxetine can inhibit this breakdown. This means that when taking fluoxetine, the pathway cannot break down other drugs normally, leading to these drugs staying longer in the body and causing unintended side effects. Your doctor may need to adjust your medication regimen or prescribe a different mental health medication to avoid these interactions. 

One way to predict whether you’ll have a positive outcome while taking fluoxetine is by taking a genetic test to determine what genetic variations you have and how they affect medication metabolization. Your DNA can help your doctor rule out less suitable medications and make more informed decisions so that you can get better, faster.

Special Precautions

  • Taking fluoxetine together with certain medication can lead to severe complications. Notify your doctor of any other medication you might be taking alongside fluoxetine to be sure of its safety. 
  • Inform your doctor if you have a high risk of bleeding or are taking medication that can increase this risk e.g. aspirin before you start taking fluoxetine. 
  • Teenagers and young adults may notice changes in their behavior when taking fluoxetine. It is important to notify your doctor of these changes to know whether you need any dose adjustment. 
  • Notify your doctor if you start to experience blurry vision or any other trouble with your eyes when taking fluoxetine. 
  • Your doctor should be adequately informed if you have any heart, liver, kidney conditions before you start taking fluoxetine to ensure proper dose adjustment is carried out. 

If you show signs of an allergic reaction to fluoxetine (hives, difficulty breathing, rash, swelling), call 911 or go to the nearest emergency department.

Some medications, vitamins, and herbs may interfere with how fluoxetine works. Make sure to tell your doctor about all other medications you are taking before starting fluoxetine to avoid negative interactions. For full details, see the FDA’s full list of precautions

Looking to find the right medication for your mental health? Join Prairie today to connect to expert providers and affordable medication options. 

Authors

  • Dr. Mike Hoaglin is a practicing mental health physician, advisor, and digital health expert passionate about clinical transformation and the microbiome. Dr. Hoaglin earned his medical degree from the Perelman School of Medicine at the University of Pennsylvania, with residency training at The Brooklyn Hospital Center and Duke University Medical Center.

  • Prairie Health is an online psychiatry service focused on reducing all barriers to mental healthcare and modernizing treatment. Prairie specializes in helping adults with depression or anxiety get better through online psychiatry appointments, genetics-informed medication plans and ongoing support, all from the comfort of home.

Published
Categorized as Medication

By Mike Hoaglin

Dr. Mike Hoaglin is a practicing mental health physician, advisor, and digital health expert passionate about clinical transformation and the microbiome. Dr. Hoaglin earned his medical degree from the Perelman School of Medicine at the University of Pennsylvania, with residency training at The Brooklyn Hospital Center and Duke University Medical Center.