Disclaimer: None of the information in this article constitutes medical advice, and is just the opinion of the writer(s) and published for informational purposes only. We recommend that patients follow their doctor’s guidance in regard to prescription medication.
Fluoxetine is a popular antidepressant that has been on the market since 1999. It’s the generic version of the drug Prozac, and as we outlined in our Prozac reviews article, both drugs contain the exact same active ingredient, so we can describe them interchangeably.
In this article we’ll examine medical studies on fluoxetine to determine if it’s safe and effective for treating depression, obsessive-compulsive disorder (OCD), panic disorder and other uses that it’s approved by the Food and Drug Administration (FDA) in the U.S. to treat.
Does Fluoxetine Work?
Fluoxetine has been involved in numerous medical trials testing its efficacy for treating a wide range of mental health complaints. This medication is most commonly prescribed for depression, and the majority of medical studies we reviewed on this drug were for its antidepressant effect
Fluoxetine was FDA-approved several decades ago, so most of the studies involving the drug aren’t recent. A medical review published in the Annals of General Hospital Psychiatry journal examined the results from 87 individual clinical trials on fluoxetine for depression, with data on 9,087 patients.
What the study authors found was that fluoxetine was effective for treating depression from the very first week of therapy. The medication decreased average patient depression scores to a statistically significant degree.
A clinical trial published in 2017 examined how living environment could impact the effectiveness of fluoxetine. Mice which received the drug in a supportive living environment had a reduction of their symptoms, while mice that received the drug in a stressful living environment had a worsening of their symptoms.
This trial failed to clearly define how the living environment was made to be “enriched” or “stressful,” but the results suggest that fluoxetine may be more effective in patients with a supportive and loving home environment. We would imagine this would be the case for most antidepressants.
Fluoxetine is also proven to be effective for treating Obsessive Compulsive Disorder (OCD), which is increasing in the U.S. The linked study analyzed the effects of the medication on 265 OCD patients, and found that its use “significantly decreased” their symptoms.
The drug was found to be most beneficial to a subcategory of OCD patients termed “washers” (patients with a phobia of germs who excessively wash their hands), and less beneficial to a subcategory called “checkers” (patients who have to check through a list of items before completing their daily routines).
As referenced in the intro section, fluoxetine is also approved for treatment of panic disorder, and it appears to be effective for that use case based on medical research. A clinical trial published in the well-respected Journal of Clinical Psychopharmacology examined the effects of the drug on 25 patients with diagnosed panic disorder.
76% of the patients experienced a significant improvement in their symptoms. This was a small trial, and not especially well-designed in our opinion, but these results are still meaningful, especially considering that panic disorder can be difficult to treat.
Fluoxetine is also approved for treatment of bulimia. A medical study published in 1992 compared the efficacy of the drug against a placebo on 387 bulimic patients. Those using fluoxetine experienced decreased frequencies of binge eating and vomiting episodes, and the 60 milligram (mg) per day dosage was found to be more effective for this patient population than the 20 mg per day dosage.
There were secondary benefits in the bulimic patients, such as improvements in depression, carbohydrate craving and pathologic eating attitudes.
We can conclude from the available research that fluoxetine is effective for treating a wide range of mental health conditions. There is more research backing its effectiveness for treating depression than for other conditions, as the medication was initially approved for depression.
How Does Fluoxetine Work?
Fluoxetine is a member of a class of pharmaceutical drugs called Selective Serotonin Reuptake Inhibitors (SSRI). This is the most commonly-prescribed class of drugs for depression.
As we documented in our Celexa reviews article, which covered another popular SSRI med, this class of drugs minimizes the reuptake of serotonin in the brain. This artificially increases circulating serotonin levels. Serotonin is a neurotransmitter that influences mood and depression, so by increasing its levels it may normalize brain function in patients
Researchers still haven’t conclusively shown that low levels of serotonin in the brain are the cause of depression; we just know that this type of drug is effective on average for depressed patients.
In the near future, we believe that pharmaceutical depression treatment will be much more individualized, as it seems logically clear that one single neurotransmitter isn’t the cause of depression for all patients.
Fluoxetine Side Effects
SSRI drugs do cause side effects in some patients, and fluoxetine is no exception.
A meta-study of the side effects of this medication found that the most common side effects were nausea, nervousness and insomnia. The study authors found that these side effects were actually more common in patients taking fluoxetine than those taking a different class of antidepressants called tricyclic antidepressants.
This suggests that patients with anxiety or insomnia disorders may wish to speak with their doctor about tricyclic antidepressants instead of fluoxetine.
Branded versions of fluoxetine such as Prozac are required by the FDA to publish a “black box” warning on their label indicating that the drug may increase risk of suicidal thoughts and behaviors. This is unfortunately common for SSRI medications.
Increased risk of suicidality will not affect most fluoxetine users; it’s a rare side effect, but definitely one worth speaking with a doctor about, especially for patients with a family history of suicidality.
Every patient requires an individualized dosage strategy that should be discussed with a doctor, but we can review the medical research on typical dosage of fluoxetine for treating depression.
StatPearls, which is one of the largest free medical databases and is maintained by the National Institutes of Health (NIH) in the U.S., indicates on their resource page that fluoxetine dosage typically starts at 20 mg per day. It can be broken into smaller doses taken throughout the day to minimize side effects.
A patient prone to anxiety may start on a 10 mg dose in the morning and a 10 mg dose in the evening rather than one single 20 mg dose to decrease the risk of acute side effects.
Fluoxetine has been studied, and proven safe on average, at doses up to 80 mg daily according to StatPearls. Typically a doctor will increase the dosage up to the safety limit if the patient isn’t responding to treatment. If a patient isn’t experiencing any benefit at 80 mg per day, they should probably speak with their doctor about alternate antidepressants.
Fluoxetine and Alcohol
There’s some interesting medical research in regard to how fluoxetine can change desire to drink alcohol.
A clinical trial on an alcoholic patient population found that fluoxetine decreased the desire to drink. The trial participants were presented with a variety of alcoholic beverages, and showed a decreased desire to drink any of them compared with the placebo group. Fluoxetine at a dose of 60 mg per day decreased alcoholic drinks consumed by around 50%.
These results were mirrored in a separate clinical trial which found that depressed alcoholic patients taking fluoxetine had improvement in depression scores and also decreased their alcohol intake throughout the course of the trial.
Based on the available research it seems as though fluoxetine may be an especially effective option for patients with both depression and substance abuse issues.
We don’t recommend fluoxetine as a standalone treatment for alcoholism, because the drug is not FDA-approved for that use.
Fluoxetine Vs. Fluvoxamine
Fluvoxamine is another popular SSRI antidepressant, so patients are often curious about which drug is more safe and effective.
A medical trial published in 2003 directly compared the effectiveness of these two drugs for treating major depression. Depressed patients were given either of the two drugs for 6 weeks, and researchers tracked changes in their depression scores using the Hamilton Depression Rating Scale (HAMD), which is a way for doctors to track severity of depression.
The study authors found that there was no difference in efficacy. Both drugs decreased depression on average to a statistically significant degree. Fluvoxamine took a shorter duration of time to be effective, so it may be a better option for patients suffering from a severe, acute depressive episode.
Fluoxetine Vs. Prozac
Prozac is the branded version of fluoxetine, as we mentioned earlier in this article. This means that these two medications, while having different names, contain the exact same active chemical compound.
We would recommend that patients speak with their doctor about fluoxetine rather than Prozac. Since both drugs contain the same active ingredient, it seems logical to take the generic version which tends to be cheaper. This is an especially important consideration for patients without health insurance.
A medical review that we reference often in our articles compared the efficacy of branded and generic drugs. As would be expected, generic drugs were found to be just as effective as branded drugs.
User Reviews of Fluoxetine
One of the resources which we find useful when evaluating prescription medications is Drugs.com. This website allows users of prescription drugs to publish reviews of their experience. We cannot verify the accuracy or legitimacy of any information on this site.
Fluoxetine has an average rating of 7/10 on Drugs.com for treating depression, which is a relatively high score compared with most of the medication reviews we’ve analyzed from this website in our previous articles.
The top positive review of the drug comes from a user named “READTHISPLEASE” who claims that the drug caused a significant improvement in their mental state:
“ONE YEAR AGO I WAS YOU READING THIS COMMENTS THINKING IT WOULD NEVER GET BETTER. WELL IT GOT PRETTY DAMN BETTER. (: God bless whoever is reading this.”
The top negative review of fluoxetine is from a user called “Mc” who claims the drug caused them to gain weight:
“Caused uncontrollable massive weight gain just like the atypical antipsychotics do (129 to 185 in 3 months!!! Eating same diet. Robot emotions. Hair loss. And suddenly...good old diabetes 2.”