Does Taking Prozac Cause Weight Gain?

Published March 11th, 2021 by Erik Rivera
Fact Checked by
Camille Freking
Medically Reviewed:
Dr. Gerardo Sison
Updated Date: Mar 19th, 2022

Many people who suffer from mental health conditions like depression and panic disorder are interested in pursuing prescription medication treatment, but weight gain is a common concern. 

Prozac is perhaps the most well-known antidepressant on the market, and while its safety and effectiveness are well documented, the drug is also associated with a long list of side effects.  

Does taking Prozac cause weight gain, and how does the drug compare to other medications in its class in terms of side effects?

What is Prozac?

Prozac is a brand-name prescription medication that belongs to a class of drugs called selective serotonin reuptake inhibitors (SSRIs).

FDA-approved in 1987, Prozac was the first SSRI antidepressant medication, which revolutionized the treatment of depression and other common mental health conditions. 

Today, SSRIs are one of the most popularly prescribed classes of drugs in the United States due to the prevalence of depression and anxiety and the effectiveness of this class of drugs as a treatment option. 

Other SSRIs include citalopram (Celexa), escitalopram (Lexapro), sertraline (Zoloft), and paroxetine (Paxil). 

Approximately 22 million prescriptions were written for Prozac in 2017, making it the most well-known and one of the most popular SSRIs on the market. Prozac is also sold under the generic name fluoxetine.

What is Prozac used to treat?

Prozac was first approved by the FDA in 1987 for the treatment of major depressive disorder, otherwise known as clinical depression. 

Since that time the FDA has approved Prozac for the treatment of a number of other common mental health conditions, including obsessive-compulsive disorder (OCD), panic disorder, and bulimia nervosa.

It is also marketed under a different name, Sarafem, to treat premenstrual dysphoric disorder (PMDD). 

Depending on the condition being treated, Prozac can be used safely in both children and adults.

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Does taking Prozac cause weight gain?

While most antidepressants have a reputation for causing weight gain, Prozac does not typically cause weight gain. 

Numerous studies have been conducted to determine the effect of antidepressant use on weight.

These studies have found that mild to significant weight gain is a common side effect of atypical antipsychotics and many newer antidepressant drugs except Prozac, which was associated with moderate weight loss when used for the acute treatment of depression.

These newer antidepressants include tricyclic antidepressants (TCAs) such as amitriptyline (Elavil); monoamine oxidase inhibitors MAOIs including phenelzine (Nardil); and SNRIs like duloxetine (Cymbalta) and venlafaxine (Effexor). 

Other studies have shown that acute treatment with Prozac is likely to cause weight loss, while long-term treatment with the drug may lead to some degree of weight gain.

However, the extra pounds may be attributed to improvement in depression symptoms rather than the medication itself. 

Prozac is considered to be a weight-neutral antidepressant, so it may be a good treatment option for patients who are concerned about body weight change.

What side effects are associated with Prozac?

Prozac is associated with side effects that can be categorized as both common and rare/serious. 

Common side effects associated with Prozac include:

  • Headache

  • Nausea

  • Flu-like symptoms

  • Increased sweating

  • Nervousness

  • Diarrhea

  • Dry mouth 

  • Increased bruising or minor skin rashes

  • Difficulty sleeping (insomnia)

  • Decreased libido or sex drive

  • Weight loss

  • Drowsiness and tiredness

  • Sexual dysfunction, such as difficulty with orgasm or ejaculatory delay

Rare but serious side effects associated with Prozac include:

  • Low sodium blood levels, which can cause symptoms such as:

    • Headache

    • Confusion

    • Weakness

    • Difficulty concentrating

  • Seizures

  • Suicidal thoughts or behaviors

  • Visual problems such as:

    • Changes in vision

    • Eye pain

    • Swelling or redness in or around the eye

  • Serotonin syndrome, which can cause symptoms such as:

    • Tremors

    • Severe muscular tightness

    • Fever

    • Diarrhea

    • Confusion

    • Seizures

    • Agitation

  • QT prolongation and ventricular arrhythmia, or changes in the electrical activity of your heart

This may not be a complete list of side effects. Consult a healthcare provider for other possible side effects associated with Prozac. 


Prozac is one of the few antidepressants that is not associated with weight gain and is considered a weight-neutral medication. Many people taking Prozac for acute treatment end up losing weight while taking the drug.  

When taken for an extended period of time, patients using Prozac were found to gain an amount of weight that was comparable to weight gain in study participants who received a placebo. 

Therefore, it is likely that this weight gain is due to recovery from depression rather than the medication itself. This weight gain can be mitigated by wellness practices such as regular physical activity, nutritional supplements, and changes in diet overseen by a nutritionist. 

Seek medical advice from your prescribing doctor to see if Prozac is right for you. Patients who have been prescribed Prozac can save money on the generic or brand name forms of the medication using a pharmacy discount card from USA Rx.


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