What Is the Connection between Fluoxetine and Weight Gain?

Tricia Christensen
Tricia Christensen
Tricia Christensen
Tricia Christensen
Many antidepressants are associated with weight gain.
Many antidepressants are associated with weight gain.

In roughly 1 percent of users, fluoxetine, an antidepressant principally used in the treatment of depressive and anxiety disorders, is thought to cause weight gain. The matter is more complex when the numerous clinical findings about fluoxetine and weight gain are considered. For example, there are a number of studies connecting the drug to weight loss. Additionally, it is often thought that weight gain or loss is more related to behaviors associated with the conditions the drug treats and recovery from them.

Fluoxetine is an antidepressant that acts on serotonin receptors in the brain.
Fluoxetine is an antidepressant that acts on serotonin receptors in the brain.

Many antidepressants are associated with weight gain. The ones most like to cause increased weight do not usually belong to the selective serotonin reuptake inhibitor (SSRI) class, of which fluoxetine is a member. One exception is the drug, paroxetine, which is an SSRI. Most of the other antidepressants known for weight gain are older types such as amitriptyline, mirtazapine, and trazodone. Even with these medications, gaining weight is a possible adverse effect, but it isn't assured, and some patients will use them without weight troubles.

Fluoxetine capsules can be used to treat panic disorders in adults.
Fluoxetine capsules can be used to treat panic disorders in adults.

Sometimes individuals are worried about fluoxetine and weight gain because they think of all antidepressants as causing elevated weight in a high number of users. This perception is incorrect, and it's harmful. Fear of gaining weight should not stop people from treating depression or anxiety disorders.

Serotonin is also thought to inhibit appetite and SSRIs may be beneficial in this respect. Certainly, for some people fluoxetine and weight gain aren't connected at all, and the drug may cause weight loss. It has even been prescribed in higher amounts with antipsychotic medications that are typically associated with pronounced increases in weight. This has been done to prevent weight gain, and studies have found it effective.

Selective serotonin re-uptake inhibitors (SSRIs) are prescribed as antidepressants in the treatment of depression and anxiety disorders.
Selective serotonin re-uptake inhibitors (SSRIs) are prescribed as antidepressants in the treatment of depression and anxiety disorders.

One explanation for the fluoxetine and weight gain correlation has to do with the conditions the drug treats. A potential symptom of depression is sudden, unexplained weight loss, and many anxiety disorders suppress appetite. Fluoxetine may improve these conditions and return people to a normal appetite. This can cause slight gain in weight. This gain ordinarily doesn't significantly elevate measurements of body mass index (BMI), and is usually not concerning in a patient with a healthy starting BMI.

Serotonin is thought to inhibit appetite, and SSRIs may be beneficial in this respect.
Serotonin is thought to inhibit appetite, and SSRIs may be beneficial in this respect.

Depression may also result in lack of energy to exercise. These patterns may persist with recovery. Alternately, fluoxetine, which isn't always effective, may not alleviate depression and poor eating and exercise habits could remain unaddressed. If patients are relatively inactive and they eat high sugar and high fat foods, the likelihood of gaining weight on fluoxetine is higher. Depression and anxiety can also cause insomnia, which has been correlated to larger waistlines and unhealthy BMI measurements.

The best advice for someone worried about fluoxetine and weight gain is to discuss this matter with a physician. The majority of people taking this drug will not experience this side effect. Still, if the drug is prescribed, it is important to commit to a healthy diet and regular exercise, as this may help prevent weight increases.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

Tricia Christensen
Tricia Christensen

Tricia has a Literature degree from Sonoma State University and has been a frequent wiseGEEK contributor for many years. She is especially passionate about reading and writing, although her other interests include medicine, art, film, history, politics, ethics, and religion. Tricia lives in Northern California and is currently working on her first novel.

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    • Many antidepressants are associated with weight gain.
      Many antidepressants are associated with weight gain.
    • Fluoxetine is an antidepressant that acts on serotonin receptors in the brain.
      Fluoxetine is an antidepressant that acts on serotonin receptors in the brain.
    • Fluoxetine capsules can be used to treat panic disorders in adults.
      Fluoxetine capsules can be used to treat panic disorders in adults.
    • Selective serotonin re-uptake inhibitors (SSRIs) are prescribed as antidepressants in the treatment of depression and anxiety disorders.
      Selective serotonin re-uptake inhibitors (SSRIs) are prescribed as antidepressants in the treatment of depression and anxiety disorders.
    • Serotonin is thought to inhibit appetite, and SSRIs may be beneficial in this respect.
      Serotonin is thought to inhibit appetite, and SSRIs may be beneficial in this respect.