From the Guidelines
Fluoxetine is generally considered weight neutral, with some studies suggesting it may lead to weight loss in the short term and weight neutrality in the long term. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine and sertraline have been associated with weight loss with short-term use and weight neutrality with long-term use 1. Unlike some antidepressants that commonly cause weight gain (such as mirtazapine or paroxetine), fluoxetine typically does not lead to significant weight changes in most patients.
Key Points to Consider
- Fluoxetine's weight neutrality is one reason it's often preferred for patients concerned about medication-related weight changes.
- The weight impact of fluoxetine can vary among individuals, with some experiencing weight loss and others experiencing no significant change.
- Regular monitoring of weight changes during treatment is recommended, and lifestyle factors such as diet and exercise remain important considerations while taking this medication.
- As with any medication, the decision to prescribe fluoxetine should be based on the individual patient's needs and medical history, taking into account the potential benefits and risks of treatment 1.
Clinical Implications
The weight neutrality of fluoxetine makes it a suitable option for patients who are concerned about weight gain associated with antidepressant use. However, it is essential to consider individual responses to the medication and monitor weight changes regularly. By choosing fluoxetine for patients who are at risk of weight gain or who have concerns about weight, clinicians can help minimize the potential for medication-related weight changes while still providing effective treatment for depression. According to the study published in Gastroenterology 1, fluoxetine is a weight-neutral option, making it a valuable choice for patients with weight concerns.
From the FDA Drug Label
Altered Appetite and Weight — Significant weight loss, especially in underweight depressed or bulimic patients may be an undesirable result of treatment with Prozac. In US placebo–controlled clinical trials for major depressive disorder, 11% of patients treated with Prozac and 2% of patients treated with placebo reported anorexia (decreased appetite). Weight loss was reported in 1. 4% of patients treated with Prozac and in 0. 5% of patients treated with placebo. In US placebo–controlled clinical trials for OCD, 17% of patients treated with Prozac and 10% of patients treated with placebo reported anorexia (decreased appetite) In US placebo–controlled clinical trials for bulimia nervosa, 8% of patients treated with Prozac 60 mg and 4% of patients treated with placebo reported anorexia (decreased appetite). Patients treated with Prozac 60 mg on average lost 0.45 kg compared with a gain of 0. 16 kg by patients treated with placebo in the 16–week double–blind trial.
Fluoxetine is not weight neutral. It may cause weight loss, especially in underweight patients. The incidence of weight loss was higher in patients treated with fluoxetine compared to placebo in clinical trials for major depressive disorder, OCD, and bulimia nervosa 2.
From the Research
Weight Change Associated with Fluoxetine
- Fluoxetine may reduce weight by -2.7 kg (95% CI -4 to -1.4; p < 0.001) and body mass index by -1.1 kg/m2 (95% CI -3.7 to 1.4), compared with placebo 3.
- Some weight loss occurs with fluoxetine, although the effect appears to be limited to the acute phase of treatment 4.
- Fluoxetine is associated with weight loss, in contrast to other antidepressants that may cause weight gain 5, 6.
Comparison with Other Antidepressants
- Fluoxetine appears to have a similar effectiveness to other antidepressants, such as bupropion, amitriptyline, fluvoxamine, venlafaxine, and trazodone, in long-term treatment of major depressive disorder 7.
- Bupropion and fluvoxamine appear less effective in long-term treatment of MDD, while fluoxetine is more effective than fluvoxamine but not significantly different from bupropion 7.
Adverse Events
- Fluoxetine may cause approximately twice as many adverse events, such as dizziness, drowsiness, fatigue, insomnia, or nausea, compared with placebo 3.
- The benefit-risk ratio of fluoxetine for weight loss is unclear, and high-certainty research is needed to determine its effects exclusively and in combination with other agents 3.