Off-label fluoxetine may help overweight and obese people to lose weight, but the evidence supporting this is limited, the authors of a Cochrane review (15 October 2019) have concluded
The review and meta-analysis included 19 studies involving 2,216 participants who were randomly assigned to the serotonin reuptake inhibitor, fluoxetine or a control group. The control groups included placebo, other anti-obesity agents, omega-3 gel or no treatment.
Overall, the authors found that, compared with placebo, fluoxetine was associated with greater average weight loss, with a mean difference across all dosages and duration of treatments of –2.7kg. In studies with non-placebo control groups, the results were inconclusive.
The researchers also noted that a greater proportion of fluoxetine-treated patients experienced adverse events compared with placebo-treated patients (63.6% vs. 56.2%).
Fluoxetine is thought to influence weight by diminishing appetite and normalising altered eating behaviours, the researchers explained. They said their findings were based on low-certainty evidence, however, and that further research was needed.
“To ensure the efficacy and safety of fluoxetine in overweight or obese adults, high-certainty evidence is needed to analyse the effects of long-term use of fluoxetine to promote weight loss and to determine the severity of adverse events,” they added.