From the FDA Drug Label
In the pediatric MDD and GAD, trials up to 36 weeks long, there were 822 duloxetine delayed-release capsules-treated pediatric patients aged 7 to 17 years of age (most patients received 30 to 120 mg per day) – 42% were 7 to 11 years of age (58% were 12 to 17 years old) and 52% were female Most Common Adverse Reactions in Pediatric Trials The most common adverse reactions (≥5% in duloxetine delayed-release capsules-treated patients and at least twice the incidence of placebo-treated patients) in all pooled pediatric populations (MDD, GAD, and another indication) were decreased weight, decreased appetite, nausea, vomiting, fatigue, and diarrhea Decreased appetite and weight loss have been observed in association with the use of SSRIs and SNRIs. Duloxetine delayed-release capsules-treated pediatric patients in clinical trials experienced a 0.1 kg mean decrease in weight at 10 weeks, compared with a mean weight gain of approximately 0. 9 kg in placebo-treated pediatric patients. The proportion of patients who experienced a clinically significant decrease in weight (≥3. 5%) was greater in the duloxetine delayed-release capsules group than in the placebo group (16% and 6%, respectively).
Duloxetine and Weight Gain:
- Duloxetine is not typically associated with weight gain.
- In pediatric patients, duloxetine has been linked to decreased weight and decreased appetite.
- Studies have shown that duloxetine-treated pediatric patients experienced a mean decrease in weight, compared to a mean weight gain in placebo-treated patients 1.
- The proportion of patients with a clinically significant decrease in weight was higher in the duloxetine group than in the placebo group 1.
- There is no direct evidence to suggest that duloxetine causes weight gain; instead, the evidence suggests that it may lead to weight loss, particularly in pediatric patients 1, 1.
From the Research
Duloxetine (Cymbalta) can cause weight gain in some patients, as evidenced by a recent study published in 2024 2. This study, which compared weight change across common first-line antidepressant treatments, found that duloxetine was associated with a higher estimated 6-month weight gain compared to sertraline, with a difference of 0.34 kg. The study also found that duloxetine was associated with a 10% to 15% higher risk for gaining at least 5% of baseline weight. Other studies have also reported weight gain with duloxetine use, including a 2021 study that found a mean weight gain of 5.5 lb in patients taking duloxetine and pregabalin combination therapy after 12 to 18 months of treatment 3. However, the weight changes are typically modest, often less than 5 pounds for most people. The mechanism behind this side effect likely involves duloxetine's impact on serotonin and norepinephrine levels, which can affect appetite regulation and metabolism. Weight gain tends to be more common with longer-term use, typically after several months of treatment. If you're concerned about weight gain while taking duloxetine, maintaining regular physical activity and a balanced diet may help minimize this side effect. It's essential to discuss any significant weight changes with your healthcare provider, who can evaluate if medication adjustments are needed or if the benefits of continuing duloxetine outweigh this side effect. Some key points to consider when taking duloxetine include:
- Monitoring weight changes regularly
- Maintaining a healthy diet and exercise routine
- Discussing any concerns about weight gain with your healthcare provider
- Avoiding abrupt discontinuation of duloxetine due to weight concerns, as this can cause withdrawal symptoms. Overall, while duloxetine can cause weight gain in some patients, the benefits of the medication often outweigh this side effect, and healthcare providers can work with patients to minimize weight gain and maximize the benefits of treatment.