Weight Gain with Quetiapine SR 100 mg
Expect approximately 1.4-5.6 kg of weight gain over 6-12 months with quetiapine sustained-release 100 mg, with most weight gain (>60%) occurring within the first 12 weeks of treatment. 1, 2, 3
Weight Gain Range and Timeline
Based on FDA drug labeling data and clinical trials, quetiapine causes dose-dependent weight gain that follows a predictable pattern:
Short-Term (First 3 Months)
- Most rapid weight gain occurs in weeks 1-12, accounting for over 60% of total weight gain 3
- At low doses (<200 mg/day), mean weight gain is 1.54 kg over initial treatment period 3
- One study of 100 mg or less showed 0.49 kg at 1 month (not statistically significant) 2
Medium-Term (6 Months)
- 5.56 kg mean weight gain at 6 months with doses ≤100 mg (statistically significant, p<0.001) 2
- Weight gain continues but at a slower rate after the initial 12 weeks 3
Long-Term (12 Months)
- 10.58 kg mean weight gain at 12 months with doses ≤100 mg (p<0.001) 2
- For all quetiapine doses at 52 weeks: mean 3.19 kg, median 2.5 kg 3
- 37% of patients gain ≥7% of baseline body weight at 1 year 3
Clinical Context from Guidelines
The 2015 Endocrine Society guidelines specifically identify quetiapine as an antipsychotic associated with significant weight gain 4. In comparative trials, 16% of quetiapine-treated patients experienced >7% weight gain versus 7% with ziprasidone 4. The guidelines recommend using weight-neutral antipsychotic alternatives when clinically indicated and employing shared decision-making with patients about expected weight effects 4.
More recent 2017 guidelines confirm that olanzapine, clozapine, quetiapine, and risperidone are consistently associated with weight gain 5.
Important Caveats
Even low doses cause metabolic effects: A 2025 meta-analysis confirmed that quetiapine <200 mg causes significant weight gain (mean difference 0.58 kg) and HDL cholesterol reduction, with patients 2.12 times more likely to gain ≥7% of baseline weight 6. This contradicts the common clinical assumption that low doses are metabolically benign.
Dose relationship is complex: While there is a general dose-response relationship, the pattern is not strictly linear. Doses 200-399 mg/day showed the highest weight gain (4.08 kg), while 400-599 mg/day showed less (1.89 kg) 3. At 100 mg, you're in the lower range but still expect clinically significant weight gain.
Individual variation is substantial: Weight gain inversely correlates with baseline BMI—patients with lower baseline BMI tend to gain more weight 3. Age and sex also matter: elderly patients and men show greater dose-related weight gain 7.
Monitoring Recommendations
Regular weight monitoring is essential per FDA labeling 1. Given that most weight gain occurs in the first 12 weeks, weekly to biweekly weights during the first 3 months are critical for early intervention. After 3 months, monthly monitoring is reasonable as weight gain velocity decreases.
Consider metabolic panel monitoring as quetiapine also affects lipids (particularly triglycerides and HDL cholesterol) even at low doses 6, 8.