What is the frequency of weight gain as a side effect of guanfacine (Intuniv) therapy?

Weight Gain with Guanfacine

Weight gain is not a common side effect of guanfacine therapy, and guanfacine monotherapy has not been associated with clinically meaningful deviations from normal growth trajectories in children and adolescents with ADHD. 1

Frequency of Weight Gain with Guanfacine

According to the available evidence, guanfacine is not typically associated with weight gain as a significant side effect. In fact, a comprehensive longitudinal database study specifically examining the impact of guanfacine on weight and height in children and adolescents with ADHD found that:

• Guanfacine monotherapy (whether used as first-line or non-first-line treatment) was not associated with marked deviations from normal growth patterns 1
• This contrasts with stimulant medications, which showed initially declining growth trajectories 1

Common Side Effects of Guanfacine

The most frequently reported side effects of guanfacine include:

• Somnolence (38.6%) 2
• Headaches (20.5%) 2
• Fatigue (15.2%) 2
• Drowsiness 3
• Irritability 3
• Dry mouth 3
• Dizziness 3
• Hypotension/bradycardia 3
• Abdominal pain 3

Comparison with Other ADHD Medications

When considering weight-related side effects across ADHD medications:

1. Stimulants: Commonly cause appetite suppression and potential growth delays 3

   • The MTA study identified persistent effects on decreasing growth velocity with stimulants 3
   • Growth diminution was in the range of 1-2 cm from predicted adult height 3

2. Atomoxetine: Associated with decreased appetite and potential growth delays in the first 1-2 years of treatment 3

3. Guanfacine: Not associated with clinically meaningful weight changes when used as monotherapy 1

4. Clonidine: Similar side effect profile to guanfacine, but no specific weight gain concerns noted in guidelines 3

Clinical Implications

When prescribing guanfacine, clinicians should be aware that:

• About 80% of patients taking guanfacine will experience at least one treatment-emergent adverse event (compared to 66.5% with placebo) 2
• The most concerning side effects are cardiovascular (decreased heart rate and blood pressure) rather than weight-related 3
• Guanfacine should be tapered rather than suddenly discontinued to prevent rebound hypertension 3

Monitoring Recommendations

While weight gain is not a primary concern with guanfacine therapy, routine monitoring should include:

• Blood pressure and heart rate at baseline and periodically during treatment 3
• Height and weight measurements to track growth patterns, particularly in children and adolescents
• Assessment for somnolence and sedation, which are more common side effects 3

Conclusion

Weight gain is not considered a common or significant side effect of guanfacine therapy. The evidence suggests that guanfacine monotherapy does not cause clinically meaningful deviations from normal weight trajectories, unlike some other medications used for ADHD such as stimulants, which are more commonly associated with growth and weight concerns.