Can Strattera (Atomoxetine) Cause Increased Anxiety?
Yes, atomoxetine can cause increased anxiety as an adverse effect, but clinical trial data demonstrates it does not worsen anxiety in patients with ADHD and comorbid anxiety disorders. 1
Key Evidence from FDA Labeling
The FDA label explicitly addresses this concern through two well-designed trials:
In pediatric patients (ages 8-17): A 12-week placebo-controlled trial of 176 patients with ADHD and comorbid anxiety disorders (separation anxiety, generalized anxiety, or social phobia) demonstrated that atomoxetine did not worsen anxiety as measured by the Pediatric Anxiety Rating Scale (PARS), despite anxiety being listed as a potential adverse effect. 1
In adults (ages 18-65): A 16-week trial of 442 patients with ADHD and social anxiety disorder showed atomoxetine did not worsen anxiety as measured by the Liebowitz Social Anxiety Scale (LSAS). 1
However, the FDA label acknowledges postmarketing reports of anxiety as an adverse event, indicating this can occur in real-world practice. 1
Clinical Context and Mechanism
Atomoxetine's noradrenergic mechanism theoretically could increase anxiety, as it enhances norepinephrine transmission—a neurotransmitter associated with the stress response and "fight or flight" reactions. 2 Despite this theoretical concern, the paradoxical effectiveness of noradrenergic medications in anxiety disorders likely relates to complex interactions with other neurotransmitters including serotonin. 2
Adverse Event Profile
Common adverse effects of atomoxetine include: 3, 1
- Nausea and vomiting
- Fatigue and somnolence
- Decreased appetite
- Abdominal pain
- Anxiety (postmarketing reports)
Critical monitoring requirement: All children treated with atomoxetine must be monitored closely for suicidality, clinical worsening, and unusual behavioral changes, especially during the first few months or with dose adjustments. 3 The FDA meta-analysis showed increased suicidal ideation risk in pediatric patients compared to placebo. 3, 4
Practical Clinical Approach
For patients with pre-existing anxiety:
- Atomoxetine is specifically useful for ADHD patients with comorbid anxiety or tics, as it does not exacerbate these conditions in controlled trials. 4, 5
- Start with lower doses and titrate slowly to minimize early adverse effects. 3
- Monitor anxiety symptoms systematically using validated scales during the first 6-8 weeks of treatment. 6
For patients without anxiety history:
- Be aware that anxiety can emerge as a new adverse effect in some patients (postmarketing data). 1
- Educate patients and families about this potential side effect before initiating treatment. 1
Comparison to Stimulants
Atomoxetine has distinct advantages over stimulants for anxiety-prone patients, as it carries negligible abuse potential, is not a controlled substance, and provides extended symptom control throughout the day and evening without the rebound effects sometimes seen with stimulants. 4, 5 The adverse event profile differs from stimulants, with somnolence more common with atomoxetine versus insomnia more common with stimulants. 4
Common Pitfall to Avoid
Do not assume anxiety worsening is inevitable. The controlled trial data is reassuring that atomoxetine does not systematically worsen anxiety in patients with comorbid anxiety disorders, despite theoretical concerns and occasional postmarketing reports. 1 If anxiety emerges or worsens, consider dose reduction, slower titration, or alternative ADHD treatments rather than immediately discontinuing. 6