What are the side effects of Strattera (atomoxetine)?

Side Effects of Strattera (Atomoxetine)

Strattera (atomoxetine) has common side effects including gastrointestinal symptoms, fatigue, and mood changes, with rare but serious risks including suicidal ideation, liver injury, and cardiovascular effects that require monitoring. 1

Common Side Effects in Children and Adolescents

Atomoxetine is associated with several common side effects that occur in at least 2% of patients and at higher rates than placebo:

• Gastrointestinal effects:

  • Abdominal pain (17-18% vs 7-13% placebo) 1
  • Vomiting (11-14% vs 8-4% placebo) 1
  • Nausea (7-13% vs 6-4% placebo) 1
  • Constipation (2% vs 1% placebo) 1
  • Decreased appetite (16% vs 3% placebo) 1

• Neurological/psychiatric effects:

  • Fatigue (6-9% vs 4-2% placebo) 1
  • Mood swings (2% vs 0-1% placebo) 1
  • Somnolence/sedation (8-5% vs 3-1% placebo) 1
  • Dizziness (8% vs 3% placebo) 1

Common Side Effects in Adults

Adults taking atomoxetine commonly experience:

• Dry mouth (20-35% in poor metabolizers) 1
• Insomnia (15-19% in poor metabolizers) 1
• Constipation (7-11% in poor metabolizers) 1
• Decreased appetite (15-23% in poor metabolizers) 1
• Urinary hesitation/retention (6% vs 1% placebo) 1
• Sexual dysfunction (erectile dysfunction: 8% vs 1% placebo) 1
• Hyperhidrosis (4-15% vs 1-7% placebo) 1

Serious Adverse Effects

Cardiovascular Effects

• Increased heart rate and blood pressure (statistically but not usually clinically significant) 2
• Palpitations (0.4% leading to discontinuation) 1
• Chest pain (0.6% leading to discontinuation) 1

Psychiatric Effects

• Black box warning for suicidal ideation in children and adolescents 1
• Irritability (5% vs 3% placebo) 1
• Anxiety (0.4% leading to discontinuation) 1

Hepatic Effects

• Rare but serious liver injury (jaundice, elevated liver enzymes) 1, 2
• Three cases of serious liver injury deemed probably related to atomoxetine in postmarketing data 2

Neurological Effects

• Seizures (rare but reported, 0.1% of adult patients) 1, 3
• Tremor (5% in poor metabolizers vs 1% in extensive metabolizers) 1

Special Populations and Considerations

Metabolizer Status

Side effect profiles differ based on CYP2D6 metabolizer status:

• Poor metabolizers (approximately 7% of population) experience:
  • Higher drug concentrations (approximately 10-fold higher) 4
  • More frequent adverse effects 1
  • Longer half-life (21.6 hours vs 5.2 hours in extensive metabolizers) 4

Pregnancy and Breastfeeding

• Limited data on use during pregnancy 5
• Possible increased risk for spontaneous abortion, though confounding factors may exist 5
• No evidence of increased risk for major congenital malformations 5
• Caution advised during breastfeeding - likely present in breast milk due to low molecular weight and long half-life 5

Monitoring Recommendations

• Vital signs: Regular monitoring of heart rate and blood pressure 6
• Growth parameters: Height and weight should be monitored regularly in children 6
• Liver function: Consider monitoring liver enzymes, especially with symptoms of liver dysfunction 1
• Mental health: Monitor for emergence of suicidal thoughts or behaviors 1

Risk Mitigation

• Start at lower doses and titrate gradually (typically starting at 40mg daily) 6
• Consider lower doses in poor metabolizers 1
• Avoid abrupt discontinuation to prevent discontinuation symptoms 1
• Use caution when combining with medications that inhibit CYP2D6 4
• Contraindicated with MAOIs due to risk of serotonin syndrome 1

Atomoxetine has a different side effect profile compared to stimulants, with notably less insomnia but more somnolence, making it potentially beneficial for patients who experience sleep disturbances with stimulants 2.