What are the potential side effects of taking Strattera (atomoxetine) 40mg twice a day (bid)?

Common Side Effects of Strattera 40 mg BID

You should expect gastrointestinal symptoms (nausea, vomiting, abdominal pain), decreased appetite, fatigue, and somnolence as the most common side effects when taking Strattera 40 mg twice daily. 1

Most Frequent Adverse Effects

The FDA-approved prescribing information identifies the following as the most commonly observed adverse reactions (occurring in ≥5% of patients and at least twice the rate of placebo):

• Nausea (10% in children/adolescents, significantly higher in adults) 1, 2
• Vomiting (11% in children/adolescents) 1
• Decreased appetite (16% in children/adolescents) 1, 2
• Abdominal pain (18% in children/adolescents) 1
• Fatigue (8% in children/adolescents) 1
• Somnolence/sedation (11% in children/adolescents) 1, 2

Gastrointestinal Effects

Gastrointestinal symptoms are the most prominent side effects and typically occur early in treatment. 2

• Abdominal pain affects approximately 18% of pediatric patients (versus 10% on placebo) 1
• Nausea and vomiting are generally mild to moderate in severity 2, 3
• These effects are often transient and may diminish with continued treatment 3
• Taking atomoxetine with food can reduce gastrointestinal side effects 1

Appetite and Weight Effects

• Decreased appetite occurs in 16% of patients 1
• Initial weight loss may occur, but long-term studies show weight and height gain typically return to normal trajectories 2, 3
• Weight decrease was reported in 3% of patients 1

Central Nervous System Effects

CNS side effects are common but generally mild to moderate in severity. 2

• Headache (19% versus 15% with placebo) 1
• Somnolence/sedation (11% in children/adolescents) 1
• Dizziness (5% in children/adolescents) 1
• Fatigue (8% in children/adolescents) 1
• Irritability (6% in children/adolescents) 1

Cardiovascular Effects

Modest increases in heart rate and blood pressure are expected but are generally well tolerated. 2, 4

• Approximately 5-10% of patients experience potentially clinically important changes in heart rate (≥20 beats per minute) or blood pressure (≥15-20 mmHg) 1
• These changes are statistically but not typically clinically significant 2
• Blood pressure and heart rate increases gradually decrease upon cessation of treatment 4, 5

Dosing-Specific Considerations

At 40 mg BID (80 mg total daily dose), you are at a moderate dose level where side effects may be more pronounced than at lower starting doses. 6

• The American College of Obstetricians and Gynecologists recommends starting at 40 mg once daily, with your BID dosing representing a higher total daily dose 6
• Common adverse effects include nausea, vomiting, fatigue, decreased appetite, abdominal pain, and somnolence 6

Important Safety Monitoring

Close monitoring is required, particularly during the first few months of treatment. 6

• Monitor for suicidality, clinical worsening, and unusual behavioral changes, especially during initial treatment or dose changes 6, 1
• The FDA has issued a black-box warning for suicidal ideation based on meta-analysis data showing higher incidence versus placebo 2
• Rare but serious liver injury has been reported in postmarketing surveillance 2

Discontinuation Rates

• In acute trials, 3% of children/adolescents discontinued due to adverse reactions (versus 1.4% on placebo) 1
• In adult trials, 11.3% discontinued due to adverse reactions (versus 3.0% on placebo) 1
• The majority of adverse events are mild or moderate, with very low incidence of serious adverse events 2

Practical Management Tips

• Most side effects are transient and occur early in treatment 3
• Taking medication with food can reduce gastrointestinal symptoms 1
• No evidence of symptom rebound or acute discontinuation syndrome when stopping treatment 3
• Atomoxetine requires 6-12 weeks to achieve full therapeutic effect, so initial side effects may precede full benefits 6