What are the side effects of Strattera (atomoxetine)?

Side Effects of Strattera (Atomoxetine)

Strattera causes common gastrointestinal side effects (nausea, vomiting, abdominal pain), decreased appetite, somnolence, and cardiovascular changes (increased heart rate and blood pressure), with less common but serious risks including suicidal ideation (FDA black box warning), rare hepatotoxicity, and sexual dysfunction in adults. 12

Common Side Effects by Population

Children and Adolescents (Most Frequent ≥5%)

The most common side effects occurring in at least 5% of pediatric patients and at least twice the rate of placebo include 12:

• Gastrointestinal: Nausea (10%), vomiting (11%), abdominal pain (18%)
• Appetite/Weight: Decreased appetite (16%), weight loss (3%)
• Neurological: Headache (19%), somnolence (11%), dizziness (5%)
• General: Fatigue (8%), irritability (6%)

Adults (Most Frequent ≥5%)

The most common side effects in adults occurring at ≥5% and at least twice placebo rates include 2:

• Gastrointestinal: Constipation, dry mouth, nausea
• Appetite: Decreased appetite
• Neurological: Dizziness
• Genitourinary: Erectile dysfunction, urinary hesitation

Cardiovascular Effects

Monitor heart rate and blood pressure regularly, as atomoxetine increases both parameters. 11

• Average increases: 1-2 beats/min for heart rate, 1-4 mmHg for blood pressure
• 5-15% of patients experience more substantial increases (≥20 bpm or ≥15-20 mmHg) 1
• Risk of serious cardiovascular events is extremely low 1
• Obtain cardiac history (personal and family) before initiating treatment, including history of sudden death, Wolff-Parkinson-White syndrome, hypertrophic cardiomyopathy, and long QT syndrome 11
• Consider ECG if cardiac risk factors present 1

Serious but Less Common Side Effects

Suicidal Ideation (FDA Black Box Warning)

• Increased risk of suicidal thoughts, particularly early in treatment 1
• Large meta-analysis (N=3883) found no completed suicides and no statistically significant association, but warning remains 3
• Monitor closely, especially during initial treatment period

Hepatotoxicity (Extremely Rare)

• Rare cases of severe liver injury, including cases requiring liver transplantation 13
• Presents as reversible hepatitis in most documented cases
• Discontinue immediately if jaundice or laboratory evidence of liver injury develops

Growth Effects

• Growth delays (height and weight) observed in first 1-2 years of treatment 11
• Most pronounced in children taller or heavier than average at baseline
• Growth typically returns to expected trajectories after 2-3 years 1
• Comprehensive review suggests growth reductions are reversible long-term 3

Sexual Dysfunction (Adults)

• Erectile dysfunction (21% in CYP2D6 poor metabolizers vs 9% in extensive metabolizers) 2
• Ejaculation disorders (6% in poor metabolizers vs 2% in extensive metabolizers) 2
• Urinary hesitation/retention (6% in poor metabolizers vs 1% in extensive metabolizers) 24
• These effects typically resolve within 2 days of discontinuation 45

Dosing-Related Considerations

Initial somnolence and gastrointestinal symptoms are particularly common if dosage is increased too rapidly 11. Titrate slowly to minimize these effects.

CYP2D6 Poor Metabolizers

Poor metabolizers experience significantly higher rates of certain side effects 22:

• Dry mouth (35% vs 17% in extensive metabolizers)
• Constipation (11% vs 7%)
• Insomnia (19% vs 11%)
• Erectile dysfunction (21% vs 9%)
• Hyperhidrosis (15% vs 7%)

Dosage adjustment is necessary when coadministered with potent CYP2D6 inhibitors (paroxetine, fluoxetine, quinidine) or in known poor metabolizers 2.

Discontinuation Rates

• 3.0% of children/adolescents discontinued due to adverse events in acute trials 2
• 11.3% of adults discontinued in acute trials 2
• Most common reasons for discontinuation: insomnia, nausea, irritability, somnolence, aggression 2

Time Course of Side Effects

Most common adverse events appear within the first week of treatment 5. Resolution times vary:

• Rapid resolution (days): Some gastrointestinal effects, cardiovascular changes upon discontinuation
• Lingering resolution (3-53 days median): Sexual side effects, other effects 5
• Blood pressure and heart rate return to baseline upon discontinuation 5

Clinical Monitoring Recommendations

1. Baseline: Obtain personal and family cardiac history, consider ECG if risk factors present 1
2. Ongoing: Monitor heart rate, blood pressure, growth parameters (height/weight), mood/suicidal ideation 1
3. Educate patients explicitly about genitourinary and sexual side effects, as these may not be spontaneously reported 4