What are the common and serious side effects of Strattera (atomoxetine)?

Strattera (Atomoxetine) Side Effects

The most common side effects of Strattera include gastrointestinal symptoms (upset stomach, nausea, decreased appetite), initial somnolence, headache, dizziness, and mood changes, with rare but serious risks including suicidal ideation, severe liver injury, and cardiovascular effects. 1

Common Side Effects

In Children and Adolescents

• Gastrointestinal disturbances: Upset stomach, nausea, vomiting, and abdominal pain are among the most frequently reported adverse events 1, 2
• Decreased appetite: Commonly occurs, particularly if dosage is increased too rapidly 3, 1
• Dizziness and tiredness: Frequently reported, especially during initial treatment 1
• Mood swings: Can occur in pediatric patients 1
• Headache: One of the most common adverse events 4
• Somnolence: Initial drowsiness is common, particularly if dose escalation is too rapid 3, 4

In Adults

• Dry mouth: Very common in adult patients 1, 5
• Constipation: Frequently reported in adults 1, 5
• Nausea and decreased appetite: Common gastrointestinal effects 1, 5
• Dizziness: Commonly experienced 1, 5
• Sexual side effects: Including dysuria and sexual dysfunction 1, 5
• Insomnia: Can occur despite the medication's potential for causing somnolence 5, 6
• Sweating and palpitations: Reported more frequently than with placebo 5, 6

Important note: These gastrointestinal and somnolence-related side effects are generally transient and most pronounced during the initial weeks of treatment, particularly if dosage is increased too rapidly 2, 4

Serious Side Effects Requiring Immediate Attention

Psychiatric Effects

• Suicidal ideation: Atomoxetine carries a black-box warning for increased risk of suicidal thoughts, particularly in children and adolescents, based on meta-analysis showing significantly higher incidence versus placebo 3, 4
• Mood lability and dysphoria: Can occur, especially in younger children 3
• Psychotic symptoms: Hallucinations and other psychotic symptoms are uncommon but serious adverse effects 3

Hepatotoxicity

• Severe liver injury: Rare but serious; postmarketing data identified three cases of liver-related adverse events probably related to atomoxetine 4
• Hepatitis: Rare occurrence requiring monitoring 3

Cardiovascular Effects

• Modest increases in heart rate and blood pressure: Generally well tolerated but require monitoring 3, 5
• Palpitations: Reported more frequently than placebo 5, 6
• Cardiac history screening is essential: Expand history to include Wolf-Parkinson-White syndrome, sudden death in family, hypertrophic cardiomyopathy, and long QT syndrome 3

Urogenital Effects

• Urinary retention: Problems starting or maintaining urine stream, inability to fully empty bladder 1
• Priapism: Rare but serious; erections lasting more than 4 hours require immediate medical evaluation due to potential for permanent damage 1

Allergic Reactions

• Serious allergic reactions: Including trouble breathing, swelling, hives, or other severe allergic manifestations requiring immediate medical attention 1

Growth Effects in Children

• Initial slowing of growth: Height and weight velocity may decrease initially 3, 4
• Long-term normalization: Growth parameters typically return to normal with continued treatment; no significant long-term impairment demonstrated 2, 4
• Regular monitoring required: Height and weight should be checked frequently during treatment 1

Discontinuation and Tolerance

• No rebound symptoms: Atomoxetine discontinuation is not associated with symptom rebound 2, 4
• No acute discontinuation syndrome: Unlike stimulants, atomoxetine can be stopped without significant withdrawal effects 2
• Low discontinuation rates: Very low incidence of discontinuation-emergent adverse events 4
• No abuse potential: Atomoxetine carries negligible risk of abuse or diversion and is not a controlled substance 5, 6

Special Population Considerations

Pregnancy and Breastfeeding

• Pregnancy: Does not appear associated with major congenital malformations or significant adverse obstetrical outcomes, though data are limited; possible increased risk for spontaneous abortion (confounding by indication cannot be ruled out) 3
• Breastfeeding: Caution advised; no published studies exist, but based on pharmacokinetics (low molecular weight, long half-life), atomoxetine will likely be present in breast milk with unknown effects on nursing infants 3

CYP2D6 Poor Metabolizers

• Higher plasma concentrations: Poor metabolizers have approximately 10-fold higher steady-state concentrations 7
• Similar adverse event profile: Despite higher concentrations, frequency and severity of adverse events are similar regardless of CYP2D6 phenotype 7, 4
• Drug interactions: CYP2D6 inhibitors (e.g., paroxetine) can produce similar pharmacokinetic changes in extensive metabolizers 7

Clinical Monitoring Recommendations

• Regular cardiovascular checks: Blood pressure and heart rate monitoring during treatment 1
• Growth monitoring: Height and weight checks in children 1
• Hepatic function: Consider monitoring given rare hepatotoxicity risk 4
• Psychiatric symptoms: Monitor for emergence of suicidal ideation, mood changes, or psychotic symptoms 3, 4