Is it safe to co‑prescribe atomoxetine (Strattera) with sertraline, and what dosing and monitoring guidelines should be followed?

Co-prescribing Atomoxetine (Strattera) and Sertraline

Atomoxetine and sertraline can be safely co-prescribed, but sertraline significantly increases atomoxetine blood levels requiring dose adjustment—start atomoxetine at 0.5 mg/kg/day and only increase to the usual target of 1.2 mg/kg/day after 4 weeks if tolerated, with close monitoring for side effects especially in the first weeks. 1, 2

Critical Drug Interaction: CYP2D6 Inhibition

Sertraline inhibits CYP2D6, the primary enzyme metabolizing atomoxetine, increasing atomoxetine exposure 6- to 8-fold with 3- to 4-fold higher peak concentrations. 2 This pharmacokinetic interaction is clinically significant and mandates dosing modifications.

Dosing Algorithm When Combining

For children and adolescents ≤70 kg:

• Start atomoxetine at 0.5 mg/kg/day (half the usual starting dose) 2
• Maintain this dose for minimum 3 days, ideally 4 weeks 2
• Only increase to target of 1.2 mg/kg/day if symptoms persist and medication is well-tolerated 2
• Maximum dose: 1.4 mg/kg/day or 100 mg, whichever is less 2

For adolescents >70 kg and adults:

• Start atomoxetine at 40 mg/day 2
• Increase after minimum 3 days to 80 mg/day only if needed and tolerated 2
• Maximum dose: 100 mg/day 2

Safety Monitoring Requirements

First 24-48 Hours After Initiation or Dose Changes

Monitor closely for serotonin syndrome when combining these serotonergic agents. 1 While the risk is lower than with MAOIs, caution is warranted when combining two non-MAOI serotonergic drugs. 1

Serotonin syndrome symptoms include: 1

• Mental status changes (confusion, agitation, anxiety)
• Neuromuscular hyperactivity (tremors, clonus, hyperreflexia, muscle rigidity)
• Autonomic hyperactivity (hypertension, tachycardia, diaphoresis, vomiting, diarrhea)
• Advanced symptoms: fever, seizures, arrhythmias, unconsciousness

Ongoing Monitoring (Throughout Treatment)

Cardiovascular monitoring is essential for atomoxetine: 1

• Obtain personal and family cardiac history before starting 1
• Monitor heart rate and blood pressure at each visit 1
• Atomoxetine may increase HR and BP, though typically mild 1
• Consider ECG if cardiac risk factors present 1

Suicidality monitoring for both medications: 1

• Both atomoxetine and sertraline carry black box warnings for suicidal ideation in youth 1
• Monitor closely during first months and after dose changes 1
• Atomoxetine: 12 trials showed increased suicidal ideation risk in children/adolescents 1
• Sertraline: pooled risk difference 0.7% (NNH=143) 1

Behavioral activation/agitation monitoring: 1

• More common in younger children and with dose increases 1
• Can occur when combining drugs that inhibit SSRI metabolism 1
• Educate families about this potential side effect in advance 1

Common Side Effects to Anticipate

Atomoxetine side effects (may be amplified by elevated levels): 1

• Nausea, vomiting, fatigue, decreased appetite, abdominal pain, somnolence
• Initial somnolence and GI symptoms especially if dose increased too rapidly 1
• 7% of population are CYP2D6 poor metabolizers with higher plasma levels and increased adverse effects 1

Sertraline side effects: 1

• Dry mouth, nausea, diarrhea, headache, insomnia, dizziness
• Most adverse effects emerge within first few weeks 1

Clinical Evidence for Combination

The combination has been studied and found safe, though efficacy data are mixed: 3, 4

• One study (N=146) found no additional benefit of adding atomoxetine to sertraline for depression 3
• Another study (N=127) showed atomoxetine plus fluoxetine was well-tolerated in pediatric ADHD with comorbid depression/anxiety 4
• Combined therapy showed greater blood pressure and pulse increases than monotherapy 4

Key Clinical Pitfalls to Avoid

Do not use standard atomoxetine dosing when co-prescribing with sertraline—this is the most critical error that leads to excessive side effects and treatment discontinuation. 2

Do not combine with MAOIs—contraindicated due to risk of serious, potentially fatal reactions including hyperthermia, rigidity, and autonomic instability. 2

Do not abruptly discontinue sertraline if patient is stabilized on combination therapy, as this may suddenly decrease atomoxetine metabolism and cause withdrawal symptoms. 1

Avoid in patients with:

• Narrow angle glaucoma 5
• Significant cardiovascular disease 1
• Long QT syndrome (for sertraline) 1
• Concurrent MAOI use 2

Additional Considerations

Atomoxetine can be taken with or without food and discontinued without tapering. 2 However, sertraline should be tapered to avoid discontinuation syndrome (dizziness, nausea, paresthesias, anxiety). 1

The combination does not increase cardiovascular effects beyond atomoxetine alone based on studies with methylphenidate, though monitoring remains essential. 2

Pregnancy/lactation: Exercise caution; atomoxetine should be closely monitored or avoided in pregnant/lactating patients. 5