Switching from Atomoxetine to Qelbree (Viloxazine ER): Washout Period
No washout period is required when switching from atomoxetine to viloxazine ER (Qelbree) for ADHD treatment. A direct switch with a brief cross-taper is the recommended approach based on clinical trial data and pharmacological considerations.
Evidence-Based Switching Protocol
Direct Transition Without Washout
A 5-day atomoxetine washout was used in one comparative study, but this was for research methodology purposes rather than clinical necessity 1. In clinical practice, direct switching or brief cross-tapering is both safe and effective.
Clinical trial data demonstrates that viloxazine ER can be safely co-administered with other ADHD medications without requiring a washout period 2. The phase 4 study showed excellent tolerability (85.7% completion rate) when viloxazine ER was added to ongoing psychostimulant therapy 2.
The pharmacological profiles of atomoxetine and viloxazine ER do not create overlapping toxicities or dangerous pharmacodynamic interactions that would necessitate a washout period 3, 4. Both are norepinephrine-modulating agents, but viloxazine's additional serotonergic activity does not create contraindications for direct switching 3.
Recommended Switching Approach
Option 1: Direct Switch (Most Common)
- Discontinue atomoxetine and start viloxazine ER at 200 mg once daily the following day 3
- This approach is supported by the fact that atomoxetine can be discontinued abruptly without rebound effects or discontinuation syndrome 5
- Viloxazine ER shows therapeutic effects within 1-2 weeks, with 86% of patients reporting positive response by 2 weeks 1, 6
Option 2: Brief Cross-Taper (For Symptom Continuity)
- Continue atomoxetine at full dose while initiating viloxazine ER 200 mg for 3-7 days
- Then discontinue atomoxetine and continue viloxazine ER monotherapy
- This mirrors the successful cross-taper approach used when switching from stimulants to atomoxetine 7
Clinical Advantages of This Switch
Patients switching from atomoxetine to viloxazine ER demonstrate significantly greater symptom improvement 1. In pediatric patients, ADHD-RS-5 scores improved to 13.9 ± 10.2 on viloxazine ER versus 33.1 ± 12.1 on atomoxetine (p < 0.00001) 1.
Tolerability is superior with viloxazine ER: only 4% discontinued due to side effects (fatigue) compared to 36% who discontinued atomoxetine for various adverse effects including GI upset, irritability, and fatigue 1.
Patient preference strongly favors viloxazine ER: 96% of patients preferred viloxazine ER over atomoxetine after switching 1.
Important Safety Considerations
Monitor for Serotonin Syndrome (First 24-48 Hours)
While viloxazine ER has serotonergic activity, the American Academy of Child and Adolescent Psychiatry recommends caution primarily when combining with OTHER serotonergic agents 3. Since atomoxetine is primarily a norepinephrine reuptake inhibitor without significant serotonergic effects, this risk is minimal during the switch.
Monitor for agitation, confusion, tachycardia, hypertension, dilated pupils, tremor, or diaphoresis during the first 48 hours if using a cross-taper approach 3.
Cardiovascular Monitoring
- Both medications can increase blood pressure and heart rate 8, 7
- Check vital signs at baseline and within 1-2 weeks after the switch 7
Suicidality Monitoring
- Both atomoxetine and viloxazine ER carry warnings for suicidal ideation, particularly in children and adolescents 8, 3, 6
- Maintain close monitoring during the transition period, especially in the first few months 8
Common Pitfalls to Avoid
Don't assume a washout is needed based on general switching principles: Unlike switching between biologic therapies where 4 half-lives (approximately) may be recommended 8, ADHD non-stimulants without overlapping toxicities or dangerous pharmacodynamic interactions do not require formal washout periods 8.
Don't delay the switch unnecessarily: Atomoxetine non-responders (36% discontinued for side effects in one study) benefit from rapid transition to viloxazine ER, which shows response within 1-2 weeks 1, 6.
Don't expect immediate effects: While faster than atomoxetine (1-2 weeks vs 4 weeks), viloxazine ER still requires patience compared to stimulants 1, 6. Full therapeutic effects may take 2-4 weeks 9.
Don't forget to titrate viloxazine ER appropriately: Start at 200 mg daily and titrate by 200 mg increments weekly based on response, up to a maximum of 600 mg daily 3, 4.