Switching from Adderall to Vyvanse: Dose Conversion
There is no established direct dose conversion between Adderall and Vyvanse (lisdexamfetamine), so start Vyvanse at 30 mg once daily in the morning regardless of prior Adderall dose, then titrate in 10-20 mg increments at weekly intervals up to a maximum of 70 mg daily. 1
Recommended Approach
Initial Dosing Strategy
- Start all patients at 30 mg Vyvanse once daily in the morning, which is the FDA-approved starting dose for ADHD treatment 1
- This standard starting dose applies regardless of whether the patient was taking 10 mg, 20 mg, or 40 mg of Adderall XR 1
- Take in the morning with or without food to minimize insomnia 1
Titration Schedule
- Increase by 10 mg or 20 mg increments at approximately weekly intervals based on clinical response and tolerability 1
- Allow at least one week between dose increases to properly evaluate therapeutic response 2
- The maximum recommended dose is 70 mg once daily 1
Rationale for This Approach
The lack of direct conversion stems from fundamental pharmacokinetic differences between these medications:
- Vyvanse is a prodrug that must be hydrolyzed in the body to release active d-amphetamine, creating a delayed and prolonged release profile 3, 4, 5
- Vyvanse has a 0.6-1.1 hour longer lag time to reach peak plasma concentrations compared to immediate d-amphetamine 4
- Despite containing only d-amphetamine (versus Adderall's mixed amphetamine salts), the prodrug mechanism creates different pharmacodynamics that don't allow for simple milligram-to-milligram conversion 4, 5
Clinical Monitoring During Transition
What to Assess Before Each Dose Increase
- Therapeutic effects: Improvement in ADHD symptoms using standardized rating scales 2
- Vital signs: Blood pressure and pulse at each visit 2
- Weight: Monitor at each visit for appetite suppression 2
- Side effects: Decreased appetite, insomnia, headache, irritability are most common 1, 3
Timeline Expectations
- Week 1: Start 30 mg, assess tolerability
- Week 2-6: Titrate upward in 10-20 mg increments weekly as needed 1
- Efficacy assessment: Full therapeutic effect should be evaluated after reaching stable dose for at least 2 weeks 2
Common Pitfalls to Avoid
- Don't attempt a direct dose conversion (e.g., switching 30 mg Adderall XR to 30 mg Vyvanse) as this lacks evidence-based support 1
- Don't start at doses higher than 30 mg even if the patient was on high-dose Adderall, as this increases risk of side effects and poor adherence 2
- Don't increase doses more frequently than weekly, as insufficient time between increases prevents accurate assessment of therapeutic response 2
- Don't continue escalating beyond 70 mg if inadequate response occurs; instead consider switching to an alternative medication or adding adjunctive treatment 2
- Don't dose in the afternoon or evening due to insomnia risk 1
Special Considerations
Why Patients May Need Different Doses
Research shows that 41% of medication-naive adults with ADHD require switching between stimulant families (methylphenidate vs. amphetamine) due to poor tolerability, and this cannot be predicted by baseline characteristics 6. This underscores why standardized titration from a conservative starting dose is necessary rather than attempting dose conversion.