Vyvanse to Adderall Conversion
Direct Conversion Recommendation
There is no established direct dose equivalency between lisdexamfetamine (Vyvanse) and mixed amphetamine salts (Adderall), requiring empiric dosing with subsequent titration based on clinical response. 1
Practical Conversion Approach
Starting Dose Strategy
Start Adderall at approximately 50-70% of the Vyvanse dose as a general guideline, recognizing this is empiric rather than evidence-based. For example:
Adderall can be dosed once daily (XR formulation) or divided into 2-3 doses (immediate-release), with typical adult dosing ranging from 10-50 mg total daily dose 2, 3
Adderall XR should be initiated at 10 mg once daily in the morning when switching from Vyvanse, then titrated by 5 mg weekly based on symptom response 2
Rationale for Empiric Dosing
Lisdexamfetamine is a prodrug that requires enzymatic hydrolysis to convert to active d-amphetamine, while Adderall contains a 3:1 ratio of dextroamphetamine to levoamphetamine in immediate-release form 4, 3, 5
The pharmacokinetic profiles differ substantially: Vyvanse provides gradual release through rate-limited hydrolysis, while Adderall XR uses a dual-bead system releasing half immediately and half after 4 hours 3, 6
Individual response varies significantly between amphetamine formulations, making mathematical dose conversions unreliable 1
Titration Protocol
Increase Adderall by 5-10 mg weekly until optimal ADHD symptom control is achieved or dose-limiting side effects appear 2
Expect immediate therapeutic effects within 1.5 hours of the first Adderall dose—full clinical benefit does not require weeks of treatment 1, 3
Maximum recommended dose is 50 mg daily for adults, though some patients may require up to 60-65 mg with clear documentation that lower doses were insufficient 2
Systematic titration to optimal effect is more important than strict dose calculations, with 70-80% of patients responding when properly titrated 2
Monitoring Requirements
Measure blood pressure and pulse at baseline and weekly during titration, as both medications can produce cardiovascular effects 2, 1
Track sleep quality, appetite changes, and weight at each visit, as these are common adverse effects 2
Use standardized ADHD rating scales weekly during dose adjustment to objectively assess symptom response 2
Key Clinical Differences
Pharmacologic Properties
Vyvanse has lower abuse potential due to its prodrug design requiring enzymatic conversion, making extraction of the stimulant component more difficult 4, 7, 6
Adderall XR provides 12-hour coverage with rapid 1.5-hour onset, while Vyvanse typically lasts 10-13 hours with more gradual onset 3, 5
Both formulations achieve similar efficacy (approximately 80% response rates in monitored clinical trials), though adherence may differ in real-world practice 8
Safety Profile
Common adverse effects are similar: decreased appetite, insomnia, headache, agitation, and tachycardia occur in >10% of patients with both medications 2, 7
Serious outcomes (moderate/major effects) occur in approximately 21% of Vyvanse exposures versus 25% of Adderall exposures based on poison center data 7
Common Pitfalls to Avoid
Do not assume equivalent efficacy at any particular dose ratio—individual response varies significantly between formulations 1
Avoid attempting mathematical conversions based on stimulant equivalency tables—these are unreliable for different amphetamine formulations 1
Do not underdose during the initial switch—starting too low may lead to inadequate symptom control and premature abandonment of the medication 2
Avoid taking Adderall XR with high-fat meals if consistent timing cannot be maintained, as this can affect absorption 1