What is the Adderall XR (mixed amphetamine salts) dose equivalent to Vyvanse (lisdexamfetamine) 40 mg?

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Last updated: October 16, 2026 • View editorial policy

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Adderall XR Dose Equivalent to Vyvanse 40mg

The approximate Adderall XR dose equivalent to Vyvanse 40mg is 15-20mg, based on the active amphetamine content and FDA-approved dosing ranges.

Pharmacological Basis for Conversion

Vyvanse (lisdexamfetamine) is a prodrug that is converted to dextroamphetamine after oral ingestion. According to the FDA label, Vyvanse 40mg contains 23.1mg of lisdexamfetamine base, which is enzymatically converted to active d-amphetamine 1.

Adderall XR contains a 3:1 ratio of d-amphetamine to l-amphetamine salts. The FDA label specifies that Adderall XR 15mg provides 9.4mg total amphetamine base equivalence, while Adderall XR 20mg provides 12.5mg total amphetamine base equivalence 2.

Recommended Conversion Approach

Start with Adderall XR 15-20mg when switching from Vyvanse 40mg, then titrate based on clinical response:

  • Vyvanse 40mg → Adderall XR 15-20mg is the most reasonable starting conversion
  • The 2024 AJOG guideline indicates Adderall XR usual starting dose is 10mg with titration by 5mg weekly up to 50mg 3
  • Clinical trials demonstrate both medications have similar efficacy profiles when dosed appropriately 4, 5

Clinical Considerations

Duration of action differs significantly between these formulations:

  • Vyvanse provides approximately 13 hours of coverage due to its prodrug mechanism 1
  • Adderall XR provides approximately 10-12 hours of coverage with its dual-bead extended-release system 2

Individual response varies considerably - research shows that approximately 40% of patients respond to both methylphenidate and amphetamine, while 40% respond to only one 6. A 2014 crossover study found that while both lisdexamfetamine and mixed amphetamine salts showed similar ADHD symptom reduction, some patients showed preferential response to one formulation 4.

Titration Strategy

After initiating the conversion:

  • Assess response weekly using standardized ADHD rating scales 7
  • Increase by 5mg increments if symptom control is inadequate 3
  • Monitor for side effects including appetite suppression, insomnia, cardiovascular changes (pulse, blood pressure) 7
  • Maximum recommended daily dose is 50mg for Adderall XR in most guidelines 3

Important Caveats

This is not a precise 1:1 conversion - the pharmacokinetics differ substantially between a prodrug (Vyvanse) and an immediate/extended dual-release formulation (Adderall XR). The conversion ratio suggested here (40mg Vyvanse ≈ 15-20mg Adderall XR) is based on:

  1. Active amphetamine content comparison from FDA labels 1, 2
  2. Clinical trial dosing equivalencies 4, 5
  3. Guideline-recommended starting doses and titration schedules 3

Individual patient factors require dose adjustment - weight, metabolism (particularly CYP2D6 polymorphisms), comorbidities, and prior stimulant response all influence optimal dosing 6, 2. Close monitoring during the first 2-4 weeks after conversion is essential to ensure adequate symptom control without excessive side effects.

References

3
Guideline

attention-deficit/hyperactivity disorder in pregnancy and the postpartum period.

American Journal of Obstetrics and Gynecology, 2024

7
Guideline

practice parameter for the use of stimulant medications in the treatment of children, adolescents, and adults.

Journal of the American Academy of Child and Adolescent Psychiatry, 2002

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Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.