Is it safe to add Adderall (amphetamine) 20 mg to Vyvanse (lisdexamfetamine)?

Combining Adderall and Vyvanse is Not Recommended

Adding Adderall 20 mg to Vyvanse therapy is not recommended due to the risk of additive stimulant effects that could significantly increase cardiovascular side effects and other adverse reactions. 1

Pharmacological Considerations

Adderall and Vyvanse are both stimulant medications with similar mechanisms:

• Vyvanse (lisdexamfetamine) is a prodrug that is enzymatically converted to d-amphetamine in the bloodstream 2
• Adderall contains a 3:1 mixture of d-amphetamine and l-amphetamine salts 3
• Both medications ultimately result in d-amphetamine exposure in the body 4

Adding Adderall to Vyvanse would essentially be doubling the amphetamine exposure, which could lead to:

• Increased risk of cardiovascular effects (tachycardia, hypertension)
• Heightened anxiety and insomnia
• Greater appetite suppression
• Potential for increased risk of abuse

Alternative Approaches

Instead of combining these medications, consider these evidence-based alternatives:

1. Optimize current stimulant dosing:

   • The American Academy of Child and Adolescent Psychiatry recommends adjusting timing or splitting doses of a single stimulant medication before adding another 1
   • Maximum daily dose of amphetamine is up to 50 mg daily 1

2. Consider switching medications completely:

   • If Vyvanse is not providing adequate coverage, switching completely to Adderall (or vice versa) may be more appropriate than combining them
   • Pharmacokinetic differences between the medications may explain variable response 4

3. Add a non-stimulant medication instead:

   • Extended-release guanfacine can be used as adjunctive therapy with stimulants when monotherapy is insufficient 1
   • Atomoxetine is another non-stimulant option that has shown efficacy 1

Monitoring Recommendations

If a patient is currently taking both medications (which is not recommended):

• Monitor blood pressure and heart rate frequently
• Assess for sleep disturbances, appetite changes, and mood alterations
• Follow up every 3-4 weeks during dose adjustments 1
• Once stabilized, follow up every 3-6 months 1

Important Considerations

• Food effects: High-fat meals can significantly lower amphetamine concentrations from Adderall XR but have less effect on methylphenidate products 5
• Timing: Lisdexamfetamine has demonstrated efficacy up to 14 hours post-dose in adults 6
• Abuse potential: While lisdexamfetamine was designed with reduced abuse potential in mind, research shows similar peak subjective effects compared to d-amphetamine when taken orally 4

Common Pitfalls to Avoid

• Exceeding maximum recommended daily doses of amphetamine products
• Overlooking comorbidities that may be worsening symptoms 1
• Failing to recognize ADHD as a chronic condition requiring ongoing management 1
• Not considering non-pharmacological interventions like Cognitive Behavioral Therapy which has shown effectiveness for ADHD 1

Remember that stimulant medications are controlled substances with strict regulatory requirements, including DEA-compliant electronic prescribing systems with two-factor authentication 1.