Timing of Vyvanse Administration
Vyvanse (lisdexamfetamine) should be taken in the morning, and afternoon doses must be avoided due to the potential for insomnia. 1
Official FDA Guidance on Timing
The FDA-approved prescribing information explicitly states:
- Take lisdexamfetamine orally in the morning with or without food 1
- Avoid afternoon doses because of the potential for insomnia 1
- The medication can be taken at any time in the morning, regardless of food intake 1
Clinical Rationale for Morning Dosing
Vyvanse has demonstrated efficacy extending 14 hours post-dose in adults, making it a long-acting stimulant that maintains therapeutic effects late into the day. 2 This extended duration of action is precisely why afternoon or evening administration would interfere with normal sleep patterns.
The prodrug mechanism of lisdexamfetamine involves enzymatic conversion in red blood cells to the active d-amphetamine, which then exerts its therapeutic effects throughout the day. 2, 3 This pharmacological profile supports once-daily morning administration as the optimal dosing strategy.
Comparison with Other Stimulants
Guidelines for other CNS stimulants support similar timing restrictions:
- Methylphenidate or dextroamphetamine for daytime sedation should have a second dose given at lunch, preferably no later than 2:00 PM 4
- Caffeine's last dose should be given no later than 4:00 PM 4
- Bupropion's second dose should be given before 3 PM to minimize insomnia risk 4
Key Clinical Considerations
The single daily dose should never be divided - patients must take at least one full capsule or chewable tablet per day, as splitting doses is not recommended. 1
If patients experience inadequate symptom control with morning dosing alone, the solution is dose titration (10-20 mg increments weekly up to 70 mg maximum) rather than adding an afternoon dose. 1
Attempting to extend Vyvanse's effects into the evening through timing manipulation could lead to unpredictable cardiovascular stress, as the medication already increases heart rate and blood pressure. 5