Amphetamines: Adderall and Vyvanse
This page is a reference summary of published evidence and regulatory documents. It is not a substitute for individual medical advice, and it is not a recommendation to take or avoid any medicine.
Medically reviewed by Dr. Sofia Lindqvist, · Last reviewed 11 August 2026
Adderall is a combination of amphetamine and dextroamphetamine, known as mixed amphetamine salts. Vyvanse is lisdexamfetamine, a prodrug that converts to dextroamphetamine after absorption. Both are central nervous system stimulants.
These are Schedule II controlled substances carrying an FDA boxed warning for abuse, misuse and addiction.
On this page
Formulations
4–6 h
Adderall immediate release
~12 h
Adderall XR
10–14 h
Vyvanse, gradual onset
C-II
US control status
Adderall immediate release
0.5–6 h
Usually more than one dose per day
Adderall XR
1–12 h
Vyvanse (lisdexamfetamine)
1.5–14 h
Must be metabolically converted, so onset is gradual
0h
4h
8h
12h
16h
Approximate window of clinical effect after a single morning dose. The choice between them is usually about how the day is shaped, not about potency.
Because Vyvanse has to be converted before it becomes active, it is sometimes preferred where abuse potential is a specific concern.
Approved uses
ADHD in children and adults, where these drugs improve attention span, reduce impulsivity and decrease hyperactivity.
Narcolepsy, which is the only indication overlapping with the wakefulness agents covered on this site.
How they work
Amphetamines do something more aggressive than reuptake inhibition. As well as blocking reuptake, they reverse the direction of the dopamine and norepinephrine transporters, actively pumping neurotransmitter out of the neuron and into the synapse. They also disrupt vesicular storage, releasing stored neurotransmitter into the cytoplasm where it becomes available for that reverse transport.
Vesicles emptied
transmitter into cytoplasm
Transporter reversed
pumped out, not in
Large, fast catecholamine surge
Reuptake inhibition raises what is already in the synapse. Reversed transport puts new transmitter there. That is the whole difference in one line.
| Modafinil | Methylphenidate | Amphetamines | |
|---|---|---|---|
| Blocks reuptake | Weakly | Yes, potently | Yes |
| Reverses transporters | No | No | Yes |
| Empties vesicles | No | No | Yes |
| Speed of rise | Slow | Fast | Fast and large |
| US schedule | IV | II | II |
That difference in magnitude and speed explains the greater efficacy in severe ADHD, the greater euphoria, the higher abuse liability and the greater cardiovascular load.
The boxed warning
FDA boxed warning
Amphetamines carry an FDA boxed warning — the agency’s most serious warning category — covering abuse, misuse and addiction, and noting risks including serious cardiac events.
None of the wakefulness agents on this site carry a boxed warning. This is the largest formal safety difference between the two classes, and it should be weighted accordingly.
Scheduling
Schedule II, against Schedule IV for modafinil and armodafinil. In practice that means tighter prescribing restrictions, limits on refills and closer monitoring.
Common adverse effects
Appetite loss, insomnia, dry mouth, weight loss, raised heart rate and blood pressure, irritability and mood swings, and a more pronounced end-of-dose decline than the wakefulness agents produce.
Psychosis and mania have been reported. Stopping after sustained use can produce a recognised withdrawal syndrome — fatigue, depression, increased appetite and disturbed sleep — which is why prescribers commonly taper stimulants rather than halting them abruptly.
What is the difference between Adderall and Vyvanse?
Adderall is mixed amphetamine salts, active on absorption. Vyvanse is lisdexamfetamine, a prodrug that must be metabolically converted before it becomes active, which gives it a gradual onset and long duration.
Why are amphetamines Schedule II and modafinil Schedule IV?
Amphetamines reverse transporter direction and empty vesicular stores, producing a much larger and faster rise in synaptic catecholamines. That magnitude and speed is what drives euphoria and abuse liability.
Should amphetamines be stopped abruptly?
Prescribers commonly taper rather than stop suddenly. Discontinuation after sustained use can produce fatigue, depression, increased appetite and disturbed sleep.