Dextroamphetamine Works by Boosting Dopamine and Norepinephrine in the Brain

Dextroamphetamine increases the levels of two key brain chemicals — dopamine and norepinephrine — that play a major role in attention, motivation, and focus. If you have ADHD, these chemicals are often in short supply in the parts of the brain that control executive function. Dextroamphetamine helps correct that imbalance.

But what does that actually mean in practical terms? Let's break it down without the medical jargon.

What Dextroamphetamine Does in Your Brain

Think of your brain as a busy office. Dopamine and norepinephrine are like messengers that carry important instructions between workers (neurons). In people with ADHD, these messengers get recycled too quickly — they deliver a message and then get pulled back before the receiving neuron fully processes it.

Dextroamphetamine does two things to fix this:

1. It pushes more messengers out. Dextroamphetamine tells neurons to release more dopamine and norepinephrine into the gaps between brain cells (called synapses). More messengers means signals get through more effectively.
2. It slows the cleanup crew. Normally, a process called "reuptake" pulls dopamine and norepinephrine back into the sending neuron. Dextroamphetamine blocks this reuptake, so the messengers stay in the synapse longer and have more time to do their job.

The result? Better signal transmission in the parts of your brain responsible for attention, impulse control, and motivation. For people with ADHD, this means being able to focus, stay on task, and manage daily responsibilities more effectively.

For narcolepsy, the increased norepinephrine and dopamine promote wakefulness and help prevent the sudden sleep episodes that characterize the condition.

A Note on Monoamine Oxidase

Dextroamphetamine also has a minor effect on an enzyme called monoamine oxidase (MAO), which normally breaks down dopamine and norepinephrine. By slightly inhibiting MAO, Dextroamphetamine further increases the availability of these neurotransmitters. This is also why it's dangerous to combine Dextroamphetamine with MAO inhibitor medications — the combination can cause a dangerous spike in these chemicals, leading to a hypertensive crisis.

How Long Does It Take to Work?

This depends on which formulation you're taking:

• Immediate-release (IR) tablets: You'll typically feel effects within 30–60 minutes of taking a dose.
• Extended-release (ER) capsules (Dexedrine Spansule): These are designed to release medication gradually. You may notice effects within 60–90 minutes, with a slower onset but longer coverage.
• Oral solution (ProCentra): Similar to IR tablets — effects begin within 30–60 minutes.

Most people notice improvements in focus and attention from the first dose. However, finding the right dose may take a few weeks of adjustments with your doctor.

How Long Does Dextroamphetamine Last?

• Immediate-release: Effects last approximately 4–6 hours. This is why IR tablets are often taken 2–3 times per day.
• Extended-release: Effects last approximately 8–12 hours, covering most of the workday or school day with a single morning dose.

The "half-life" of Dextroamphetamine (how long it takes for half the drug to leave your body) is about 10–12 hours in adults. This means it can take a full day for a dose to fully clear your system, which is why taking it too late can cause insomnia.

What Makes Dextroamphetamine Different From Similar Medications?

There are several stimulant medications used for ADHD. Here's how Dextroamphetamine compares:

Dextroamphetamine vs. Adderall (Mixed Amphetamine Salts)

Adderall contains a 3:1 mixture of amphetamine salts — 75% dextroamphetamine and 25% levoamphetamine. Dextroamphetamine is the "pure" dextro form. Some patients find Dextroamphetamine produces less physical jitteriness and anxiety than Adderall because it lacks the levo component, which tends to affect the body's peripheral nervous system more.

Dextroamphetamine vs. Vyvanse (Lisdexamfetamine)

Vyvanse is actually a prodrug of Dextroamphetamine. It's inactive until your body converts it to Dextroamphetamine during digestion. This gives Vyvanse a smoother onset and longer duration, and it's considered to have a lower abuse potential because snorting or injecting it doesn't produce a faster high.

Dextroamphetamine vs. Methylphenidate (Ritalin, Concerta)

Methylphenidate works differently — it primarily blocks reuptake of dopamine and norepinephrine but doesn't increase their release the way amphetamines do. Some patients respond better to one class than the other. If Dextroamphetamine isn't working for you, Methylphenidate may be worth discussing with your doctor.

Dextroamphetamine vs. Atomoxetine (Strattera)

Atomoxetine is a non-stimulant that only affects norepinephrine reuptake. It has no abuse potential and isn't a controlled substance, but it's generally considered less effective for ADHD symptoms than stimulants. It can take 4–6 weeks to reach full effect.

For a complete comparison of alternatives, see our guide to Dextroamphetamine alternatives.

Final Thoughts

Dextroamphetamine works by increasing dopamine and norepinephrine in the brain — two chemicals that are essential for focus, attention, and motivation. It's one of the oldest and most well-studied ADHD medications available, and for many patients, it's highly effective.

If you're currently prescribed Dextroamphetamine and having trouble finding it at the pharmacy, Medfinder can help you check which pharmacies have it in stock — without calling around.