How Amphetamine/Dextroamphetamine XR Works — Without the Medical Jargon

You've probably heard that Amphetamine/Dextroamphetamine XR (generic Adderall XR) "increases dopamine in the brain." But what does that actually mean? And how does a single morning capsule keep working for up to 12 hours?

This guide breaks down how the medication works inside your body, in plain language — so you understand what's happening and why it helps with ADHD.

What It Does in Your Brain

To understand how Amphetamine/Dextroamphetamine XR works, it helps to know a little about how the ADHD brain is different.

The ADHD Brain: A Quick Primer

People with ADHD tend to have lower-than-normal activity of two key brain chemicals (neurotransmitters):

• Dopamine — involved in motivation, reward, and focus
• Norepinephrine — involved in alertness, attention, and energy

When these neurotransmitters are underactive, it becomes harder to pay attention, stay organized, control impulses, and complete tasks. That's the core of ADHD.

How the Medication Fixes This

Amphetamine/Dextroamphetamine XR works in two main ways:

1. It blocks reuptake. Normally, after dopamine and norepinephrine are released into the gap between brain cells (the synapse), they get quickly pulled back into the cell that released them — a process called "reuptake." Amphetamine blocks this reuptake, so more dopamine and norepinephrine stay in the synapse longer.
2. It increases release. Amphetamine also pushes neurons to release more dopamine and norepinephrine in the first place. This is what makes it different from medications like Methylphenidate (Ritalin, Concerta), which primarily block reuptake without significantly increasing release.

The result: more dopamine and norepinephrine are available in the brain areas that control attention, focus, and impulse control. For most people with ADHD, this translates to better concentration, less impulsivity, and an improved ability to get things done.

The Four Salts

Amphetamine/Dextroamphetamine XR contains four different amphetamine salts in a specific ratio (3.1 parts dextroamphetamine to 1 part levoamphetamine):

• Dextroamphetamine sulfate
• Amphetamine sulfate
• Dextroamphetamine saccharate
• Amphetamine aspartate monohydrate

Dextroamphetamine is the more potent form and primarily drives the focus-enhancing effects. Levoamphetamine contributes more to physical alertness and energy. The combination of both is thought to provide a more balanced effect than either alone.

How Long Does It Take to Work?

Amphetamine/Dextroamphetamine XR starts working within 30 to 60 minutes of taking it. Here's the timeline:

• 0–30 minutes: The immediate-release beads in the capsule begin dissolving and releasing medication.
• 1–2 hours: You'll likely feel the full initial effect — improved focus, reduced impulsivity, increased alertness.
• 4–6 hours: The delayed-release beads begin releasing the second wave of medication, extending the effect.
• 8–12 hours: Medication gradually wears off. Most people notice effects fading by late afternoon or early evening.

The two-bead design is what gives the "XR" its extended duration. It mimics taking two doses — one in the morning and one at midday — but from a single capsule.

How Long Does It Last?

Amphetamine/Dextroamphetamine XR is designed to provide up to 12 hours of symptom control. In practice, the duration varies from person to person based on factors like:

• Your metabolism — Faster metabolizers may find the effect wears off sooner.
• Your dose — Higher doses tend to last longer.
• Whether you ate — A high-fat meal can delay the onset but doesn't reduce overall effectiveness.
• Urine pH — Acidic urine speeds up elimination of amphetamine, while alkaline urine slows it down. This is why acidic foods and drinks (like orange juice or vitamin C) can reduce effectiveness.

The medication's half-life is approximately 9 to 14 hours in adults, meaning it takes that long for half the drug to be eliminated from your body.

What Makes It Different From Other ADHD Medications?

XR vs. IR (Immediate-Release)

The immediate-release version (Adderall / Amphetamine/Dextroamphetamine IR) lasts about 4 to 6 hours and is typically taken 2 to 3 times per day. The XR version lasts up to 12 hours with a single dose, which means:

• No midday dose needed (helpful for students and working adults)
• Smoother effect with less "peak and crash"
• Lower risk of rebound symptoms between doses

Amphetamine vs. Methylphenidate

The other major class of ADHD stimulants is methylphenidate (Ritalin, Concerta, Focalin). The key differences:

• Amphetamine both blocks reuptake and increases release of dopamine/norepinephrine. Methylphenidate primarily blocks reuptake only.
• Some patients respond better to one class than the other — it's not uncommon to try both before finding the best fit.
• Side effect profiles are similar but not identical.

For a full comparison of options, see our guide to alternatives to Amphetamine/Dextroamphetamine XR.

Amphetamine/Dextroamphetamine XR vs. Vyvanse

Vyvanse (Lisdexamfetamine) is a prodrug — meaning it's inactive until your body converts it into dextroamphetamine. This conversion step gives it a slower onset and may lower abuse potential. Vyvanse contains only dextroamphetamine (not the mixed salts found in Amphetamine/Dextroamphetamine XR) and lasts about 10 to 14 hours.

Final Thoughts

Amphetamine/Dextroamphetamine XR works by boosting dopamine and norepinephrine — two brain chemicals that are underactive in people with ADHD. Its dual-bead design delivers medication in two phases, providing smooth, all-day symptom control from a single morning dose.

Understanding how your medication works can help you use it more effectively and have better conversations with your doctor. If you have questions about side effects or need help finding it in stock, we've got guides for that too.