Prescribing Amphetamine - Dextroamphetamine

Why Adderall Still Matters

Mixed amphetamine salts, the drug we call Adderall, are among the most effective medications in all of psychiatry. For adult ADHD, the effect size of amphetamines sits around 0.9 and, in some analyses, higher; that is roughly double the effect of any non-stimulant, and it dwarfs the effect sizes we accept as meaningful for antidepressants. When a correctly diagnosed patient responds, the change is often not subtle. People finish tasks they have avoided for years, stop losing their keys and their jobs, and describe, accurately, feeling like themselves for the first time.

Amphetamine is also one of the oldest drugs in the field. Charles Bradley stumbled onto its "brain medicine" effect in children in 1937, decades before ADHD had its modern name. Adderall itself is a repackaging story: the same mixed-salts formula was once marketed as the weight-loss drug Obetrol, then relaunched in 1996 as "Adderall," positioned as the thing that was not Ritalin. The pendulum of which stimulant is the reigning boogeyman has swung back and forth ever since.

None of that history changes the core clinical fact: for adults with genuine ADHD, amphetamines tend to outperform methylphenidate, and roughly 80% of patients who have tried both prefer Adderall. The trade-off is equally clear. Amphetamine is a Schedule II controlled substance with real abuse and diversion potential, a meaningful cardiovascular and psychiatric side-effect profile, and a diagnosis (ADHD) that is genuinely hard to make well and easy to fake.

This guide is about prescribing it well: making the diagnosis honestly, dosing to effect without wandering into the danger zone, managing the crash and the appetite loss and the sleep, screening the heart, watching for diversion, and knowing when the right stimulant is actually a different one. The thesis throughout: amphetamine is a high-value, high-responsibility drug. The skill is not in prescribing it, it's in the diagnosis, the dose discipline, and the monitoring around it.

Part 1: Indications, Who Is Adderall For?

FDA-Approved Uses

• ADHD in children and adults (mixed amphetamine salts, IR and XR).
• Narcolepsy.
• Binge eating disorder, approved specifically for lisdexamfetamine (Vyvanse), not for mixed amphetamine salts. (The only FDA-approved medication for BED; NNT ≈ 4 for remission.)

The Evidence Base in ADHD

For adults, amphetamines are the more effective stimulant class. The head-to-head and meta-analytic picture (Cortese et al., Lancet Psychiatry 2018, among others):

• Amphetamines are modestly more effective than methylphenidate overall, and the advantage is most pronounced in adults; methylphenidate tends to win in children under 18.
• Effect sizes commonly cited: amphetamine-class ~0.6–1.3 depending on the analysis and population, versus methylphenidate ~0.5–0.9.
• In a large real-world survey (ADDitude, n≈4,425), 52% of adult Adderall users rated it "very effective" vs. 41% for Ritalin, and only 12% called Adderall ineffective vs. 22% for Ritalin.
• About 80% of patients who have tried both prefer Adderall.

Off-Label and Emerging Uses (Know These Are Weaker)

• Depression augmentation and bipolar depression augmentation: promising in early trials, but larger Phase III studies were negative. Not a reliable indication.
• Low-dose stimulant for age-related cognitive/energy decline in medically ill older adults (methylphenidate 5–20 mg/day is better studied here than amphetamine).
• Cancer-related fatigue and "brain fog," chronic fatigue, post-viral fatigue: used clinically, thin evidence.

Who Is a Good Candidate

• Genuine ADHD: childhood-onset (before age 12), cross-setting impairment, mimics excluded, ideally scale-documented.
• Adults, particularly those who have already responded to or prefer amphetamine.
• No prohibitive cardiac disease, no active psychosis or mania, no active substance use disorder.

Who Is a Poor Candidate (Proceed With Caution or Choose Another Agent)

• Active or high-risk psychotic disorder or bipolar I (mania/psychosis risk; amphetamine is worse than methylphenidate here).
• Active substance use disorder or high diversion risk (favor a non-stimulant, or Vyvanse if a stimulant is essential).
• Significant cardiovascular disease or uncontrolled hypertension.
• Prominent anxiety/obsessive-compulsive traits, which stimulants can worsen.
• The patient whose "ADHD" is actually untreated sleep deprivation, overload, or another disorder: treat the real problem.

Part 2: Before You Start, Workup and Candidacy

The workup for amphetamine is more clinical than laboratory. There is no routine blood level or lab panel to follow; the pre-start effort goes into the diagnosis, the heart, and the abuse screen.

The Candidacy Checklist

Absolute Contraindications

• Cardiomyopathy
• Prolonged QT or short QT syndrome
• Brugada syndrome
• Wolff-Parkinson-White syndrome
• Marfan syndrome
• Uncontrolled hypertension; recent MI or unstable angina
• Active psychosis (stimulants worsen it)
• Concurrent or recent (within 14 days) MAOI use: risk of hypertensive crisis.

Part 3: How to Start and Dose

Formulations: What Adderall Actually Is

Adderall is a mixed-salts amphetamine in a 3:1 ratio of dextro- to levo-amphetamine (75% d, 25% l), combining four amphetamine salts to produce (in theory) a smoother rise and fall than pure dextroamphetamine.

Starting Dose and Titration

• Start low. A typical adult start is Adderall IR 5 mg once or twice daily, or Adderall XR 10 mg every morning. In children, weight-based dosing is a useful anchor: ~0.5 mg/kg/day for amphetamines (roughly half the mg/kg of methylphenidate).
• Titrate every ~3–7 days by 5 mg (IR) or ~5–10 mg (XR) increments as tolerated, guided by response and side effects.
• Strategy that works well: start IR to find the effective total daily dose, then convert to an equivalent XR for once- or twice-daily convenience and smoother coverage.
• Trial length: give each agent a 1–2 month trial, re-rating symptoms; ≥50% improvement on the scale is a good response.

Dosing Ranges and the Safety Zones

• Usual range: 5–40 mg/day for adult ADHD; the label max is 40 mg/day for adult ADHD and 60 mg/day for narcolepsy/severe ADHD.

Think in three zones:

• Safe zone: <40 mg/day.
• Gray zone: 40–60 mg/day, sometimes justified for documented severe symptoms and clear functional impairment, with closer monitoring.
• Danger zone: >60 mg/day, no evidence justifies it, and animal models show dopaminergic neurotoxicity at these ranges. If a patient isn't responding at max dose, switch agents, don't climb higher.

Conversions (Approximate, Verify by Patient Experience)

• Amphetamine to methylphenidate: Adderall 10 mg ≈ Ritalin 20 mg (amphetamine roughly twice as potent).
• Adderall to Vyvanse: multiply the Adderall dose by ~2.6 (e.g., Adderall 20 mg ≈ Vyvanse 50 mg; 30 mg ≈ 70 mg).
• Conversion tables are approximations. Absorption differs across formulations; trust the patient's reported effect and side effects over the table.

Part 4: Monitoring

Amphetamine has no therapeutic drug level and no mandatory lab schedule. Monitoring is clinical and vital-sign-based.

No routine ECG, no routine bloodwork in the stable, well-responding, low-risk patient. Escalate monitoring in the elderly, in anyone with cardiac risk, and whenever you add an interacting drug.

Part 5: Side Effects and How to Manage Them

The governing principle: most amphetamine side effects are dose-dependent, front-loaded, and manageable, and many fade over the first few weeks. Manage them early, because side effects (not lack of efficacy) are the usual reason patients quit or self-discontinue.

Appetite Suppression and Weight Loss

The most common side effect, about 35% early on. Expect 8–10 lb of loss over the first months, which should then stabilize. Amphetamines suppress appetite more than methylphenidate.

Management:

• Eat before the dose and again after it wears off (breakfast pre-dose, a real dinner post-wear-off).
• Front-load calories and protein when appetite is present.
• Persistent or excessive loss leads to dose reduction, switch stimulant, or drug holidays.
• In children, track growth; frank deceleration warrants dose reduction and holidays.

The "Adderall Crash"

Roughly half of patients report an evening rebound as the medication wears off: unmotivation, irritability, fatigue without restorative sleep, general misery. It is worse with immediate-release.

Management:

• Switch to a formulation that tapers off gradually (Adderall XR, or Vyvanse, which is the smoothest). For IR users, build an artificial taper: e.g., 20 mg morning, 10 mg midday, 5 mg late afternoon rather than a single big dose that falls off a cliff.
• L-tyrosine ~500 mg, 1–2 hours before the expected wear-off is a reasonable adjunct (dopamine precursor supporting synthesis during the rebound).
• Protect sleep, crash plus poor sleep compounds the misery.

Sleep Disturbance

About 28%, mostly when drug is still active at bedtime. (Occasionally sleep improves, as reduced rumination or the wear-off "crash" lets the patient wind down.)

Management:

• Dose earlier in the day; avoid late-afternoon IR doses.
• Use a shorter-acting form or trim the last dose.
• Do not let the stimulant paper over chronic sleep deprivation, fix the sleep.

Cardiovascular

Stimulants raise blood pressure (~1–8 mm Hg systolic) and heart rate. The absolute cardiovascular risk in healthy adults is small (roughly a 0.1 percentage-point increase in 10-year MI risk for the average user), but it scales with dose and with baseline risk.

Management:

• Track BP and HR at baseline and dose changes.
• Sustained elevation leads to reduce dose, or add/optimize antihypertensive management; an alpha-2 agonist (clonidine, guanfacine) can both treat ADHD synergistically and blunt sympathomimetic effects.
• Levo-amphetamine drives more of the cardiac effect, prefer dextro-dominant formulations (Dexedrine/Vyvanse are 100% d) in cardiac-risk patients; avoid Evekeo (1:1).

Psychiatric: Irritability, Mania, Psychosis

• Irritability (~25%) is less common than feared and often improves; more of a problem in misusers than in true ADHD. If it occurs, reduce dose or switch to methylphenidate (safer profile).
• Mania/psychosis is the serious one. Amphetamines carry ~2× the psychosis risk of methylphenidate; high doses (e.g., ~2× FDA max in narcolepsy) carry a ~12-fold psychosis risk. A single dose can precipitate psychosis in ~30% of patients in remission from a psychotic illness. Screen before starting; if it emerges, stop the amphetamine and reassess the diagnosis.

Dry Mouth (Xerostomia)

Common. Manage with oral rinses (Biotene, SalivaMAX); if gingival recession develops, pilocarpine is FDA-approved for xerostomia. Encourage hydration and dental care.

Tics and Movement

Stimulants can exacerbate pre-existing tics; levo-amphetamine is associated with more tics than dextro. In a tic-prone patient, favor dextro-dominant formulations and monitor; alpha-2 agonists are useful adjuncts.

Other

Headache, GI upset, overstimulation/"feeling wired," and, especially in children at higher doses, personality dampening ("zombification"), which is dose-dependent and should prompt a dose reduction. High doses also impair cognition (the inverted-U curve: low doses help attention and processing speed; high doses cause rigidity, perseveration, and worse cognitive flexibility).

Part 6: Overdose, Toxicity, and Boxed Warnings

Boxed Warnings

Acute Overdose

A sympathomimetic toxidrome:

• Cardiovascular: tachycardia, arrhythmia, hypertension, chest pain.
• CNS: agitation, tremor, hyperreflexia, seizures, hyperthermia.
• Psychiatric: psychosis, mania, aggression, panic.
• Severe cases: rhabdomyolysis, cardiovascular collapse.

Management is emergency care. Supportive: benzodiazepines are the mainstay for agitation, hypertension, and seizures; active cooling for hyperthermia; standard management of hypertensive emergency and arrhythmia. Do not deliberately acidify the urine to speed excretion, it risks precipitating rhabdomyolysis-related renal injury.

High-Dose and Long-Term Toxicity

• Neurotoxicity: dopaminergic terminal damage in animal models at high doses (≥60 mg/day-equivalent), more pronounced with amphetamines than methylphenidate.
• Long-term Parkinson's disease risk may be modestly elevated (on the order of a 1–2% absolute increase in some data), a reason, among others, to keep doses in the safe zone.
• High-dose psychiatric consequences (from narcolepsy patients dosed near 2× max): ~12× psychosis, ~3× psychiatric hospitalization, ~4× substance abuse, ~3× suicide-attempt risk. The ceiling exists for good reasons.

Abuse Potential in Perspective

Overall addiction risk from oral, prescribed use in a non-drug-seeking patient is roughly 1% or lower. Most true abuse is via intranasal or IV routes for euphoria, and immediate-release Adderall is the most preferred formulation for getting high. Extended-release lowers abuse liability; Vyvanse's prodrug design makes it essentially unabusable by non-oral routes.

Part 7: Drug Interactions

Absolute: MAOIs

Do not combine amphetamine with an MAOI, or start within 14 days of stopping one: risk of hypertensive crisis.

Urine/Stomach pH: The Big Pharmacokinetic Lever

Amphetamine handling is unusually pH-sensitive, and this cuts two ways:

• Absorption (gut): the notes flag stomach pH as one of the larger drug-food interactions in psychopharmacology. Practically, large fatty meals delay Adderall XR absorption by ~2.5 hours.
• Excretion (kidney): this is the clinically important one. Alkalinizing the urine (e.g., sodium bicarbonate, acetazolamide) reduces amphetamine clearance and raises/prolongs levels; acidifying the urine (e.g., ascorbic acid, ammonium chloride) increases clearance and shortens the effect. Be alert to agents and conditions that shift urinary pH.

CYP2D6

Amphetamine is a CYP2D6 substrate. Strong CYP2D6 inhibitors, bupropion, duloxetine, fluoxetine, paroxetine, can raise amphetamine exposure; watch for increased effect/side effects and consider a lower dose.

Serotonergic Agents

Combining with serotonergic drugs (SSRIs/SNRIs, and especially MAOIs) carries a theoretical serotonin syndrome risk. It's usually tolerable with SSRIs, but counsel patients and stay alert.

Clinically Useful Combinations

Part 8: Special Populations

Pregnancy

Human safety data are limited and imperfect. Amphetamine crosses the placenta; signals include modestly increased risk of low birth weight, preterm birth, and possible cardiac malformations, alongside neonatal effects (agitation, poor feeding). This is a shared decision: many patients with mild-to-moderate ADHD can pause the stimulant during pregnancy, while some with severe functional impairment reasonably continue after weighing risks with the patient and obstetrics. Use the lowest effective dose and coordinate care.

Lactation

Amphetamine is excreted into breast milk and reaches measurable infant levels; most guidance is cautious. If a patient chooses to breastfeed while taking it, use the lowest effective dose, prefer once-daily/shorter exposure, and monitor the infant for irritability, poor feeding, poor weight gain, and sleep disruption, in coordination with pediatrics.

Elderly

• Lower doses suffice and are safer. Typical effective doses run low, on the order of ~10 mg/day of amphetamine/dextroamphetamine (vs. ~30 mg/day methylphenidate).
• Older adults are more susceptible to cardiovascular and neurotoxic effects; brain amphetamine exposure runs higher at a given dose.
• Check a baseline ECG if any cardiac history, monitor BP closely, and generally avoid dosing above ~40 mg/day. For pure cognitive/energy augmentation in the medically ill elderly, low-dose methylphenidate is the better-studied stimulant.

Renal and Hepatic Impairment

Specific dosing guidance is limited. Amphetamine is partly renally excreted (and pH-dependent), so impaired renal function can raise exposure, reduce the dose and titrate cautiously with closer monitoring. In hepatic impairment, expect reduced metabolism and dose conservatively.

Children and Adolescents

• Methylphenidate is generally first-line under 18 (better tolerated, better response rates in children, less insomnia and appetite suppression). Reserve amphetamine for methylphenidate non-response or a clear prior amphetamine response.
• Start weight-based (~0.5 mg/kg/day amphetamine), titrate to effect, and track growth and weight.
• Behavioral scaffolding is not optional: parent training, school coordination, and structure amplify medication and sometimes replace the need for higher doses. Address classroom learning issues before escalating medication.
• Misuse and diversion risk rises around age 14–15, when adolescents can control their own dosing, count pills, watch refills, and educate against sharing/selling (a substantial minority of students with prescriptions are asked to divert).

Part 9: Discontinuation

Stopping amphetamine is not medically dangerous. There is no life-threatening withdrawal syndrome as there is with alcohol, benzodiazepines, or opioids.

What actually happens on stopping:

• After sustained daily use, patients may have days to a couple of weeks of fatigue, low motivation, and irritability, a dysphoric rebound, not physical danger and not addiction-like craving.
• The ADHD symptoms return, which can meaningfully impair work, family life, and driving.

How to stop:

• For low-to-moderate doses, an abrupt stop is medically fine, though many patients appreciate a brief taper to soften the rebound.
• For higher doses (>40–60 mg/day), taper by roughly 10 mg per month with monitoring.
• Supply-chain interruptions and formulation switches are common and safe medically, but leave patients symptomatic, plan bridges so patients aren't abruptly untreated.

Part 10: Adderall vs. the Alternatives

vs. Methylphenidate. The central choice. Amphetamines are modestly more effective, especially in adults; methylphenidate is better tolerated, safer across comorbidities, and less likely to trigger mania or psychosis, and is preferred in children. The default: methylphenidate first-line for safety, amphetamine when the patient has responded to or prefers it, or when methylphenidate underdelivers.

Adderall vs. Vyvanse (lisdexamfetamine). Same drug family, different delivery. Vyvanse gives the smoothest levels (fewer peaks/troughs, less crash), the lowest abuse potential (prodrug), immunity to food/pH/bariatric effects, and a longer duration, at meaningfully higher cost, and with about half of patients preferring it while half prefer to return to Adderall. Adderall XR is cheaper and effective but often needs a second daily dose despite the "XR" label.

Adderall vs. Mydayis. Mydayis extends coverage to ~16 hours for patients whose day runs long; otherwise incremental.

vs. Dexedrine / Zenzedi (100% dextro). Purer dextroamphetamine, useful when you want to minimize levo-driven cardiac effects and tics, or need fine dose granularity (Zenzedi's 7 strengths).

Avoid Evekeo (1:1 d:l) in most patients: more levo means more cardiac effect and more tics, with no efficacy advantage.

vs. Non-stimulants (atomoxetine, bupropion, alpha-2 agonists). Effect size ~0.45, roughly half that of stimulants. Reserve for stimulant failure/intolerance, substance-use concerns, or specific comorbidities (bupropion for depression/tobacco; guanfacine/clonidine for hypertension or tics).

Why is amphetamine sometimes over- and sometimes under-used? Diagnostic imprecision drives overprescribing at the front door; fear of controlled substances and community underdosing leave genuine responders undertreated. Both errors are solved by the same discipline: an honest diagnosis and dose-to-effect within the safe zone.

Mechanism: The Short Version

Amphetamine boosts dopamine and norepinephrine in the synapse by two mechanisms, which is what distinguishes it from methylphenidate:

1. Blocks the dopamine and norepinephrine reuptake transporters (like methylphenidate), keeping more neurotransmitter in the synapse; and
2. Reverses the transporters and displaces stored dopamine and norepinephrine out of the presynaptic terminal, actively releasing more into the synapse.

That second, releasing action explains amphetamine's slightly greater efficacy, and its greater rewarding/abuse potential, relative to methylphenidate, which only blocks reuptake.

Isomers matter. Dextroamphetamine is 2–4× more potent than levoamphetamine, with higher abuse potential, more appetite suppression, and shorter duration; levoamphetamine is longer-lasting but carries more cardiac side effects and more tics. Adderall's 3:1 d:l blend is the compromise; Dexedrine and Vyvanse are pure dextro.

Lisdexamfetamine (Vyvanse) is dextroamphetamine chemically tethered to L-lysine, an inactive prodrug that must be cleaved (in red blood cells) to release active drug at a rate-limited pace. That yields a smooth, plateau-like level, food/pH-independent absorption, and abuse resistance.

The clinical takeaway from the pharmacology: the effect follows an inverted-U: low-to-moderate doses sharpen attention and processing; excessive doses cause rigidity, perseveration, worse cognitive flexibility, and toxicity. More is not better past the effective dose.

The Bedside Cheat Sheet