Amphetamine/dextroamphetamine is a prescription stimulant most commonly known by the brand name Adderall. It works by raising levels of dopamine and norepinephrine in the brain, and it is primarily prescribed for attention-deficit/hyperactivity disorder (ADHD) and narcolepsy. While the medication is well-studied and effective for those conditions, it carries a range of side effects and risks that shift depending on how it is used, how long someone takes it, and whether the person taking it actually has ADHD in the first place.
How It Works in the Brain
The drug is a mixture of amphetamine salts, combining two mirror-image forms of the amphetamine molecule: dextroamphetamine (the “right-handed” form) and levoamphetamine (the “left-handed” form). In most commercial formulations, dextroamphetamine makes up a larger share because it tends to have stronger effects on attention and focus, though both forms contribute to the overall clinical response. In clinical trials comparing the two, both outperformed placebo, and while dextroamphetamine showed a slight edge, the difference between the two was not large enough to reach statistical significance.1PubMed. Levoamphetamine vs dextroamphetamine in minimal brain dysfunction. Replication, time response, and differential effect by diagnostic group and family rating
At the molecular level, the drug increases dopamine and norepinephrine in the spaces between neurons by blocking the transporters that normally vacuum those chemicals back into the cell. It also reverses the direction of those transporters, effectively pumping dopamine out instead of pulling it in. On top of that, it slows the breakdown of these brain chemicals by interfering with the enzyme that normally degrades them inside the neuron.2PubMed Central. The Pharmacology of Amphetamine and Methylphenidate: Relevance to the Neurobiology of Attention-Deficit/Hyperactivity Disorder and Other Psychiatric Comorbidities – Section: Preclinical Studies The net result is a flood of dopamine and norepinephrine in key brain circuits, which sharpens focus, raises motivation, and increases alertness.
What It Is Prescribed For
ADHD is the primary reason doctors prescribe amphetamine/dextroamphetamine. Clinical studies have consistently shown that it reduces the core symptoms of ADHD, including inattention, hyperactivity, and impulsivity. In head-to-head comparisons with methylphenidate (the active ingredient in Ritalin and Concerta), amphetamine-based stimulants performed at least as well, with some studies showing stronger improvements on teacher and clinician ratings.3Journal of Child and Adolescent Psychopharmacology. Efficacy of Adderall and methylphenidate in attention deficit hyperactivity disorder: A reanalysis using drug-placebo and drug-drug response curve methodology Both amphetamine-based and methylphenidate-based drugs are considered first-line treatments, and published comparisons support acceptable safety profiles for both.4PubMed Central. Amfetamine and methylphenidate medications for attention-deficit/hyperactivity disorder: complementary treatment options
Beyond symptom control, a meta-analysis found that stimulant medications also improve quality of life in people with ADHD, though the effect on quality-of-life measures is somewhat smaller than the effect on core symptom ratings.5PubMed. Systematic Review and Meta-Analysis: Effects of Pharmacological Treatment for Attention-Deficit/Hyperactivity Disorder on Quality of Life This matters because ADHD affects relationships, work performance, and emotional regulation in ways that go well beyond the checklist of diagnostic symptoms.
The second approved use is for narcolepsy and related conditions that cause severe daytime sleepiness. Amphetamines have been used for this purpose for decades. A clinical review of excessive daytime sleepiness lists amphetamines alongside wakefulness-promoting agents like modafinil as primary treatments for central disorders of hypersomnolence, with behavioral strategies as a useful add-on.6PubMed. Excessive Daytime Sleepiness: A Clinical Review In practice, newer medications have taken over as initial choices for many narcolepsy patients, but amphetamines remain an important option when other drugs are insufficient.
Common Side Effects
Most people who take amphetamine/dextroamphetamine at prescribed doses notice at least a few side effects, especially in the first weeks. The most frequently reported include:
- Appetite loss: Stimulants blunt hunger, sometimes substantially. This is one of the most reliable effects and often the most bothersome for patients, especially children.
- Insomnia: Because the drug promotes wakefulness, taking it too late in the day or using a long-acting formulation can make it hard to fall asleep.
- Dry mouth: A common autonomic side effect that tends to persist as long as the medication is active.
- Increased heart rate and blood pressure: Stimulants activate the sympathetic nervous system, reliably raising resting heart rate and blood pressure by modest amounts in most users.
- Jitteriness or anxiety: Some people feel overstimulated, particularly at higher doses or early in treatment.
Many of these side effects are dose-dependent and subside or become tolerable after the first few weeks. However, appetite suppression and sleep disruption tend to persist for as long as someone takes the medication, and managing them often involves adjusting the dose, timing, or formulation.
Cardiovascular Risks
The heart-related effects of amphetamine/dextroamphetamine generate more clinical concern than any other category of risk. At prescribed doses, the drug reliably raises heart rate and blood pressure. For most healthy young adults, these increases are modest and not dangerous. The worry intensifies in adults, particularly those with preexisting heart conditions, because there has been concern that stimulant medications could raise the risk of serious cardiovascular events like heart attacks, strokes, arrhythmias, and sudden death.7PubMed Central. Adult ADHD Medications and Their Cardiovascular Implications
The evidence on rare events is mixed. Large population studies have generally not found a dramatic increase in heart attacks or strokes among people taking prescribed stimulants, but these studies have limited power to detect small increases in very rare events. What is clear is that blood pressure and heart rate elevations are real and consistent, so anyone with hypertension, structural heart disease, or a history of arrhythmia needs careful monitoring. Prescribers typically check blood pressure and pulse at baseline and periodically during treatment, and may avoid stimulants altogether in patients with certain cardiac conditions.
Psychiatric Side Effects
Stimulant-induced psychosis is rare at therapeutic doses, but it does happen, and it has been documented across age groups. An analysis of 49 randomized controlled trials in children found that psychotic or manic symptoms occurred at a rate of about 1.5 per 100 person-years of treatment, with no comparable events in the placebo groups. In roughly nine out of ten of the post-marketing cases reviewed, the patient had no prior psychiatric history. Hallucinations in children often had a distinctive character: seeing or feeling insects, snakes, or worms on the skin.8Pediatrics. Hallucinations and Other Psychotic Symptoms Associated With the Use of Attention-Deficit/Hyperactivity Disorder Drugs in Children
The risk climbs sharply when the drug is taken above prescribed doses. A case report described a 29-year-old man with ADHD who took more than his recommended dose of Adderall and developed persistent psychotic symptoms that required treatment with an antipsychotic medication.9PubMed Central. Adderall-Induced Persistent Psychotic Disorder Managed With Long-Acting Injectable Haloperidol Decanoate This underscores a consistent theme in the literature: the psychiatric risks of amphetamines are heavily dose-dependent, and misuse dramatically changes the risk profile compared with guideline-based prescribing.
The “Study Drug” Myth
Amphetamine/dextroamphetamine is one of the most commonly misused prescription drugs on college campuses. Estimates suggest that up to one in five college students have used prescription stimulants non-medically at some point, most often by taking pills that were not prescribed to them.10PubMed Central. Raising Awareness About Prescription and Stimulant Abuse in College Students Through On-Campus Community Involvement Projects A national survey found that past-year non-medical use among college students averaged about four percent overall but ranged from zero to 25 percent depending on the school, with rates higher at colleges with more competitive admissions, among fraternity and sorority members, and among students with lower GPAs.11PubMed. Non-medical use of prescription stimulants among US college students: prevalence and correlates from a national survey
The motivation behind this misuse is almost always the same: people believe the drug will make them smarter, sharper, or more productive. The evidence does not support this belief. A pilot study of healthy college students found that Adderall had minimal effects on cognitive performance while producing large effects on mood and subjective feelings of being “activated.” On one measure of attention, performance improved slightly, but working memory actually got worse. Participants could not reliably tell whether the drug had helped their performance.12PubMed Central. Neurocognitive, Autonomic, and Mood Effects of Adderall: A Pilot Study of Healthy College Students
A separate study confirmed this disconnect. Healthy participants given mixed amphetamine salts showed no overall cognitive enhancement, yet they believed their performance was better on the drug than on placebo. The authors found a possible exception: participants who started with lower cognitive ability may have seen small benefits on a handful of tasks, but for most people, the perceived boost was an illusion.13PubMed. Objective and subjective cognitive enhancing effects of mixed amphetamine salts in healthy people This is an important finding because it means the drug’s main effect in non-ADHD users is to make them feel like they are performing better, which is a powerful reinforcer for continued use even when it is not actually helping.
Misuse Patterns and Diversion
Non-medical use does not just mean taking a friend’s pill before an exam. Among college students with ADHD prescriptions, about 40 percent endorsed at least one form of misuse, including taking more than prescribed, intentionally combining the medication with alcohol or other drugs, or giving or selling pills to others. Diversion of prescribed stimulants was reported by more than a third of those with prescriptions, and those who misused their own medication were much more likely to also binge drink and use other substances.14PubMed Central. Misuse of prescribed stimulant medication for ADHD and associated patterns of substance use: preliminary analysis among college students
This pattern of co-use matters clinically. Combining amphetamines with alcohol, for instance, can mask the sedating effects of alcohol, leading people to drink more than they otherwise would. The stimulant does not make alcohol less toxic; it just makes the person feel less drunk. And the association between stimulant misuse and other substance use suggests that for a subset of users, stimulant misuse is part of a broader pattern of risky drug behavior rather than an isolated academic shortcut.
Addiction and Dependence
Amphetamines are a Schedule II controlled substance in the United States, the same classification as oxycodone and fentanyl, reflecting both their medical utility and their potential for abuse. All drugs that can cause addiction share a common pathway: they increase dopamine signaling in a brain region called the nucleus accumbens, the hub of the brain’s reward circuit.15PubMed Central. Addiction and brain reward and antireward pathways With chronic exposure at high doses, the brain recalibrates its reward system. Dopamine release during drug use progressively recruits other brain regions involved in motivation, decision-making, and memory, embedding drug-related cues deeply into neural circuits that drive craving and compulsive use.16PubMed Central. Neurobiologic processes in drug reward and addiction
At prescribed therapeutic doses, genuine addiction is uncommon, though physical dependence (meaning the body adjusts to the drug’s presence and withdrawal symptoms occur when it is stopped) can develop even in people who use the medication exactly as directed. The distinction between dependence and addiction matters: dependence is a predictable physiological adaptation, while addiction involves compulsive drug-seeking behavior and loss of control over use. Most patients who take prescribed stimulants develop some degree of dependence but do not develop the pattern of escalating use, craving, and life disruption that characterizes addiction.
Tolerance Over Time
A common question among long-term users is whether the drug stops working. Laboratory studies confirm that the brain does adapt to repeated stimulant exposure. In animal models, chronic treatment leads to an upregulation of dopamine transporters, meaning the brain manufactures more of the molecular machinery that clears dopamine from synapses, partially countering the drug’s effect. PET imaging in medication-naive adults with ADHD showed a roughly 24 percent increase in dopamine transporter availability in key brain regions after a year of treatment.17PubMed Central. Tolerance to Stimulant Medication for Attention Deficit Hyperactivity Disorder: Literature Review and Case Report
Here is the twist: despite measurable changes in brain chemistry, clinical symptom control was maintained throughout that same year. Pharmacological tolerance (changes at the receptor level) and clinical tolerance (the drug stops helping) are not always the same thing. Many people take the same dose of amphetamine for years and continue to benefit. Others do notice fading effectiveness and need dose adjustments. The researchers who documented the transporter changes speculated that the upregulation might worsen symptoms during the hours when the drug is not active, rather than undermining its effect during the hours when it is working. Practically speaking, tolerance is real at the biological level, but its clinical impact varies widely from person to person.
What Withdrawal Looks Like
Stopping amphetamines after regular use typically produces a recognizable set of symptoms: low mood, fatigue, increased appetite, excessive sleep, and difficulty experiencing pleasure. These symptoms are thought to reflect a state of relative dopamine depletion in the brain during the period when the reward system is readjusting.18Biological Psychiatry. The effects of lisuride on mood and sleep during acute withdrawal in stimulant abusers: A preliminary report
Early descriptions of stimulant withdrawal proposed a three-phase model: an initial “crash” phase with exhaustion and depression, followed by a longer withdrawal period with fluctuating mood and cravings, and finally an extinction phase. However, controlled inpatient studies have not consistently confirmed a distinct crash phase. Instead, mood tends to improve gradually over weeks.19PubMed. Stimulant withdrawal Amphetamine withdrawal is generally less physically dramatic than withdrawal from alcohol or opioids. There are no seizures or life-threatening complications. But the psychological symptoms, especially the flatness, fatigue, and inability to feel motivated, can be quite distressing and are a major driver of relapse in people with stimulant use disorders.
Pregnancy Risks
Decisions about stimulant use during pregnancy involve weighing the consequences of untreated ADHD against potential harm to the developing fetus. The evidence here is still evolving and, in some areas, conflicting. One study of birth defects found that early-pregnancy use of ADHD medications was associated with roughly three times the odds of gastroschisis, a serious abdominal wall defect in newborns, even after adjusting for maternal age.20PubMed Central. ADHD Medication Use During Pregnancy and Risk for Selected Birth Defects: National Birth Defects Prevention Study, 1998–2011
For complications in later pregnancy, the picture depends on whether stimulant use continues past the first trimester. A large matched-cohort study found that first-trimester-only exposure was actually associated with a lower risk of preterm birth and spontaneous abortion compared with no exposure at all. But when use continued into the second or third trimester, risks rose for pre-eclampsia, placental abruption, preterm birth, and smaller-than-expected babies. When researchers directly compared women who continued stimulants to those who stopped after the first trimester, the continuation group had roughly three and a half times the risk of stillbirth and nearly double the risk of preterm birth.21PubMed. Prescription Stimulant Continuation in Pregnancy and Birth Outcomes A separate study of pregnant women on prescription stimulants confirmed the elevated risk for pre-eclampsia and found that continuation into the second half of pregnancy was associated with a 30 percent higher risk of preterm birth compared with discontinuation.22PubMed Central. Placental Complications Associated With Psychostimulant Use in Pregnancy
These findings do not mean that every pregnant person should immediately stop their medication. Untreated ADHD during pregnancy can itself lead to problems: poor prenatal care adherence, impulsive decisions, accidents, and worsening of coexisting conditions like anxiety or depression. The conversation between patient and prescriber should weigh the specific person’s symptom severity, the availability of non-stimulant alternatives, and the gestational timing of any planned changes.
Growth Effects in Children
Parents often worry that stimulants will stunt their child’s growth, and this concern is not unfounded. Children with ADHD who take stimulants do tend to be slightly shorter than their peers. However, research complicates the simple narrative that the drug is the cause. A large study from Sweden found that children with ADHD were more likely to be shorter than average both before and after stimulant medications became widely available in the country. The association with shorter height was present in a cohort born before stimulants were introduced and was similar in magnitude to the association seen in a cohort born after.23PubMed. Associations Between Attention-Deficit/Hyperactivity Disorder (ADHD), ADHD Medication, and Shorter Height: A Quasi-Experimental and Family-Based Study This suggests that ADHD itself may be associated with shorter stature, independent of medication effects. Stimulant-related appetite suppression could contribute to growth slowing during treatment, but the idea that the drug permanently reduces adult height is not strongly supported by the available evidence.
How Genetics and Urine Chemistry Affect Response
Not everyone responds to the same dose in the same way, and genetics is one reason. Amphetamine is partly broken down by a liver enzyme called CYP2D6, and people carry different versions of the gene that codes for it. A study of children and adolescents found that those genetically predicted to be “poor metabolizers” (meaning their version of the enzyme works slowly, so the drug lingers in the body longer) had significantly higher odds of reporting symptom improvement compared with intermediate metabolizers. Interestingly, there was no corresponding increase in side effects among the poor metabolizers.24PubMed. Effect of CYP2D6 genetic variation on patient-reported symptom improvement and side effects among children and adolescents treated with amphetamines Pharmacogenomic testing is not yet routine for stimulant prescribing, but these findings hint at why the same dose can be transformative for one person and inadequate for another.
Urine chemistry also matters. Amphetamine is a weak base, and its excretion by the kidneys depends heavily on urine pH. When urine is acidic, more of the drug is excreted and its effects are shorter-lived. When urine is alkaline, the drug is reabsorbed back into the bloodstream and its effects last longer.25PubMed. Influences of urinary pH on the pharmacokinetics of three amphetamine-type stimulants using a new high-performance liquid chromatographic method Modeling studies have confirmed that these shifts are large enough to be clinically meaningful.26PubMed Central. Mechanistic PBPK Modeling of Urine pH Effect on Renal and Systemic Disposition of Methamphetamine and Amphetamine This has practical implications: medications or supplements that significantly change urine pH (antacids, vitamin C in large doses, certain urinary alkalinizers) can alter how long amphetamine stays in your system, potentially intensifying or weakening its effects without any change in the dose you took.
Neurotoxicity at High Doses
At therapeutic doses, amphetamine is not thought to cause lasting brain damage. At high recreational or binge-pattern doses, the story changes. Animal studies and research on heavy users have identified multiple overlapping mechanisms of harm, including oxidative stress (an imbalance between damaging free radicals and the brain’s ability to neutralize them), inflammation in brain tissue, overactivation of nerve cells to the point of damage, and dysfunction of the cellular machinery that produces energy and recycles damaged proteins.27PubMed Central. Amphetamine toxicities: classical and emerging mechanisms The practical takeaway is straightforward: the margin between a therapeutic dose and a neurotoxic dose is not trivially small, but it is also not infinite. Recreational users who take large amounts, binge for days, or combine amphetamines with other stimulants are exposing their brains to a fundamentally different pharmacological reality than someone taking a prescribed dose once a day.