Adderall and Vyvanse are both amphetamine-based stimulant medications which are used to treat the symptoms of ADHD in both adolescents and adults. While they share many similarities, they also have a few key differences, which can affect how and why doctors use them in different circumstances. Read on to learn more about the similarities and differences in medical uses and effects.
Disclaimer: This post is not a recommendation or endorsement for Adderall or Vyvanse. These medications are only FDA-approved for the treatment of certain specific medical disorders, and can only be taken by prescription and with oversight from a licensed medical professional. We have written this post for informational purposes only, and our goal is solely to inform people about the science behind these drugs’ effects, mechanisms, and current approved medical uses.
What are Adderall and Vyvanse?
Adderall (dextroamphetamine-amphetamine) and Vyvanse (lisdexamfetamine) both belong to a class of drug called amphetamines.
Amphetamines act on the central nervous system (CNS) to increase levels of dopamine, norepinephrine, and serotonin [1, 2].
Adderall and Vyvanse are both stimulants that have been officially FDA-approved for the treatment of ADHD, as well as a few other medical conditions [1, 3, 4].
Adderall is also FDA-approved to treat the symptoms of narcolepsy and other fatigue-related conditions, such as excessive daytime sleepiness – whereas Vyvanse is also FDA-approved to treat binge eating disorders (BED) [5].
Stimulants such as Adderall and Vyvanse are often the “first-line”, or primary, treatments for ADHD [6, 7, 8].
American adults who take Adderall for ADHD have increased by 90% from 2002 to 2005. Vyvanse is not as commonly used and was approved for use in children in 2007, in adults in 2008, and in adolescents in 2010 [9, 10, 11].
However, amphetamine use can lead to addiction and abuse. Stimulants have become the second-most abused drug by college students. This stems from a belief that stimulants like Adderall are “harmless” (they are not) [1, 12, 13].
Both Adderall and Vyvanse are classified as Schedule II drugs by the FDA, meaning they pose a high risk of abuse that may lead to physical and/or psychological dependence. This also means that they require a prescription in order to be legally bought and used [1].
Components
While Adderall and Vyvanse are both amphetamine-based stimulants, they differ in their specific composition.
Adderall is composed of [14]:
- Dextroamphetamine (D-amphetamine) saccharate
- D-amphetamine sulfate
- Levoamphetamine (L-amphetamine) sulfate
- L-amphetamine aspartate
D- and L-amphetamine are chemically-identical mirror-images of each other. Adderall contains both molecules because the body processes each form differently, and combining these two forms together is believed to increase the strength or efficacy of the drug’s main effects [15, 16].
Vyvanse is only made up of lisdexamfetamine dimesylate. It is classified as a “prodrug” because it does not enter the body in its active form. Once inside the body, prodrugs are converted into their active forms. Vyvanse is converted to D-amphetamine, one of the components of Adderall [4].
Absorption Characteristics
The time to maximum concentration (Tmax) is the time it takes for a drug to reach maximum concentration in the blood. Theoretically, this is when drugs are believed to have their maximal effects. The Tmax for Vyvanse is 1 hour, whereas the Tmax for D-amphetamine (after conversion from lisdexamfetamine) is 3.5 hours [4].
However, according to one study (double-blind randomized controlled trial) of 50 children with ADHD, the Tmax of D-amphetamine (from lisdexamfetamine) was reported to be closer to 5 hours [17].
In the same study, the Tmax of D-amphetamine from extended-release Adderall (Adderall XR) was 6.6 hours. The Tmax values varied 3.5 times more for Adderall than Vyvanse. The fluctuating absorption characteristics of Adderall means that the effects of Vyvanse tend to be more predictable and easier to use by comparison [17, 18].
A few cell and animal studies have reported that Vyvanse is absorbed in the small intestine, and then converted to d-amphetamine by red blood cells. This conversion happens through a process called enzymatic hydrolysis, which is the breakdown of a molecule in the presence of water with the help of an enzyme or cofactor [4, 19].
Mechanisms of Action
Adderall and Vyvanse are both classified as nervous system stimulants, and each involves a number of different potential mechanisms to achieve these “stimulating” effects.
These stimulating effects can be roughly broken down into “physical” and “psychological” forms of stimulation.
On the “physical” side, both drugs act on mechanisms associated with physiological arousal. For example, both drugs are believed to cause the release of norepinephrine by stimulating α- and β-adrenergic receptors. Adrenergic receptors are those that specifically release neurotransmitters noradrenaline (also sometimes called adrenaline) [20, 21].
Stimulating the α-adrenergic receptor sites causes [20]:
- Constriction of blood vessels all over the body
Whereas stimulating the β-adrenergic receptor sites increases [20]:
- Heart rate
- Muscle blood flow
- The output of blood from the heart
These effects cause the body to be in a heightened state of physiological arousal, which generally results in increased perceived levels of physical energy [15].
However, the main “psychological” effects of these drugs stem from their effects on neurotransmitter levels and other mechanisms directly related to brain function.
For example, both Adderall and Vyvanse have D-amphetamine as their main active component, which acts by preventing a number of important neurotransmitters from being taken up, broken down, and stored inside neurons.
This is achieved by blocking the molecular “transporters” that bring neurotransmitters from the outside of the cell back into the inside of the cell. Specifically, D-amphetamine blocks [22, 4]:
- The dopamine reuptake transporter, resulting in increased dopamine activity throughout the brain
- The noradrenaline reuptake transporter, resulting in increased noradrenaline activity throughout the brain
D-amphetamine also prevents the storage of dopamine in compartments within the cell (synaptic vesicles). This increases the total amount of dopamine available to be used for cell-to-cell communication throughout the brain [2].
Finally, Adderall also inhibits the activity of proteins that break down dopamine, such as the enzymes monoamine oxidase A and -B (MAOA and MAOB). This further increases the amount of dopamine available for use in the brain [2].
Altogether, these individual effects combine together, greatly increasing the total activity of dopamine and other major neurotransmitters throughout the brain. This, in turn, is what is believed to be responsible for producing the primary “psychological” effects of these drugs.
According to one study of 16 healthy volunteers, D-amphetamine was twice as effective than L-amphetamine in causing feelings of euphoric mood, and in reducing depression symptoms [23].
However, there still may be some important distinctions between the effects of D- and L-amphetamine. For example, one animal study in rats reported that D-amphetamine may be better at improving overactivity and impulsiveness, whereas L-amphetamine may be more effective at improving sustained attention, specifically [24].
While more research (especially in human users) will be needed to fully tease out the subtle differences between the L- and D- forms of amphetamine, most of the general effects of Adderall and Vyvanse stem from similar mechanisms, and thus tend to have roughly identical effects in most patients.
In Summary
In general, these two medications are quite similar in their mechanisms and psychological effects. The main active component of both drugs is D-amphetamine, which acts on a number of different individual mechanisms to greatly increase dopamine activity throughout many regions of the brain.
The main difference between them is in how they are absorbed: Adderall is ingested in a form that is already biologically active, whereas Vyvanse is a “prodrug” that is only converted into active D-amphetamine gradually inside of the body.
This difference is important for two main reasons.
Firstly, it means that the effects of Vyvanse tend to be more consistent and longer-lasting, since the body converts it into its active form at a roughly constant rate, which results in a steady delivery of the active drug to the body and brain [25].
Secondly, these same features mean that Vyvanse is not as readily abusable as Adderall, since the conversion process from the “prodrug” to the “active” form happens at a steady rate, and therefore cannot be taken in large amounts to produce a rapid “high”. For this reason, Vyvanse is typically considered to be relatively safer, with lower abuse potential [26, 10, 25].
However, this difference is mostly important from a public health perspective: when each drug is taken as directed and prescribed by a doctor, their efficacy and safety are otherwise fairly similar.
1) Treating ADHD
Adderall is one of the most commonly-prescribed stimulants for ADHD. For example, one study of 154 children reported that Adderall was effective in 89% of children [27, 28].
Vyvanse is also widely-used, and has been reported to be effective in 74% of children with ADHD, based on a study of 52 children. This same study also tested Adderall, but only reported a 72% efficacy rate, suggesting that the two drugs may be roughly similar in their overall efficacy [17].
In the same study, both Adderall and Vyvanse were reported to treat ADHD significantly better than an inactive placebo. The patients’ scores on the SKAMP rating scale – a test used to measure ADHD symptoms in the classroom – were reported to be similar across patients who were treated with either Adderall or Vyvanse, suggesting similar overall therapeutic effects. Finally, the rates of negative side-effects were reported to be low for both treatment groups, suggesting that the two drugs may be roughly similar in terms of their overall safety [17].
However, there may still be some subtle differences between the two medications. For example, there is some evidence that Vyvanse may work in a slightly smaller number of patients, but produces greater improvements in ADHD symptoms. Conversely, Adderall has been reported to work in a greater overall proportion of patients, but may produce somewhat smaller improvements in ADHD symptoms. In other words, Vyvanse may improve symptoms better in some children, whereas Adderall may have a slightly wider range of efficacy [17].
Some researchers have suggested that these differences could be due to the mix of amphetamines in Adderall (both L- and D- forms of amphetamine), compared to just the one active form of amphetamine (D-amphetamine) that Vyvanse converts to [17].
Finally, there may also be some differences in their long-term efficacy in certain types of patients. For example, Adderall is typically only used for the short-term management of ADHD in adults, whereas its long-term use in adults and adolescents has not been proven to be helpful. However, Vyvanse has been shown to be effective long-term, at least according to one study of 349 adults with ADHD [27, 29, 4].
2) Increasing Focus
Most people that use Adderall or Vyvanse medically use it to increase focus due to conditions such as ADHD.
However, some researchers have proposed that Vyvanse may be more useful for adults in workplace settings, as the drug’s effects can last up to 14 hours with 1 dose while still being safe and tolerable [1, 4].
In contrast, the duration of Adderall’s effects is believed to be dependent on the specific formulation of Adderall taken (i.e. the extended release or instant release forms), but can potentially last up to 12 hours [30].
3) Reducing Impulsivity
ADHD is usually broken down into two subtypes: an “inattentive” type, and a “hyperactive-impulsive” type. People who are diagnosed with ADHD can have just one or the other, or both types (the “combined” type of ADHD) [31, 14].
Although it might sound counter-intuitive, the “stimulating” effects of amphetamines can actually reduce impulsivity, hyperactivity, and other related behaviors. This is because amphetamines specifically increase activity in regions of the brain believed to be involved in controlling attention and managing impulses [31, 14].
For example, one study of 287 adolescents reported that Adderall significantly improved hyperactivity/impulsivity symptoms in ADHD patients [31, 14].
According to another study of 18 children suffering from hyperactivity and aggression, Adderall decreased hyperactivity symptoms in 14 of the children [32].
4) Body Weight
Before amphetamines became one of the primary treatments for ADHD, they were formerly prescribed to help reduce weight by decreasing appetite.
However, this use is not officially approved by the FDA or other medical governing bodies.
Nonetheless, reductions in body weight can be a common side-effect of amphetamine-based medications. For example, one study has reported weight occurring in up to 9.2% to 21.9% of children prescribed Vyvanse [33, 26].
The effects of amphetamines on body weight may be due to their effects on the release of dopamine, norepinephrine, and serotonin – neurotransmitters which are believed to be heavily involved in regulating eating behaviors [34, 5, 35, 36].
These drugs’ effects on weight may also partially stem from their effects on counteracting impulsivity. For example, in a study of 259 adults with binge eating disorder (BED), 50 and 70 mg doses of Vyvanse were reported to lead to approximately 10.8 pounds’ worth of weight loss in BED patients – presumably due to reducing their impulses to binge-eat [5].
Similarly, a study of 56 ADHD patients given Adderall also reported weight loss due to decreased impulsivity when it comes to eating behavior [5].
Although Adderall-induced weight loss is usually not severe, it may lead to a significant loss of appetite. For example, one study of 584 children reported that significant appetite loss occurred in 21.9% of the children. Similarly, a study of 287 teens reported loss of appetite in 35.6% of treated patients [37, 38, 31].
5) Energy Levels
According to one study of 12 adults, D-amphetamine (the main active compound of both Vyvanse and Adderall) was reported to be significantly more effective than placebo at increasing subjective energy levels [39].
However, according to one animal study in rats, D-amphetamine was reported to decrease the production of the following molecular energy sources in the brain [40]:
- Glycogen
- Adenosine triphosphate (ATP)
- Guanosine triphosphate
- Phosphocreatine
Fatigue has also been reported to occur following withdrawal from amphetamine use, causing users to re-ingest amphetamine for increased energy [2].
Side Effects
Both Adderall and Vyvanse may have dangerous side effects and drug interactions. To learn about them, check out this post.
Different Uses of Adderall vs. Vyvanse
Although both medications are quite similar, there are still some key differences when it comes to how they are used by doctors, and which specific conditions they have been approved to treat.
Some applications of Adderall that have not been approved for Vyvanse include [41]:
- Narcolepsy
- ADHD-related hyperactivity
Narcolepsy is a disorder that causes extreme daytime drowsiness. A form of Adderall, Adderall XR, is often preferred by doctors, as it works for longer periods of time and has a slightly lower potential for abuse (compared to the instant-release forms of Adderall) [41].
Conversely, some uses of Vyvanse that have not been approved for Adderall include [42, 5]:
- Binge eating disorder (BED)
Vyvanse is the only medication approved by the U.S. Food and Drug Administration for binge eating disorder (BED). According to one study of 259 adults with BED, 70 mg of Vyvanse was reported to decrease binge eating episodes (from 4.6 per week to 0.5 per week) [5].
Relatedly, one animal study in rats reported that Vyvanse decreased binge-eating (of chocolate) by up to 71% [34].
Dosage
Note: The information in this section describes typical dose information for medical applications of Adderall and Vyvanse: it is not a guide to recreational or other non-medical use. Anyone taking these drugs by prescription should take care to follow the directions of their doctor as fully and accurately as possible to ensure optimal treatment.
The different doses of Adderall sold are 5 mg, 7.5 mg, 10 mg, 12.5 mg, 15 mg, 20 mg, and 30 mg. Many of these dosages are available in either an instant-release (IR) or extended-release (ER or XR) form, which affects how quickly they are released and absorbed by the body and brain [30, 43].
Because it is a prodrug, all forms of Vyvanse are considered “extended-release,” or long-acting [43].
Vyvanse comes in capsule form in 10 mg, 20 mg, 30 mg, 40 mg, 50 mg, 60 mg, and 70 mg doses. It is also available in a chewable tablet form for many of the lower doses.
According to one study in 18 healthy adult volunteers, taking Vyvanse in capsule form or as a solution did not significantly change the exposure to the drug. Eating food reportedly did not alter the exposure either, except for high-fat meals, which prolonged the drug’s effects by approximately one hour [4, 44].
Taking vitamin C or juices high in vitamin C may decrease the effectiveness of Adderall [30].
If a dose is missed but it is close to the time to take the next dose, then wait until then and take the dose. Otherwise, take the dose as soon as you remember. Do not “double-up” to account for a missed dose [30].
Limitations and Caveats
It is difficult to say for certain which stimulant is better: Adderall or Vyvanse. There are not many studies studying the two drugs in comparison. When compared, Adderall may better for some symptoms and situations, whereas Vyvanse may be better for some others [27, 28, 17].
However, the long-acting, slow-release of D-amphetamine from Vyvanse is believed to make it considerably safer, specifically due to a lower potential for abuse – so this can be an important fact for both doctors and patients to consider [26, 10, 25].
Furthermore, many of the clinical trials on these drugs have been performed on healthy people, which is not what one would see in regular practice. The limited number of long-term studies and the number of patients in the studies also make it difficult to find rare adverse events and side-effects [26].
Vyvanse has not been proven to be safe and effective for children ages 3 to 5, and so has only been FDA-approved for use in adolescents and adults [10].
Further Reading
Takeaway
Adderall and Vyvanse are both amphetamines which may be prescribed to treat ADHD. They are Schedule II controlled substances and should only ever be taken with a doctor’s prescription. The absorption speed and blood concentration of Adderall is more variable than Vyvanse, making Vyvanse the more predictable drug.
Both Adderall and Vyvanse increase focus, reduce impulsive behavior, reduce appetite, and increase subjective energy levels. Of the two, only Adderall is sometimes used to control narcolepsy, while only Vyvanse is under investigation for use in binge eating disorder.
