Amphetamine sulfate is a central nervous system stimulant used to treat ADHD, narcolepsy, and in limited cases, obesity. It is a Schedule II controlled substance in the United States, meaning it has legitimate medical applications but carries a high potential for abuse and dependence. The drug is available as a generic tablet (typically 5 mg and 10 mg) and is also a component of well-known brand-name medications like Adderall.
How Amphetamine Sulfate Works
Amphetamine sulfate is the sulfate salt form of amphetamine, a synthetic compound first discovered in 1929 by biochemist Gordon Alles, who was searching for a substitute for ephedrine as a decongestant. The “sulfate” part refers to how the amphetamine molecule is paired with sulfuric acid to create a stable, water-soluble salt that the body can absorb when taken orally. Each unit of the salt contains two amphetamine molecules bound to one sulfate molecule.
The version used in standalone amphetamine sulfate tablets is racemic, meaning it contains equal amounts of two mirror-image forms of the molecule: d-amphetamine and l-amphetamine. Both forms stimulate the brain, but d-amphetamine is the more potent of the two. This matters because different medications use different ratios. Adderall, for example, contains four separate amphetamine salts (including amphetamine sulfate and dextroamphetamine sulfate) blended to deliver roughly 75% d-amphetamine and 25% l-amphetamine. Pure amphetamine sulfate delivers a 50/50 split.
In the brain, amphetamine increases the activity of certain chemical messengers that regulate attention, alertness, and motivation. It does this by prompting nerve cells to release more of these chemicals and by slowing their reabsorption, which keeps them active longer.
FDA-Approved Medical Uses
Amphetamine sulfate tablets are approved for three conditions:
- ADHD (Attention Deficit Disorder with Hyperactivity): It is used as part of a broader treatment plan that typically includes psychological, educational, and social support. It targets symptoms like distractibility, short attention span, hyperactivity, and impulsivity. It is not recommended for children under 3.
- Narcolepsy: A sleep disorder that causes overwhelming daytime drowsiness and sudden sleep episodes. Though narcolepsy rarely appears in children under 12, amphetamine sulfate can be used when it does.
- Obesity: Approved only as a short-term aid (a few weeks) for weight loss in patients who haven’t responded to other approaches like diet programs or other medications. Not approved for this use in children under 12.
Typical Dosing
For ADHD, children ages 3 to 5 typically start at 2.5 mg per day, with increases of 2.5 mg each week until the right balance is found. Children 6 and older start at 5 mg once or twice daily, increasing by 5 mg weekly. Total daily doses rarely need to exceed 40 mg.
For narcolepsy, the usual range is 5 to 60 mg per day, split into multiple doses. Children ages 6 to 12 start at 5 mg daily, while those 12 and older begin at 10 mg. Both groups can increase weekly until symptoms are controlled.
How Long It Stays in Your System
The two forms of amphetamine in the drug are eliminated at slightly different rates. In adults, d-amphetamine has an average half-life of about 10 hours, while l-amphetamine lingers a bit longer at around 13 hours. A “half-life” is the time it takes for half the drug to clear your bloodstream, so it generally takes four to five half-lives for the drug to be fully eliminated. That means amphetamine can remain detectable in the body for roughly two to three days after the last dose.
In children ages 6 to 12, elimination is somewhat faster: about 9 hours for d-amphetamine and 11 hours for l-amphetamine. The body breaks down amphetamine through several chemical pathways in the liver, producing a chain of byproducts that are eventually excreted.
Common Side Effects
The most frequently reported side effects are nervousness, headache, dry mouth, weight loss, nausea, and trouble sleeping. Changes in sex drive, constipation, diarrhea, and painful menstrual cramps also occur. Many of these are mild and may ease as the body adjusts to the medication.
Serious Risks
Amphetamine sulfate carries significant cardiovascular warnings. It can cause fast or irregular heartbeat, and in rare cases has been linked to sudden death, heart attack, or stroke, particularly in people with pre-existing heart defects or serious heart conditions. Symptoms like chest pain, shortness of breath, or fainting during treatment are considered emergencies.
Psychiatric side effects are also possible and can be severe. These include hallucinations, paranoia, mania, aggressive behavior, and new or worsening depression. Some people develop motor tics or teeth grinding. A cluster of symptoms involving high fever, confusion, rapid heartbeat, muscle stiffness, and loss of coordination can signal a dangerous reaction called serotonin syndrome, especially if the drug is combined with certain other medications.
Circulation problems can also develop, showing up as pale or bluish fingers or toes, numbness, tingling, or unexplained wounds on the extremities.
Amphetamine Sulfate vs. Mixed Amphetamine Salts
If you’ve heard of Adderall, you’ve already encountered amphetamine sulfate, but only as one piece of a four-salt blend. Adderall combines amphetamine sulfate, amphetamine aspartate, dextroamphetamine sulfate, and dextroamphetamine saccharate. This mix is designed to skew the ratio toward d-amphetamine, the more stimulating form, which is why Adderall’s effects can feel different from a pure amphetamine sulfate tablet.
Standalone amphetamine sulfate products include Evekeo and Evekeo ODT (an orally disintegrating tablet). Other brand-name amphetamine products like Dyanavel XR and Adzenys XR-ODT use extended-release formulations for longer-lasting effects throughout the day.
Legal Classification and Abuse Potential
The Drug Enforcement Administration classifies all amphetamine products as Schedule II controlled substances. This is the most restrictive category for drugs that still have accepted medical use. In practical terms, this means prescriptions cannot include refills. You need a new prescription each time, and many states impose additional limits on how early you can fill the next one.
The high abuse potential is not theoretical. Amphetamine’s history as a substance of misuse stretches back to the 1930s, when Smith, Kline and French marketed Benzedrine inhalers over the counter for congestion. By 1937, amphetamine sulfate tablets were approved for narcolepsy, Parkinsonism, and depression. The widespread availability fueled what public health historians have called America’s first amphetamine epidemic, lasting from 1929 through 1971. Modern scheduling and prescription requirements exist largely because of that history.