Speed is a street name for amphetamine, a powerful stimulant that speeds up signals between the brain and body. It typically appears as a white, grey, brown, or pink powder, though it also comes in pill form. People use it by swallowing, snorting, smoking, or injecting it. While amphetamines have legitimate medical uses for conditions like ADHD, the term “speed” almost always refers to the illicit, unregulated version sold on the street.
How Speed Affects the Brain
Amphetamine works by flooding the brain with two key chemical messengers: dopamine (which controls reward and pleasure) and norepinephrine (which controls alertness and the fight-or-flight response). Normally, after these chemicals do their job, they get recycled back into the nerve cell. Amphetamine disrupts that recycling process in two ways.
First, it enters the nerve cell through the same doorway dopamine uses to get back inside. Once there, it forces dopamine out of its storage compartments and back into the gap between nerve cells, where it keeps firing signals. Second, it physically reverses the direction of the transporter proteins that would normally pull dopamine back in, turning them into pumps that push dopamine out instead. The result is a massive surge of dopamine activity that the brain was never designed to handle, especially at recreational doses.
Recreational vs. Therapeutic Doses
This distinction matters because amphetamine exists in both worlds. Prescribed for ADHD, it produces blood levels of roughly 30 to 140 nanograms per milliliter, enough to improve focus without overwhelming the brain’s reward system. Recreational speed use produces blood levels of 500 to 2,500 nanograms per milliliter, roughly 10 to 18 times higher. That gap explains why prescribed amphetamine taken as directed carries a very different risk profile than street speed.
What Speed Feels Like
The immediate effects include a rush of euphoria, heightened alertness, a sense of confidence, and a sharp drop in appetite. Heart rate and blood pressure climb. Peak cardiovascular effects hit about 1 hour after ingestion, while changes in mood and behavior peak around the 2-hour mark. Body temperature rises, pupils dilate, and the mouth dries out. Many users feel restless or jittery, and the high can last several hours depending on the dose and how it was taken.
At higher doses, the picture shifts. Agitation, impulsiveness, aggression, and paranoia can set in. Some people experience chest pain, severe stomach pain, or seizures. Dangerously high body temperature is one of the most life-threatening complications and can lead to organ damage even before a person realizes they’re in trouble.
Signs of Overdose
Because street speed has no quality control, the line between a “normal” dose and an overdose is unpredictable. Warning signs include an irregular or racing heartbeat, difficulty breathing, chest pain, seizures, extreme agitation, and a very high body temperature. In severe cases, overdose can cause stroke, heart attack, kidney failure, or coma. If someone shows these symptoms after using speed, it’s a medical emergency.
What Happens When You Stop
Withdrawal symptoms typically begin within 24 hours of the last dose and unfold in two phases. The first is the “crash,” a period of intense fatigue, increased sleep, low mood, and strong cravings that usually resolves within about a week. After that comes a longer phase of lingering symptoms, including irritability, difficulty concentrating, and fluctuating mood, that generally takes around three weeks to clear. For heavy or long-term users, some symptoms can stretch beyond that timeline.
Long-term Damage From Chronic Use
Repeated use of speed at recreational levels can cause lasting changes to the brain. The dopamine system takes a direct hit. Prolonged heavy use reduces the brain’s ability to produce dopamine on its own, an impairment that can persist for months or even years after someone stops. Research in animals shows that chronic amphetamine and methamphetamine use can reduce the number of nerve fibers, destroy the connection points between neurons, and impair the normal functioning of both dopamine and serotonin systems.
The damage isn’t limited to the brain. Chronic use is associated with multiple heart problems, including high blood pressure, weakening of the heart muscle, and acute coronary events. Psychotic symptoms, particularly paranoia and hallucinations, can sometimes persist for months or years after use has stopped. Cognitive problems with attention, impulse control, working memory, and mental flexibility have been documented in long-term users, and for some, these deficits are slow to reverse.
Legal Classification
In the United States, amphetamines are classified as Schedule II controlled substances under the Controlled Substances Act. This means they’re recognized as having legitimate medical uses but carry a high potential for abuse and severe dependence. Prescription forms like Adderall and Dexedrine fall under this classification. Possessing or selling amphetamines without a prescription is a criminal offense in most countries.
How Long Speed Stays in Your System
Amphetamines are detectable in urine for 2 to 4 days after use. In oral fluid (saliva testing), the detection window is much shorter, typically 1 to 48 hours. Sweat patches can pick up the drug for 7 to 14 days. Hair testing has the longest window at up to 90 days, though it reflects use patterns over time rather than a single recent dose. These timelines can vary based on the amount used, frequency of use, metabolism, and body composition.