Stimulants (also known as psychostimulants; colloquially as "uppers") are a major class of psychoactive substances that increase activity of the nervous system to promote alertness, arousal, and motor activity. Stimulants represent one of the three major classes of psychoactive substances alongside depressants ("downers") and hallucinogens. Subjective effects can vary but generally include wakefulness, focus enhancement, appetite suppression, thought acceleration, ego inflation, and euphoria.
Since being discovered in the early 20th century, stimulants have been adopted throughout some parts of the world as prescription medicines for attention deficit hyperactivity disorder (ADHD), narcolepsy, and obesity. They have also gained widespread illicit use as recreational substances, despite the efforts of various governments.
Stimulants produce their effects through a number of pharmacological mechanisms, the most prominent of which are increasing concentrations of the neurotransmitters dopamine and norepinephrine by either promoting release (e.g. amphetamine, methamphetamine) or by blocking reuptake (e.g. cocaine, methylphenidate). Some stimulants also have an additional significant effect on serotonin, such as MDMA, MDA, and methylone; these substances are sometimes separately categorized and referred to as entactogens.
In addition to intended therapeutic use, many stimulants have significant abuse potential. They can also induce tolerance, psychological dependence, and possibly physical dependence (although not by the same mechanism(s) as opioids or depressants). The toxicity of stimulants can vary widely based on the individual properties of each chemical. It is strongly advised to use harm reduction practices when using these substances.
Stimulants include substances with various mechanisms of action that generally, but not necessarily, increase catecholaminergic transmission in the brain. Stimulants that work by directly modulating catecholaminergic signalling act as reuptake inhibitors (NDRIs, e.g. methylphenidate), releasing agents (NDRAs, e.g. amphetamine) or receptor ligands (e.g yohimbine). Stimulants that work by indirectly enhancing catecholaminergic signalling include adenosine antagonists (e.g. caffeine) and nicotine. Stimulants that work independently of catecholaminergic transmission include ampakines and convulsants (e.g. strychnine).
Disclaimer: The effects listed below cite the Subjective Effect Index (SEI), a literature based on anecdotal reports and the personal experiences of PsychonautWiki contributors. As a result, they should be treated with a healthy amount of skepticism. It is worth noting that these effects will not necessarily occur in a consistent or reliable manner, although higher doses are more likely to induce the full spectrum of effects. Likewise, adverse effects become much more likely with higher doses and may include serious injury or death. These effects are listed and defined in detail within their own dedicated articles below:
Alongside of these a variety of non-essential secondary effects are often present. These generally include but are not limited to:
- Focus enhancement
- Physical euphoria
- Cognitive euphoria
- Appetite suppression
- Memory enhancement
- Analysis enhancement
- Teeth grinding
- Increased music appreciation
- Ego inflation
- Pupil dilation
- Time distortion - This can be described as the experience of time speeding up and passing much quicker than it usually would when sober.
The effects which occur during the offset of a stimulant experience generally feel negative and uncomfortable in comparison to the effects which occurred during its peak. This is often referred to as a "comedown" and occurs because of neurotransmitter depletion. Its effects commonly include:
Experience reports can be found here:
The compounds listed below have been included on the basis of possessing varying degrees of stimulant effects. Some of them have a minimal stimulant effect while others may have a strong one. Many of these substances possess other qualities including entactogenic or nootropic effects.