240 effects across 7 categories
Subjective effects are the perceptual, cognitive, and physical experiences that occur under the influence of psychoactive substances. This index catalogs and describes these effects to support harm reduction, research, and informed decision-making.
Abnormal heartbeat (arrhythmia) is any deviation from the heart's normal rhythm — including beats that are too fast (tac...
Complex alterations in hunger, food preferences, and eating patterns that go beyond simple suppression or enhancement of...
A distinct increase in hunger and desire for food, often accompanied by enhanced enjoyment of taste and texture. Commonl...
A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete disinterest or even p...
Aching or tension in the back, commonly arising from sustained muscle tension, poor posture, or vasoconstriction during ...
Bodily control enhancement is the subjective feeling of improved physical precision, coordination, and dexterity — a sen...
A diffuse, heavy physical discomfort involving tension, pressure, and malaise in the torso and limbs, commonly reported ...
Body odour alteration is a distinct change in a person's natural scent that can occur when the body metabolizes certain ...
Brain zaps are sudden, brief, electrical shock-like sensations that originate in the head and sometimes radiate through ...
Bronchodilation is the widening of the bronchial airways in the lungs, reducing resistance to airflow and producing a su...
Changes in felt bodily form is the experience of one's body feeling as though it has altered its physical shape, structu...
A distortion of one's proprioceptive sense of gravity in which the perceived direction of gravitational pull shifts, til...
A slowing or cessation of bowel movements resulting in difficulty passing stool, commonly caused by opioid receptor acti...
A decreased desire and need to cough, medically known as antitussive action, which can also allow inhalation of larger a...
Decreased blood pressure (hypotension) is a drop in arterial blood pressure below normal levels, commonly produced by de...
Decreased heart rate (bradycardia) is a slowing of the heart's rhythm below the normal resting range of 60-100 beats per...
Decreased libido is a diminished interest in and desire for sexual activity, commonly caused by substances that suppress...
A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical discomfort, often cau...
Diarrhea is the occurrence of frequent, loose, or watery bowel movements as a side effect of certain psychoactive substa...
Difficulty urinating, also known as urinary retention, is the experience of being unable to easily pass urine despite a ...
A sensation of spinning, swaying, or lightheadedness that impairs balance and spatial orientation, often accompanied by ...
A persistent, uncomfortable reduction in saliva production causing the mouth and throat to feel parched, sticky, and dif...
Profuse perspiration exceeding normal thermoregulatory needs, common with stimulants and empathogens, contributing to de...
Involuntary, repeated yawning that occurs far more frequently than normal and often without the usual association with t...
Increased urinary frequency beyond normal patterns, caused by diuretic effects or bladder irritation from substances lik...
Gait alteration is a noticeable change in the way a person walks and moves through their environment, often producing a ...
A painful sensation of pressure, throbbing, or aching in the head that can range from a dull background discomfort to a ...
Increased blood pressure (hypertension) is an elevation of arterial pressure above the normal 120/80 mmHg baseline, comm...
Increased bodily temperature (hyperthermia) is an elevation of core body temperature above the normal 37C (98.6F) baseli...
A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a forceful, rapid poundi...
A marked enhancement of sexual desire, arousal, and sensitivity to erotic stimuli that can range from a gentle heighteni...
Increased phlegm production is the excessive generation of mucus in the throat and respiratory passages, leading to freq...
Increased salivation (hypersalivation or sialorrhea) is the excessive production of saliva beyond what can be comfortabl...
A persistent inability to fall asleep or maintain sleep despite physical tiredness, often characterized by a racing mind...
A persistent, diffuse urge to scratch the skin that arises without any external irritant, most commonly caused by opioid...
Spontaneous, uncontrollable, and often prolonged episodes of intense laughter that erupt without any identifiable cause ...
A distinct decrease in the ability to control one's physical body with precision, balance, and coordination, ranging fro...
Mouth numbing is a localized loss of sensation in the tongue, gums, cheeks, and surrounding oral tissues that occurs eit...
Muscle cramps are sudden, involuntary, and often painful contractions of muscles that occur as a side effect of certain ...
The experience of muscles throughout the body losing their rigidity and tension, becoming noticeably relaxed, loose, and...
Persistent partial contractions or tightening of muscles that produces uncomfortable stiffness, cramping, and low-level ...
Muscle twitching consists of small, involuntary, localized contractions or tremors within individual muscle groups — oft...
An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting, often occurring du...
Nausea suppression is the pharmacological reduction or elimination of nausea and the urge to vomit, achieved through sub...
Rapid, involuntary oscillating movements of the eyes that cause vision to vibrate and blur, often making it difficult to...
Orgasm suppression (anorgasmia) is the difficulty or complete inability to achieve orgasm despite adequate sexual stimul...
A suppression of negative physical sensations such as aches and pains, ranging from dulled awareness of discomfort to co...
Perception of bodily heaviness is the subjective feeling that one's body has become dramatically heavier, resulting in m...
Perception of bodily lightness is the subjective feeling that one's body has become dramatically lighter — sometimes nea...
An abnormal physical intolerance and sensitivity to light that causes discomfort, squinting, or pain in the eyes, typica...
Physical autonomy is the experience of one's body performing actions — from simple tasks like walking to complex sequenc...
A perceptual distancing from one's own physical body that ranges from a subtle sense of numbness or detachment to a prof...
An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity, or a full-body org...
Physical fatigue is a state of bodily exhaustion characterized by reduced energy, diminished capacity for physical activ...
A visible narrowing of the pupil diameter (miosis) that reduces the size of the dark center of the eye to a small pinpoi...
A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to dramatic saucer-like expa...
A dangerous slowing and shallowing of breathing that can progress from barely noticeable reductions in respiratory rate ...
Restless legs is an uncomfortable neurological effect characterized by an irresistible compulsion to move the legs (and ...
Excessive nasal discharge commonly occurring during opioid withdrawal or from nasal irritation caused by insufflated sub...
A state of deep physical and mental calming that manifests as a progressive desire to remain still, lie down, and eventu...
Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threatening medical emerg...
Seizure suppression is the pharmacological reduction or prevention of seizures through substances that dampen excessive ...
Serotonin syndrome is a potentially fatal medical emergency caused by excessive serotonergic activity in the central and...
Visible reddening of the skin due to vasodilation, most prominent on the face and chest, commonly caused by alcohol and ...
Spatial disorientation is the inability to accurately perceive one's position or orientation within the surrounding envi...
Spontaneous physical movements are involuntary, seemingly random yet patterned body movements — twitches, swaying, gestu...
Stamina enhancement is an increase in one's ability to sustain physical and mental exertion over extended periods withou...
A state of heightened physical and mental energy characterized by increased wakefulness, elevated motivation, and a subj...
Stomach bloating is the uncomfortable distension of the abdomen resulting from gas accumulation, fluid retention, or gas...
Stomach cramps are sharp, intermittent pains in the abdominal region that can occur when psychoactive substances irritat...
Teeth chattering is an involuntary, rhythmic movement of the jaw that produces rapid clicking or chattering of the teeth...
An involuntary clenching and rhythmic grinding of the jaw muscles, known clinically as bruxism, that produces a compulsi...
Impaired thermoregulation causing unpredictable fluctuations between feeling hot and cold, with risk of hyperthermia or ...
Temporary erectile dysfunction is the substance-induced inability to achieve or sustain a penile erection sufficient for...
Phantom perception of ringing, buzzing, or hissing in the ears without external sound source, potentially caused or wors...
Involuntary rhythmic shaking of the hands, limbs, or body, ranging from fine tremor to gross shaking, common with stimul...
A narrowing of blood vessels throughout the body that produces sensations of cold extremities, tingling in the fingers a...
Vasodilation is the relaxation and widening of blood vessels, leading to increased blood flow, reduced blood pressure, a...
Vibrating vision is the subjective experience of the visual field rapidly oscillating or shaking due to involuntary eye ...
Excessive tear production causing overflow tearing and blurred vision, commonly occurring during opioid withdrawal and w...
Addiction suppression is the experience of a marked decrease in or complete cessation of the cravings, compulsive urges,...
A complete or partial inability to form new memories or recall existing ones during and after substance use, ranging fro...
A perceived improvement in one's ability to logically deconstruct concepts, recognize patterns, and reach novel conclusi...
Analysis suppression is a cognitive impairment in which the capacity for logical reasoning, critical evaluation, and sys...
Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to overwhelming panic ...
A partial to complete suppression of anxiety and general unease, producing a calm, relaxed mental state free from worry....
Autonomous voice communication is the experience of hearing and engaging in conversation with one or more internal voice...
A powerful emotional release and cleansing involving the surfacing, processing, and resolution of deeply held feelings, ...
Cognitive disconnection is the experience of feeling profoundly detached from one's own thoughts, sense of identity, and...
A cognitive and emotional state of intense dissatisfaction, discomfort, and malaise encompassing feelings of depression,...
A cognitive and emotional state of intense well-being, elation, happiness, and joy that manifests as a profound mental c...
Mental exhaustion and difficulty sustaining thought after intense cognitive experiences, common during substance comedow...
An overwhelming, difficult-to-resist urge to continuously take more of a substance in order to maintain or intensify its...
A shift in the nature of thought from verbal, linear sentence structures to intuitive, non-linguistic concepts that are ...
An impairment of abstract thinking marked by a persistent inability to grasp or comprehend concepts and situations that ...
An increase in the ability to imagine new ideas, overcome creative blocks, think about existing concepts in novel ways, ...
Creativity suppression is a decrease in both the motivation and the cognitive capacity for creative output — manifesting...
Reduced ability to evaluate risks, weigh options, and make sound judgments, particularly insidious because the individua...
Intense, often prolonged sensation of having already experienced the current moment, common with psychedelics and dissoc...
Delirium is a serious and potentially dangerous state of acute mental confusion involving disorientation, incoherent tho...
A delusion is a fixed, false belief that is held with unshakeable certainty and is impervious to contradicting evidence ...
A detachment from one's own sense of self, body, or mental processes, as if observing oneself from outside or feeling th...
A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasure in activities, oft...
Depression reduction is the experience of a meaningful and often lasting decrease in depressive symptoms — including low...
A perceptual disturbance in which the external world feels profoundly unreal, dreamlike, or artificially constructed, as...
A marked reduction in social inhibitions, self-consciousness, and behavioral restraint that manifests as increased openn...
Enhanced dream vividness, complexity, and recall, often occurring as REM rebound after discontinuing REM-suppressing sub...
Dream suppression is a decrease in the intensity, frequency, and recollection of dreams — ranging from dreams becoming v...
Grandiose overconfidence and inflated self-importance, opposite of ego death, commonly produced by stimulants and associ...
Ego replacement is the experience of one's usual personality and sense of self being completely overtaken by an entirely...
Reduced capacity to experience the full range of emotions, resulting in flattened affect, commonly associated with chron...
A dramatic amplification of emotional responses in which feelings — whether positive or negative — become significantly ...
A blunting or flattening of emotional experience in which feelings become muted, distant, or seemingly absent. The indiv...
A state of intensified compassion and emotional openness in which one feels deeply connected to others, motivated by gen...
Enhancement and suppression cycles is a distinctive cognitive effect in which the mind alternates between periods of not...
Feelings of impending doom is the sudden onset of an overwhelming, visceral certainty that something terrible is about t...
An enhanced ability to direct and sustain attention on a single task or stimulus with unusual clarity and persistence, o...
Focus suppression is a diminished capacity to direct and sustain attention on a chosen target — a task, a thought, a con...
Glossolalia is the experience of spontaneously speaking or thinking in patterns of syllables that sound and feel like a ...
A heightened capacity to become fully absorbed and engrossed in external media such as music, films, video games, and ar...
A general amplification of one's sensitivity to finding things humorous and amusing, often causing previously unremarkab...
An enhanced state of self-reflective awareness in which one feels drawn to examine their own thoughts, emotions, behavio...
Irritability is a sustained state of emotional reactivity in which the threshold for annoyance, frustration, and anger i...
Jamais vu is the unsettling experience of encountering something deeply familiar — a word, a place, a person, one's own ...
A diminished ability to formulate, comprehend, or articulate language, ranging from difficulty finding the right words t...
Abnormally elevated mood, energy, and activity with impulsive behavior and grandiosity, associated with stimulant use an...
Memory enhancement is a state of improved mnemonic function in which past memories become unusually accessible, vivid, a...
A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ranging from mild fo...
Mindfulness in the substance context refers to a state of heightened present-moment awareness in which attention is full...
Mixed emotions is a state in which several conflicting emotional states are experienced simultaneously rather than seque...
A heightened sense of drive, ambition, and willingness to accomplish tasks, making productive effort feel rewarding and ...
Motivation suppression is a state of diminished drive and willingness to engage in goal-directed behavior — from everyda...
The experience of having more than one internal narrative or stream of consciousness simultaneously occurring, each proc...
A profound enhancement of one's enjoyment and emotional connection to music, making songs feel deeply meaningful and rev...
Intensified nostalgic feelings with enhanced emotional vividness of memories, producing deep longing and appreciation fo...
A feeling of increased fascination, awe, and childlike wonder attributed to everyday concepts, objects, and experiences,...
A panic attack is a discrete episode of acute, overwhelming fear or terror that arises suddenly and peaks within minutes...
Irrational suspicion and belief that others are watching, plotting against, or intending harm toward oneself, ranging fr...
A decrease in the personal, cultural, and cognitive biases through which one normally filters their perception, enabling...
Personality regression is a state in which a person temporarily adopts the cognitive patterns, emotional responses, spee...
Personal meaning enhancement is a state in which everyday events, coincidences, song lyrics, environmental details, and ...
Psychosis is a serious psychiatric state involving a fundamental break from consensus reality — characterized by firmly ...
A renewed sense of physical vitality, mental freshness, and emotional restoration that can emerge during or after a subs...
Sensed presence is the vivid and often unshakeable feeling that an unseen conscious being — whether benevolent, malevole...
A progressive onset of drowsiness, heaviness, and the desire to sleep that pulls the individual toward rest with increas...
Heightened receptivity to external suggestions, ideas, and influence, commonly experienced during psychedelic and hypnot...
Suggestibility suppression is a state of heightened skepticism and resistance to external influence in which a person be...
Suicidal ideation is the emergence of thoughts, urges, or preoccupations centered on ending one's own life — ranging fro...
The experience of thoughts occurring at a dramatically increased rate, as if the mind has been shifted into a higher gea...
A state in which disparate thoughts, concepts, and ideas become fluidly and spontaneously interconnected, revealing patt...
The experience of thoughts occurring at a markedly reduced pace, as if the mind has been placed into slow motion. Intern...
Thought disorganization is a cognitive impairment in which the normal capacity for structured, sequential, and logical t...
Becoming trapped in a repeating cycle of thoughts, actions, and emotions that loops every few seconds to minutes. Short-...
Enhanced ability to structure, categorize, and systematize thoughts and ideas, common with low-dose stimulants and some ...
Subjective perception of time becomes dramatically altered — minutes may feel like hours, or hours pass in moments. Can ...
An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation in that it does not ...
A visual phenomenon in which a faint, ghostly imprint of a previously viewed image persists in the visual field after th...
The perception of contact with seemingly sentient, independently acting beings that appear within hallucinatory states. ...
Perceived increase or decrease in environmental brightness beyond actual illumination levels, common with stimulants and...
A visual distortion in which the colors reflected from object surfaces split into distinct, offset layers — most commonl...
An intensification of the brightness, vividness, and saturation of colors in the external environment, making the world ...
A visual phenomenon in which the colors of objects or the entire visual field are statically replaced with alternative h...
The visual experience of colors on objects and surfaces cycling through continuous, fluid transformations, shifting from...
A visual effect in which the perceived saturation and vibrancy of colors is diminished, causing the environment to appea...
Alterations in how the distance of objects within the visual field is perceived, causing layers of scenery to appear exa...
The experience of seeing rainbow-like spectrums of color and prismatic halos embedded within bright light sources and re...
The visual experience of seeing a single object as two separate, overlapping images, similar to crossing one's eyes, ran...
The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow, breathe, melt, or s...
A visual distortion in which the environment and objects within it appear fragmented into geometric, cube-like facets, a...
A visual effect in which existing textures and surfaces — carpets, clouds, foliage, walls — spontaneously reorganize int...
A visual hallucination that manifests within the external environment as though it were physically real, ranging from su...
A distortion in the apparent breadth or shape of one's visual field, ranging from an expanded, panoramic sensation to a ...
Perception of visual motion as choppy discrete frames rather than smooth continuous flow, resembling low-FPS video, most...
The experience of perceiving complex, ever-shifting geometric patterns superimposed over the visual field or visible beh...
Vivid, detailed visual experiences perceived within an imagined mental landscape that can only be seen with closed eyes,...
A visual distortion in which objects appear larger or closer than they actually are, as though one's visual field has be...
A hallucinatory effect in which stationary objects in the environment appear to spontaneously move, animate, or behave a...
A visual effect in which objects in the environment appear to warp, stretch, melt, or animate autonomously, often return...
An increased ability and tendency to perceive meaningful patterns, faces, and images within ambiguous or random visual s...
Alterations in side vision ranging from enhanced peripheral awareness to tunnel vision, with character varying by substa...
Distortion of perceived depth, distance, and size of real objects, making things appear closer, further, larger, or smal...
A hallucinatory phenomenon in which the observer's visual perspective shifts from the normal first-person viewpoint to a...
The visual field begins to repeat and nest within itself in a self-similar, fractal-like manner, as if reality is being ...
The visual field fractures into distinct, cleanly cut sections that slowly drift apart from their original positions bef...
The perceived environment in which hallucinatory experiences take place, ranging from recognizable locations drawn from ...
The perception of dark, humanoid silhouettes lurking in peripheral vision or standing in direct line of sight, appearing...
Textures appear to mirror and tessellate across surfaces in intricate, self-similar symmetrical patterns that maintain d...
Surfaces and textures progressively smooth and simplify until the environment takes on the fluid, stylized appearance of...
Moving objects leave visible trails of varying length and opacity behind them, similar to long-exposure photography. Tra...
Objects and scenery undergo perceived visual metamorphosis, smoothly shapeshifting into other recognizable forms over se...
A deeply distressing hallucinatory state involving sustained exposure to nightmarish, terrifying, and personally threate...
Vision becomes sharper and more defined than normal, as though a slightly blurry lens has been brought into perfect focu...
Vision becomes blurred, indistinct, and out of focus, as though looking through a smudged lens. Fine details degrade and...
A dissociative visual-cognitive effect in which the observer can physically see objects with normal or near-normal clari...
Halos or glowing fields of light appear to surround objects, people, and light sources. These luminous borders shimmer w...
A dissociative visual effect involving a progressive detachment from visual perception, ranging from minor suppression a...
A high-level hallucinatory state in which the observer perceives masses of complex, innately readable geometric forms th...
A high-level hallucinatory state in which the observer perceives a vast, interconnected web of geometric representations...
A sudden and disorienting visual distortion in which the entire visual field appears to be rotated, mirrored, or flipped...
A translucent fog or haze overlays the visual field, softening the environment and reducing clarity. May appear colorles...
A visual effect in which the brain appears to process visual information at an accelerated rate, causing fast-moving obj...
Persistent static-like visual noise across the visual field resembling television snow, which can persist after psychede...
A visual distortion in which the perceived visual field is elongated or compressed along one axis, stretching horizontal...
A visual effect consisting of rapid, rhythmic flashes of light across the visual field, resembling a strobe light, most ...
A visual distortion in which portions of the visual field appear to curl, spiral, or rotate around a central axis, rangi...
Auditory distortion is the experience of sounds becoming warped, pitch-shifted, flanged, or otherwise altered in their p...
Auditory enhancement is a heightened sensitivity and appreciation of sound in which music, voices, and ambient noise bec...
Auditory hallucination is the perception of sounds that have no external source — hearing music, voices, environmental n...
Auditory misinterpretation is the brief, spontaneous misidentification of real sounds as entirely different sounds — amb...
A dampening of auditory perception in which sounds become muffled, distant, and reduced in both volume and clarity, as t...
Unprompted physical sensations that arise without external touch or stimulus, manifesting as tingling, buzzing, warmth, ...
Tactile distortion is the warping of existing touch and body sensations — textures may feel alien, pressure may register...
The sense of touch becomes dramatically heightened, making physical contact feel intensely pleasurable and detailed. Tex...
Tactile hallucinations are convincing physical sensations experienced without any corresponding external stimulus — phan...
A progressive decrease in the ability to feel physical touch, ranging from mild numbness to complete bodily anaesthesia....
Anticipatory response is a Pavlovian conditioning phenomenon in which the body begins mimicking a substance's effects — ...
Component controllability is the unusual and often exhilarating experience of being able to consciously direct, modify, ...
Dosage independent intensity is the uncommon and poorly understood phenomenon in which a person experiences effects far ...
Gustatory enhancement is the experience of tastes becoming significantly more vivid, nuanced, and pleasurable (or, in so...
Gustatory hallucinations are phantom taste experiences in which distinct flavors manifest in the mouth without any corre...
Gustatory suppression is the diminishment or elimination of taste perception, rendering food and drink bland, flavorless...
Machinescapes are complex multisensory hallucinations involving the perception of enormous mechanical landscapes built f...
Memory replays are vivid, multisensory re-experiences of past events that go far beyond normal recall — the person doesn...
Olfactory enhancement (hyperosmia) is the experience of smells becoming dramatically more vivid, nuanced, and perceptibl...
Olfactory hallucinations (phantosmia) involve the perception of convincing phantom smells — pleasant, foul, or utterly s...
Olfactory suppression (hyposmia or anosmia) is the diminishment or complete loss of smell perception, rendering previous...
Scenarios and plots are the narrative structures that emerge within hallucinatory states — coherent or surreal storyline...
An overwhelming flood of sensory information that exceeds the brain's ability to process, creating a chaotic cascade of ...
Stimulation of one sense triggers involuntary experiences in another — seeing sounds as colors, tasting textures, or hea...
Profound subjective experience of dying, including life review, acceptance, and dissolution, distinct from ego death in ...
Progressive blurring and dissolution of the boundary between self and external reality, merging one's sense of identity ...
A profound dissolution of the sense of self in which personal identity, memories, and the boundary between self and worl...
Perception of encountering autonomous beings or presences during psychedelic states, ranging from vague presences to ful...
A sudden, visceral realization of the profound significance and improbability of one's own existence as a conscious bein...
The experience that all moments across the timeline of existence are equally real and simultaneously occurring, fundamen...
Perception of interdependent opposites is the profound, felt realization that reality is structured around complementary...
Perception of predeterminism is the powerful subjective experience of feeling — not merely thinking, but viscerally know...
Perception of self-design is the powerful and often paradoxical feeling that one has personally authored, designed, or c...
A profound intensification of spiritual feelings, mystical awareness, and a sense of sacred connection to something grea...
A profound sense that identity extends beyond the self to encompass other people, nature, or all of existence. Boundarie...
