Subjective Effect Index
138 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.
physical
43Appetite changes
Complex alterations in hunger, food preferences, and eating patterns that go beyond simple suppression or enhancement of...
0 substancesphysicalneutralcommon
Appetite enhancement
A distinct increase in hunger and desire for food, often accompanied by enhanced enjoyment of taste and texture. Commonl...
20 substancesphysicaldose-dependentneutral
Appetite suppression
A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete disinterest or even p...
127 substancesphysicalstimulantempathogen
Back pain
Aching or tension in the back, commonly arising from sustained muscle tension, poor posture, or vasoconstriction during ...
1 substancephysicaladversecommon
Body load
A diffuse, heavy physical discomfort involving tension, pressure, and malaise in the torso and limbs, commonly reported ...
53 substancesphysicaladversedose-dependent
Changes in felt gravity
A distortion of one's proprioceptive sense of gravity in which the perceived direction of gravitational pull shifts, til...
22 substancesphysicaldose-dependentneutral
Constipation
A slowing or cessation of bowel movements resulting in difficulty passing stool, commonly caused by opioid receptor acti...
32 substancesphysicaldose-dependentneutral
Cough suppression
A decreased desire and need to cough, medically known as antitussive action, which can also allow inhalation of larger a...
16 substancesphysicaldose-dependentneutral
Dehydration
A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical discomfort, often cau...
144 substancesphysicaladversestimulant
Dizziness
A sensation of spinning, swaying, or lightheadedness that impairs balance and spatial orientation, often accompanied by ...
85 substancesphysicaldose-dependentneutral
Dry mouth
A persistent, uncomfortable reduction in saliva production causing the mouth and throat to feel parched, sticky, and dif...
77 substancesphysicaldose-dependentneutral
Excessive sweating
Profuse perspiration exceeding normal thermoregulatory needs, common with stimulants and empathogens, contributing to de...
3 substancesphysicaladversedose-dependent
Excessive yawning
Involuntary, repeated yawning that occurs far more frequently than normal and often without the usual association with t...
37 substancesphysicaldose-dependentneutral
Frequent urination
Increased urinary frequency beyond normal patterns, caused by diuretic effects or bladder irritation from substances lik...
41 substancesphysicaladversedose-dependent
Headache
A painful sensation of pressure, throbbing, or aching in the head that can range from a dull background discomfort to a ...
82 substancesphysicaldose-dependentadverse
Increased heart rate
A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a forceful, rapid poundi...
199 substancesphysicalcardiovascularcommon
Increased libido
A marked enhancement of sexual desire, arousal, and sensitivity to erotic stimuli that can range from a gentle heighteni...
98 substancesphysicaldose-dependentneutral
Insomnia
A persistent inability to fall asleep or maintain sleep despite physical tiredness, often characterized by a racing mind...
71 substancesphysicaldose-dependentneutral
Itchiness
A persistent, diffuse urge to scratch the skin that arises without any external irritant, most commonly caused by opioid...
17 substancesphysicaldose-dependentneutral
Laughter fits
Spontaneous, uncontrollable, and often prolonged episodes of intense laughter that erupt without any identifiable cause ...
40 substancesphysicaldose-dependentneutral
Motor control loss
A distinct decrease in the ability to control one's physical body with precision, balance, and coordination, ranging fro...
91 substancesphysicaldose-dependentneutral
Muscle relaxation
The experience of muscles throughout the body losing their rigidity and tension, becoming noticeably relaxed, loose, and...
62 substancesphysicaldose-dependentneutral
Muscle tension
Persistent partial contractions or tightening of muscles that produces uncomfortable stiffness, cramping, and low-level ...
36 substancesphysicaladversecommon
Nausea
An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting, often occurring du...
237 substancesphysicaladversecommon
Nystagmus
Rapid, involuntary oscillating movements of the eyes that cause vision to vibrate and blur, often making it difficult to...
24 substancesphysicaldose-dependentneutral
Pain relief
A suppression of negative physical sensations such as aches and pains, ranging from dulled awareness of discomfort to co...
79 substancesphysicaldose-dependentadverse
Photophobia
An abnormal physical intolerance and sensitivity to light that causes discomfort, squinting, or pain in the eyes, typica...
10 substancesphysicaldose-dependentneutral
Physical disconnection
A perceptual distancing from one's own physical body that ranges from a subtle sense of numbness or detachment to a prof...
6 substancesphysicaldose-dependentneutral
Physical euphoria
An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity, or a full-body org...
166 substancesphysicalemotionalpositive
Pupil constriction
A visible narrowing of the pupil diameter (miosis) that reduces the size of the dark center of the eye to a small pinpoi...
26 substancesphysicaldose-dependentneutral
Pupil dilation
A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to dramatic saucer-like expa...
121 substancesphysicalcommonpsychedelic
Respiratory depression
A dangerous slowing and shallowing of breathing that can progress from barely noticeable reductions in respiratory rate ...
115 substancesphysicaladverseserious
Runny nose
Excessive nasal discharge commonly occurring during opioid withdrawal or from nasal irritation caused by insufflated sub...
9 substancesphysicaladversewithdrawal
Sedation
A state of deep physical and mental calming that manifests as a progressive desire to remain still, lie down, and eventu...
186 substancesphysicalcognitivedepressant
Seizure
Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threatening medical emerg...
151 substancesphysicaldangerousmedical-emergency
Skin flushing
Visible reddening of the skin due to vasodilation, most prominent on the face and chest, commonly caused by alcohol and ...
7 substancesphysicalneutralcommon
Stimulation
A state of heightened physical and mental energy characterized by increased wakefulness, elevated motivation, and a subj...
236 substancesphysicalcognitivestimulant
Teeth grinding
An involuntary clenching and rhythmic grinding of the jaw muscles, known clinically as bruxism, that produces a compulsi...
91 substancesphysicalstimulantempathogen
Temperature regulation disruption
Impaired thermoregulation causing unpredictable fluctuations between feeling hot and cold, with risk of hyperthermia or ...
0 substancesphysicaladversedangerous
Tinnitus
Phantom perception of ringing, buzzing, or hissing in the ears without external sound source, potentially caused or wors...
7 substancesphysicaladverseototoxic
Tremors
Involuntary rhythmic shaking of the hands, limbs, or body, ranging from fine tremor to gross shaking, common with stimul...
15 substancesphysicaladversedose-dependent
Vasoconstriction
A narrowing of blood vessels throughout the body that produces sensations of cold extremities, tingling in the fingers a...
107 substancesphysicalcardiovascularadverse
Watery eyes
Excessive tear production causing overflow tearing and blurred vision, commonly occurring during opioid withdrawal and w...
17 substancesphysicaladversewithdrawal
cognitive
48Amnesia
A complete or partial inability to form new memories or recall existing ones during and after substance use, ranging fro...
117 substancescognitivedose-dependentset-and-setting-dependent
Analysis enhancement
A perceived improvement in one's ability to logically deconstruct concepts, recognize patterns, and reach novel conclusi...
98 substancescognitivedose-dependentset-and-setting-dependent
Anxiety
Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to overwhelming panic ...
282 substancescognitiveemotionaladverse
Anxiety suppression
A partial to complete suppression of anxiety and general unease, producing a calm, relaxed mental state free from worry....
134 substancescognitivedose-dependentset-and-setting-dependent
Catharsis
A powerful emotional release and cleansing involving the surfacing, processing, and resolution of deeply held feelings, ...
11 substancescognitivedose-dependentset-and-setting-dependent
Cognitive dysphoria
A cognitive and emotional state of intense dissatisfaction, discomfort, and malaise encompassing feelings of depression,...
16 substancescognitivedose-dependentset-and-setting-dependent
Cognitive euphoria
A cognitive and emotional state of intense well-being, elation, happiness, and joy that manifests as a profound mental c...
127 substancescognitiveemotionalpositive
Cognitive fatigue
Mental exhaustion and difficulty sustaining thought after intense cognitive experiences, common during substance comedow...
55 substancescognitiveadversecomedown
Compulsive redosing
An overwhelming, difficult-to-resist urge to continuously take more of a substance in order to maintain or intensify its...
100 substancescognitivedose-dependentset-and-setting-dependent
Conceptual thinking
A shift in the nature of thought from verbal, linear sentence structures to intuitive, non-linguistic concepts that are ...
100 substancescognitivedose-dependentset-and-setting-dependent
Confusion
An impairment of abstract thinking marked by a persistent inability to grasp or comprehend concepts and situations that ...
115 substancescognitivedose-dependentset-and-setting-dependent
Creativity enhancement
An increase in the ability to imagine new ideas, overcome creative blocks, think about existing concepts in novel ways, ...
48 substancescognitivedose-dependentset-and-setting-dependent
Decision-making impairment
Reduced ability to evaluate risks, weigh options, and make sound judgments, particularly insidious because the individua...
1 substancecognitiveadversedangerous
Deja vu
Intense, often prolonged sensation of having already experienced the current moment, common with psychedelics and dissoc...
0 substancescognitiveneutralpsychedelic
Depersonalization
A detachment from one's own sense of self, body, or mental processes, as if observing oneself from outside or feeling th...
40 substancescognitivedissociativeadverse
Depression
A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasure in activities, oft...
182 substancescognitivedose-dependentset-and-setting-dependent
Derealization
A perceptual disturbance in which the external world feels profoundly unreal, dreamlike, or artificially constructed, as...
36 substancescognitivedissociativeperceptual
Disinhibition
A marked reduction in social inhibitions, self-consciousness, and behavioral restraint that manifests as increased openn...
95 substancescognitivedose-dependentset-and-setting-dependent
Dream potentiation
Enhanced dream vividness, complexity, and recall, often occurring as REM rebound after discontinuing REM-suppressing sub...
67 substancescognitiveneutralpositive
Ego inflation
Grandiose overconfidence and inflated self-importance, opposite of ego death, commonly produced by stimulants and associ...
32 substancescognitiveadversestimulant
Emotion intensification
A dramatic amplification of emotional responses in which feelings — whether positive or negative — become significantly ...
8 substancescognitivedose-dependentset-and-setting-dependent
Emotion suppression
A blunting or flattening of emotional experience in which feelings become muted, distant, or seemingly absent. The indiv...
34 substancescognitivedose-dependentset-and-setting-dependent
Emotional blunting
Reduced capacity to experience the full range of emotions, resulting in flattened affect, commonly associated with chron...
9 substancescognitiveadversechronic
Empathy enhancement
A state of intensified compassion and emotional openness in which one feels deeply connected to others, motivated by gen...
48 substancescognitiveemotionalsocial
Focus enhancement
An enhanced ability to direct and sustain attention on a single task or stimulus with unusual clarity and persistence, o...
64 substancescognitivedose-dependentset-and-setting-dependent
Immersion enhancement
A heightened capacity to become fully absorbed and engrossed in external media such as music, films, video games, and ar...
111 substancescognitiveperceptualpositive
Increased sense of humor
A general amplification of one's sensitivity to finding things humorous and amusing, often causing previously unremarkab...
46 substancescognitivedose-dependentset-and-setting-dependent
Introspection
An enhanced state of self-reflective awareness in which one feels drawn to examine their own thoughts, emotions, behavio...
84 substancescognitivedose-dependentset-and-setting-dependent
Language suppression
A diminished ability to formulate, comprehend, or articulate language, ranging from difficulty finding the right words t...
29 substancescognitivedose-dependentset-and-setting-dependent
Mania
Abnormally elevated mood, energy, and activity with impulsive behavior and grandiosity, associated with stimulant use an...
62 substancescognitivedangerousstimulant
Memory suppression
A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ranging from mild fo...
112 substancescognitivecommondepressant
Motivation enhancement
A heightened sense of drive, ambition, and willingness to accomplish tasks, making productive effort feel rewarding and ...
64 substancescognitivedose-dependentset-and-setting-dependent
Multiple thought streams
The experience of having more than one internal narrative or stream of consciousness simultaneously occurring, each proc...
13 substancescognitivedose-dependentset-and-setting-dependent
Music appreciation enhancement
A profound enhancement of one's enjoyment and emotional connection to music, making songs feel deeply meaningful and rev...
17 substancescognitivedose-dependentset-and-setting-dependent
Nostalgia enhancement
Intensified nostalgic feelings with enhanced emotional vividness of memories, producing deep longing and appreciation fo...
0 substancescognitivepositiveemotional
Novelty enhancement
A feeling of increased fascination, awe, and childlike wonder attributed to everyday concepts, objects, and experiences,...
83 substancescognitiveperceptualpositive
Paranoia
Irrational suspicion and belief that others are watching, plotting against, or intending harm toward oneself, ranging fr...
106 substancescognitiveadversecommon
Personal bias suppression
A decrease in the personal, cultural, and cognitive biases through which one normally filters their perception, enabling...
66 substancescognitivedose-dependentset-and-setting-dependent
Rejuvenation
A renewed sense of physical vitality, mental freshness, and emotional restoration that can emerge during or after a subs...
16 substancescognitivedose-dependentset-and-setting-dependent
Sleepiness
A progressive onset of drowsiness, heaviness, and the desire to sleep that pulls the individual toward rest with increas...
52 substancescognitivedose-dependentset-and-setting-dependent
Suggestibility enhancement
Heightened receptivity to external suggestions, ideas, and influence, commonly experienced during psychedelic and hypnot...
17 substancescognitiveneutraltherapeutic
Thought acceleration
The experience of thoughts occurring at a dramatically increased rate, as if the mind has been shifted into a higher gea...
115 substancescognitivestimulantpsychedelic
Thought connectivity
A state in which disparate thoughts, concepts, and ideas become fluidly and spontaneously interconnected, revealing patt...
56 substancescognitivedose-dependentset-and-setting-dependent
Thought deceleration
The experience of thoughts occurring at a markedly reduced pace, as if the mind has been placed into slow motion. Intern...
119 substancescognitivedose-dependentset-and-setting-dependent
Thought loops
Becoming trapped in a repeating cycle of thoughts, actions, and emotions that loops every few seconds to minutes. Short-...
86 substancescognitivepsychedeliccannabis
Thought organization
Enhanced ability to structure, categorize, and systematize thoughts and ideas, common with low-dose stimulants and some ...
18 substancescognitivepositivetherapeutic
Time distortion
Subjective perception of time becomes dramatically altered — minutes may feel like hours, or hours pass in moments. Can ...
133 substancescognitiveperceptualcommon
Wakefulness
An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation in that it does not ...
157 substancescognitivephysicalstimulant
visual
30After images
A visual phenomenon in which a faint, ghostly imprint of a previously viewed image persists in the visual field after th...
69 substancesvisualpsychedelicdose-dependent
Autonomous entity
The perception of contact with seemingly sentient, independently acting beings that appear within hallucinatory states. ...
9 substancesvisualpsychedelicdose-dependent
Brightness alteration
Perceived increase or decrease in environmental brightness beyond actual illumination levels, common with stimulants and...
40 substancesvisualperceptualdose-dependent
Colour enhancement
An intensification of the brightness, vividness, and saturation of colors in the external environment, making the world ...
97 substancesvisualpsychedelicdose-dependent
Colour shifting
The visual experience of colors on objects and surfaces cycling through continuous, fluid transformations, shifting from...
71 substancesvisualpsychedelicdose-dependent
Depth perception distortions
Alterations in how the distance of objects within the visual field is perceived, causing layers of scenery to appear exa...
53 substancesvisualpsychedelicdose-dependent
Diffraction
The experience of seeing rainbow-like spectrums of color and prismatic halos embedded within bright light sources and re...
39 substancesvisualpsychedelicdose-dependent
Double vision
The visual experience of seeing a single object as two separate, overlapping images, similar to crossing one's eyes, ran...
46 substancesvisualpsychedelicdose-dependent
Drifting
The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow, breathe, melt, or s...
117 substancesvisualpsychedelicdose-dependent
Environmental cubism
A visual distortion in which the environment and objects within it appear fragmented into geometric, cube-like facets, a...
21 substancesvisualpsychedelicdose-dependent
Frame rate suppression
Perception of visual motion as choppy discrete frames rather than smooth continuous flow, resembling low-FPS video, most...
25 substancesvisualperceptualdissociative
Geometry
The experience of perceiving complex, ever-shifting geometric patterns superimposed over the visual field or visible beh...
139 substancesvisualpsychedelicdose-dependent
Internal hallucination
Vivid, detailed visual experiences perceived within an imagined mental landscape that can only be seen with closed eyes,...
103 substancesvisualpsychedelicdose-dependent
Magnification
A visual distortion in which objects appear larger or closer than they actually are, as though one's visual field has be...
15 substancesvisualpsychedelicdose-dependent
Pattern recognition enhancement
An increased ability and tendency to perceive meaningful patterns, faces, and images within ambiguous or random visual s...
78 substancescognitivevisualpsychedelic
Peripheral vision changes
Alterations in side vision ranging from enhanced peripheral awareness to tunnel vision, with character varying by substa...
0 substancesvisualperceptualdose-dependent
Perspective distortions
Distortion of perceived depth, distance, and size of real objects, making things appear closer, further, larger, or smal...
56 substancesvisualperceptualpsychedelic
Recursion
The visual field begins to repeat and nest within itself in a self-similar, fractal-like manner, as if reality is being ...
23 substancesvisualpsychedelicdose-dependent
Scenery slicing
The visual field fractures into distinct, cleanly cut sections that slowly drift apart from their original positions bef...
57 substancesvisualpsychedelicdose-dependent
Settings, sceneries, and landscapes
The perceived environment in which hallucinatory experiences take place, ranging from recognizable locations drawn from ...
95 substancesvisualpsychedelicdose-dependent
Shadow people
The perception of dark, humanoid silhouettes lurking in peripheral vision or standing in direct line of sight, appearing...
13 substancesvisualpsychedelicdose-dependent
Symmetrical texture repetition
Textures appear to mirror and tessellate across surfaces in intricate, self-similar symmetrical patterns that maintain d...
77 substancesvisualpsychedelicdose-dependent
Texture liquidation
Surfaces and textures progressively smooth and simplify until the environment takes on the fluid, stylized appearance of...
3 substancesvisualpsychedelicdose-dependent
Tracers
Moving objects leave visible trails of varying length and opacity behind them, similar to long-exposure photography. Tra...
91 substancesvisualpsychedelicdose-dependent
Transformations
Objects and scenery undergo perceived visual metamorphosis, smoothly shapeshifting into other recognizable forms over se...
84 substancesvisualpsychedelicdose-dependent
Visual acuity enhancement
Vision becomes sharper and more defined than normal, as though a slightly blurry lens has been brought into perfect focu...
80 substancesvisualpsychedelicdose-dependent
Visual acuity suppression
Vision becomes blurred, indistinct, and out of focus, as though looking through a smudged lens. Fine details degrade and...
44 substancesvisualpsychedelicdose-dependent
Visual auras
Halos or glowing fields of light appear to surround objects, people, and light sources. These luminous borders shimmer w...
3 substancesvisualpsychedelicdose-dependent
Visual haze
A translucent fog or haze overlays the visual field, softening the environment and reducing clarity. May appear colorles...
16 substancesvisualpsychedelicdose-dependent
Visual snow
Persistent static-like visual noise across the visual field resembling television snow, which can persist after psychede...
1 substancevisualadversepotentially-permanent
auditory
4Auditory distortion
Auditory distortion is the experience of sounds becoming warped, pitch-shifted, flanged, or otherwise altered in their p...
52 substancesauditoryperceptualdose-dependent
Auditory enhancement
Auditory enhancement is a heightened sensitivity and appreciation of sound in which music, voices, and ambient noise bec...
47 substancesauditoryperceptualdose-dependent
Auditory hallucination
Auditory hallucination is the perception of sounds that have no external source — hearing music, voices, environmental n...
41 substancesauditoryperceptualdose-dependent
Auditory suppression
A dampening of auditory perception in which sounds become muffled, distant, and reduced in both volume and clarity, as t...
13 substancesauditoryperceptualdose-dependent
tactile
3Spontaneous tactile sensations
Unprompted physical sensations that arise without external touch or stimulus, manifesting as tingling, buzzing, warmth, ...
12 substancestactilesomatosensorydose-dependent
Tactile enhancement
The sense of touch becomes dramatically heightened, making physical contact feel intensely pleasurable and detailed. Tex...
87 substancestactilesensorypositive
Tactile suppression
A progressive decrease in the ability to feel physical touch, ranging from mild numbness to complete bodily anaesthesia....
28 substancestactilesomatosensorydose-dependent
multisensory
2Sensory overload
An overwhelming flood of sensory information that exceeds the brain's ability to process, creating a chaotic cascade of ...
7 substancesmultisensoryperceptualpsychedelic
Synaesthesia
Stimulation of one sense triggers involuntary experiences in another — seeing sounds as colors, tasting textures, or hea...
50 substancesmultisensoryperceptualpsychedelic
transpersonal
8Death simulation
Profound subjective experience of dying, including life review, acceptance, and dissolution, distinct from ego death in ...
0 substancestranspersonalpsychedelic5-MeO-DMT
Dissolution of boundaries
Progressive blurring and dissolution of the boundary between self and external reality, merging one's sense of identity ...
0 substancestranspersonalpsychedelicmystical
Ego death
A profound dissolution of the sense of self in which personal identity, memories, and the boundary between self and worl...
97 substancescognitivetranspersonalpsychedelic
Entity contact
Perception of encountering autonomous beings or presences during psychedelic states, ranging from vague presences to ful...
8 substancestranspersonalpsychedelicDMT
Existential self-realization
A sudden, visceral realization of the profound significance and improbability of one's own existence as a conscious bein...
64 substancestranspersonalmysticalpsychedelic
Perception of eternalism
The experience that all moments across the timeline of existence are equally real and simultaneously occurring, fundamen...
8 substancestranspersonalmysticalpsychedelic
Spirituality enhancement
A profound intensification of spiritual feelings, mystical awareness, and a sense of sacred connection to something grea...
34 substancestranspersonalmysticalpsychedelic
Unity and interconnectedness
A profound sense that identity extends beyond the self to encompass other people, nature, or all of existence. Boundarie...
81 substancestranspersonalmysticalpsychedelic