Diphenhydramine Effects

Abnormal heartbeat (arrhythmia) is any deviation from the heart's normal rhythm — including beats that are too fast (tachycardia), too slow (bradycardia), or irregularly spaced — and represents one of the more medically significant cardiovascular effects of psychoactive substances.

A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete disinterest or even physical revulsion at the thought of eating. This effect can persist for many hours beyond the primary experience.

A diffuse, heavy physical discomfort involving tension, pressure, and malaise in the torso and limbs, commonly reported with tryptamines and phenethylamines.

Bronchodilation is the widening of the bronchial airways in the lungs, reducing resistance to airflow and producing a subjective sensation of easier, deeper, and more comfortable breathing.

A decreased desire and need to cough, medically known as antitussive action, which can also allow inhalation of larger amounts of smoke without triggering the cough reflex.

Decreased libido is a diminished interest in and desire for sexual activity, commonly caused by substances that suppress dopaminergic reward signaling, dampen emotional responsiveness, or induce sedation.

A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical discomfort, often caused by increased sweating, urination, or simply forgetting to drink water during substance use.

Difficulty urinating, also known as urinary retention, is the experience of being unable to easily pass urine despite a full bladder, commonly caused by stimulant, opioid, and anticholinergic substances that affect bladder muscle control.

A sensation of spinning, swaying, or lightheadedness that impairs balance and spatial orientation, often accompanied by nausea and difficulty standing or walking steadily.

A persistent, uncomfortable reduction in saliva production causing the mouth and throat to feel parched, sticky, and difficult to swallow through, commonly known as cottonmouth.

Increased urinary frequency beyond normal patterns, caused by diuretic effects or bladder irritation from substances like alcohol, caffeine, and ketamine.

Increased bodily temperature (hyperthermia) is an elevation of core body temperature above the normal 37C (98.6F) baseline, caused by substances that increase metabolic rate, impair thermoregulation, or promote sustained physical activity, and representing one of the most dangerous physical effects when severe.

A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a forceful, rapid pounding felt throughout the chest, neck, and temples. This effect is among the most commonly reported physiological responses to psychoactive substances and often accompanies stimulation, anxiety, or physical exertion during intoxication.

A persistent, diffuse urge to scratch the skin that arises without any external irritant, most commonly caused by opioid-induced histamine release, ranging from a mild tingling to an intense, widespread crawling sensation across the body.

A distinct decrease in the ability to control one's physical body with precision, balance, and coordination, ranging from minor clumsiness to complete inability to walk.

Muscle cramps are sudden, involuntary, and often painful contractions of muscles that occur as a side effect of certain psychoactive substances, particularly stimulating psychedelics and stimulants.

The experience of muscles throughout the body losing their rigidity and tension, becoming noticeably relaxed, loose, and comfortable.

Muscle twitching consists of small, involuntary, localized contractions or tremors within individual muscle groups — often visible as flickering movements under the skin — caused by heightened motor neuron excitability from stimulating substances.

An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting, often occurring during the onset phase of many substances.

Nausea suppression is the pharmacological reduction or elimination of nausea and the urge to vomit, achieved through substances that act on serotonin, dopamine, histamine, or cannabinoid receptors involved in the emetic reflex.

Perception of bodily heaviness is the subjective feeling that one's body has become dramatically heavier, resulting in movements feeling sluggish, effortful, and sometimes impossible, as though gravity has selectively increased its pull.

An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity, or a full-body orgasmic glow radiating outward from the core. This effect is often described as one of the most rewarding physical sensations available through psychoactive substances and is a primary driver of the recreational appeal of many substance classes.

Physical fatigue is a state of bodily exhaustion characterized by reduced energy, diminished capacity for physical activity, and an overwhelming desire to rest, commonly experienced during comedowns or as a direct effect of sedating substances.

A visible narrowing of the pupil diameter (miosis) that reduces the size of the dark center of the eye to a small pinpoint. This effect is one of the most reliable physical indicators of opioid intoxication and is often the first sign noticed by medical professionals and observers when assessing someone under the influence of opioids or certain other substance classes.

A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to dramatic saucer-like expansion where the dark pupil dominates the iris. This effect is one of the most recognizable signs of psychedelic and stimulant intoxication and directly contributes to light sensitivity, enhanced color perception, and the characteristic "wide-eyed" appearance.

A dangerous slowing and shallowing of breathing that can progress from barely noticeable reductions in respiratory rate to life-threatening cessation of breathing. This is the primary mechanism of death in opioid overdoses and represents one of the most critical safety concerns across all of psychopharmacology.

Restless legs is an uncomfortable neurological effect characterized by an irresistible compulsion to move the legs (and sometimes other limbs) to relieve unpleasant crawling, aching, or tingling sensations, particularly during periods of rest or inactivity.

A state of deep physical and mental calming that manifests as a progressive desire to remain still, lie down, and eventually drift toward sleep. Sedation ranges from a gentle drowsy relaxation to a heavy, irresistible pull into unconsciousness where maintaining wakefulness becomes a losing battle against the body's insistence on shutdown.

Uncontrolled brain electrical activity causing convulsions and loss of consciousness -- a life-threatening medical emergency requiring immediate help.

Serotonin syndrome is a potentially fatal medical emergency caused by excessive serotonergic activity in the central and peripheral nervous systems, typically resulting from combining multiple serotonin-elevating substances, and manifesting as a dangerous triad of neuromuscular hyperactivity, autonomic dysfunction, and altered mental status.

Visible reddening of the skin due to vasodilation, most prominent on the face and chest, commonly caused by alcohol and some psychedelics.

A state of heightened physical and mental energy characterized by increased wakefulness, elevated motivation, and a subjective sense of vigor that pervades both body and mind. Users often report feeling electrically alive, with a buzzing readiness to move, talk, and engage that can range from a pleasant caffeine-like lift to an overwhelming, jittery compulsion to act.

An involuntary clenching and rhythmic grinding of the jaw muscles, known clinically as bruxism, that produces a compulsive need to clench, chew, or gnash the teeth together. This effect can range from a subtle tightness in the jaw to forceful, repetitive grinding that can cause significant dental damage and jaw pain during and after the experience.

Impaired thermoregulation causing unpredictable fluctuations between feeling hot and cold, with risk of hyperthermia or hypothermia.

Temporary erectile dysfunction is the substance-induced inability to achieve or sustain a penile erection sufficient for sexual activity, caused by vasoconstriction, sympathetic nervous system overactivation, or altered neurotransmitter signaling, and resolving once the drug's effects wear off.

The sense of touch becomes dramatically heightened, making physical contact feel intensely pleasurable and detailed. Textures and skin contact produce amplified richness.

Tactile hallucinations are convincing physical sensations experienced without any corresponding external stimulus — phantom touches, crawling feelings, vibrations, pressure, temperature changes, or even pain and pleasure that originate entirely within the nervous system.

A progressive decrease in the ability to feel physical touch, ranging from mild numbness to complete bodily anaesthesia. The body may feel distant or absent.

Perceived increase or decrease in environmental brightness beyond actual illumination levels, common with stimulants and psychedelics (brightening) or sedatives (darkening).

The visual experience of seeing a single object as two separate, overlapping images, similar to crossing one's eyes, ranging from subtle ghosting to complete inability to perceive fine detail.

The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow, breathe, melt, or shift in position. Drifting is one of the most fundamental and commonly reported visual distortions under the influence of psychedelic substances, serving as the perceptual foundation upon which many other visual effects are built. It manifests as a fluid, organic sense of motion embedded in otherwise static visual fields.

A visual hallucination that manifests within the external environment as though it were physically real, ranging from subtle distortions of existing objects to fully autonomous, detailed scenes and entities that appear indistinguishable from reality.

The experience of perceiving complex, ever-shifting geometric patterns superimposed over the visual field or visible behind closed eyelids. Geometry is widely considered the hallmark visual effect of psychedelic substances, ranging from simple lattice patterns and honeycombs at low doses to infinitely complex, self-transforming fractal structures at high doses that can feel profoundly meaningful and awe-inspiring.

Vivid, detailed visual experiences perceived within an imagined mental landscape that can only be seen with closed eyes, ranging from fleeting imagery and abstract scenes to fully immersive, dream-like environments with autonomous narratives and entities.

A hallucinatory effect in which stationary objects in the environment appear to spontaneously move, animate, or behave as though they possess autonomous will — doors opening by themselves, cups sliding across tables, or furniture assembling and disassembling.

A visual effect in which objects in the environment appear to warp, stretch, melt, or animate autonomously, often returning to their original form when the observer looks away and then back.

A hallucinatory phenomenon in which the observer's visual perspective shifts from the normal first-person viewpoint to alternative vantage points — including third-person (seeing oneself from outside), bird's-eye, or omniscient perspectives — during both internal and external hallucinations.

The perceived environment in which hallucinatory experiences take place, ranging from recognizable locations drawn from memory to entirely novel alien landscapes, ancient civilizations, cosmic vistas, and impossible architectural spaces.

The perception of dark, humanoid silhouettes lurking in peripheral vision or standing in direct line of sight, appearing to move and behave as autonomous, sentient beings. These entities feel disturbingly real and are a hallmark of deliriant intoxication and sleep deprivation.

Objects and scenery undergo perceived visual metamorphosis, smoothly shapeshifting into other recognizable forms over seconds. Patterns morph into faces, animals, and imagery.

A deeply distressing hallucinatory state involving sustained exposure to nightmarish, terrifying, and personally threatening scenarios — often drawn from the individual's deepest fears — that can occur during high-dose experiences colored by negative emotion.

Vision becomes blurred, indistinct, and out of focus, as though looking through a smudged lens. Fine details degrade and edges lose their definition and sharpness.

A translucent fog or haze overlays the visual field, softening the environment and reducing clarity. May appear colorless or tinted, giving surroundings a dreamlike atmosphere.

A complete or partial inability to form new memories or recall existing ones during and after substance use, ranging from minor gaps in recollection to total blackouts encompassing hours of experience.

Analysis suppression is a cognitive impairment in which the capacity for logical reasoning, critical evaluation, and systematic problem-solving is significantly diminished — leaving the person unable to effectively break down, examine, or draw conclusions about even relatively simple ideas or situations.

Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to overwhelming panic attacks with a sense of impending doom, often amplified by the substance's intensification of one's existing mental state.

Mental exhaustion and difficulty sustaining thought after intense cognitive experiences, common during substance comedowns.

An impairment of abstract thinking marked by a persistent inability to grasp or comprehend concepts and situations that would normally be perfectly understandable during sobriety.

Creativity suppression is a decrease in both the motivation and the cognitive capacity for creative output — manifesting as a frustrating inability to generate novel ideas, make original connections, produce artistic work, or think outside established patterns and frameworks.

Delirium is a serious and potentially dangerous state of acute mental confusion involving disorientation, incoherent thought, impaired attention, and frequently vivid hallucinations that the person cannot distinguish from reality. It represents one of the most medically concerning cognitive effects of substance use.

A delusion is a fixed, false belief that is held with unshakeable certainty and is impervious to contradicting evidence or rational argument — often involving grandiose, persecutory, or bizarre themes that are clearly at odds with observable reality.

A persistent state of low mood, emotional numbness, hopelessness, and diminished interest or pleasure in activities, often occurring during comedowns, withdrawal, or as a prolonged after-effect of substance use.

A perceptual disturbance in which the external world feels profoundly unreal, dreamlike, or artificially constructed, as though experienced through a veil, screen, or foggy barrier separating the observer from reality.

A marked reduction in social inhibitions, self-consciousness, and behavioral restraint that manifests as increased openness, talkativeness, and willingness to engage in activities one would normally avoid. Users often describe feeling as though an invisible social barrier has been lifted, allowing thoughts and impulses to flow directly into action without the usual filtering process.

Enhanced dream vividness, complexity, and recall, often occurring as REM rebound after discontinuing REM-suppressing substances.

A blunting or flattening of emotional experience in which feelings become muted, distant, or seemingly absent. The individual may recognize intellectually that they should be feeling something in response to a situation — joy at good news, sadness at a loss, anxiety about a threat — yet the emotional charge simply is not there, as though an invisible pane of glass separates them from their own feelings.

Feelings of impending doom is the sudden onset of an overwhelming, visceral certainty that something terrible is about to happen — often one's own death, a medical crisis, or the end of the world — despite the absence of any rational basis for this belief.

Focus suppression is a diminished capacity to direct and sustain attention on a chosen target — a task, a thought, a conversation — while successfully ignoring competing stimuli, resulting in persistent distractibility and difficulty completing even simple cognitive activities.

Glossolalia is the experience of spontaneously speaking or thinking in patterns of syllables that sound and feel like a real language — complete with apparent grammar, intonation, and rhythm — but that carry no actual semantic meaning.

Irritability is a sustained state of emotional reactivity in which the threshold for annoyance, frustration, and anger is significantly lowered — causing minor inconveniences, social interactions, or environmental stimuli that would normally be tolerated without difficulty to provoke disproportionate agitation or hostility.

A diminished ability to formulate, comprehend, or articulate language, ranging from difficulty finding the right words to a near-complete inability to construct coherent sentences or understand speech, despite remaining otherwise conscious.

Abnormally elevated mood, energy, and activity with impulsive behavior and grandiosity, associated with stimulant use and certain drug interactions.

A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ranging from mild forgetfulness to a profound inability to recall personal identity, biographical information, or the context of the current experience.

Motivation suppression is a state of diminished drive and willingness to engage in goal-directed behavior — from everyday tasks like cleaning and working to activities that would normally be experienced as rewarding or enjoyable — sometimes described as a profound and enveloping 'why bother?' feeling.

Irrational suspicion and belief that others are watching, plotting against, or intending harm toward oneself, ranging from mild unease to overwhelming terror.

Psychosis is a serious psychiatric state involving a fundamental break from consensus reality — characterized by firmly held false beliefs (delusions), perception of things that are not there (hallucinations), disorganized thought and speech, and a loss of the ability to distinguish internal mental events from external reality.

Sensed presence is the vivid and often unshakeable feeling that an unseen conscious being — whether benevolent, malevolent, neutral, or inscrutable — is present nearby or within one's own mind, despite the complete absence of any visual, auditory, or tactile confirmation.

A progressive onset of drowsiness, heaviness, and the desire to sleep that pulls the individual toward rest with increasing insistence. The eyelids feel weighted, the body sinks into whatever surface supports it, cognitive activity winds down into a pleasant fog, and the transition from waking consciousness toward sleep begins to feel not only appealing but inevitable.

The experience of thoughts occurring at a markedly reduced pace, as if the mind has been placed into slow motion. Internal dialogue becomes sparse and sluggish, with each idea taking longer to form and process, producing a sense of mental heaviness or cognitive inertia.

Thought disorganization is a cognitive impairment in which the normal capacity for structured, sequential, and logical thinking becomes significantly disrupted, causing thoughts to become scattered, tangential, and difficult to follow to completion.

Subjective perception of time becomes dramatically altered — minutes may feel like hours, or hours pass in moments. Can manifest as either dilation or compression.

An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation in that it does not elevate energy above a naturally rested baseline.

Auditory enhancement is a heightened sensitivity and appreciation of sound in which music, voices, and ambient noise become richer, more detailed, and more emotionally resonant. Subtle sonic details that would normally go unnoticed — the texture of a guitar string, the breath between a singer's words, the layered harmonics of a chord — become vivid and captivating.

Auditory hallucination is the perception of sounds that have no external source — hearing music, voices, environmental noises, or abstract sonic phenomena that exist entirely within the mind. These range from faint, ambiguous whispers at the edge of perception to fully formed, complex musical compositions or conversational speech that can feel completely real and externally sourced.

A dampening of auditory perception in which sounds become muffled, distant, and reduced in both volume and clarity, as though hearing through thick walls or underwater. This creates a cocoon-like sense of auditory isolation.

Gustatory hallucinations are phantom taste experiences in which distinct flavors manifest in the mouth without any corresponding food, drink, or chemical stimulus. They range from common metallic or chemical tastes to complex, sometimes entirely alien flavor profiles.

Memory replays are vivid, multisensory re-experiences of past events that go far beyond normal recall — the person doesn't just remember an event but relives it as an immersive hallucination, complete with sights, sounds, emotions, and physical sensations from the original experience.

Olfactory hallucinations (phantosmia) involve the perception of convincing phantom smells — pleasant, foul, or utterly strange — that have no corresponding source in the person's actual environment.

Scenarios and plots are the narrative structures that emerge within hallucinatory states — coherent or surreal storylines involving autonomous characters, unfolding events, and immersive settings that can feel as real and consequential as waking life.