2C-I (2,5-dimethoxy-4-iodophenethylamine) is a psychedelic phenethylamine of the 2C family first synthesized by Alexander Shulgin and described in PiHKAL (1991). The 4-iodo substituent gives it slightly higher potency than 2C-B and a more stimulant-forward character, producing an energetic, sociable psychedelic experience at doses of 14–22 mg with a duration of 6–8 hours. 2C-I became one of the most widely distributed research chemicals in the early 2000s, particularly in Europe, where it was sold legally until scheduling actions swept through most jurisdictions between 2004 and 2012.
The 2C-I experience is frequently described as bridging the recreational warmth of 2C-B and the analytical depth of 2C-E — more stimulating and socially engaging than 2C-B, less cerebrally demanding than 2C-E, with pronounced visual effects, tactile enhancement, and a generally positive mood elevation at moderate doses. The stimulant component can produce uncomfortable restlessness, jaw clenching, and wakefulness at higher doses, and the extended duration (8 hours is common) can contribute to physical fatigue.
Like all 2C compounds, 2C-I carries psychological risks proportional to dose and individual factors. Its period of widespread commercial availability generated substantial community experience, making it one of the better-documented 2C compounds despite never having formal clinical research attention. A notable safety concern specific to 2C-I is that blotter paper sold as "2C-I" was responsible for a wave of NBOMe compound poisonings in the 2010s when vendors substituted the cheaper and far more toxic 25I-NBOMe — a compound that visually and physically resembles LSD blotter but produces dramatic and potentially lethal physiological toxicity.
Safety at a Glance
High Risk- Test Your Substance
- Dose and Duration
- Toxicity: General Safety Profile 2C-I has been used by large numbers of people without documented fatalities attributable to it...
- Overdose risk: Fatal overdose from 2C-I alone, at doses within the typical recreational range, is extremely unli...
If someone is in crisis, call 911 or Poison Control: 1-800-222-1222
Dosage
oral
Duration
oral
Total: 6 hrs – 10 hrsHow It Feels
The onset builds over thirty to forty-five minutes with a clean, bright energy. A stimulant warmth rises through the body, and the first visual changes appear as a sharpening of color and detail -- the world seems to come into higher definition, as though a camera has shifted from auto to manual focus. There is often a distinct sense of anticipation and excitement. Nausea is uncommon and usually mild when present. The body feels energized and light, and there is a social brightening -- a desire to talk, laugh, and engage -- that begins even before the visual effects have fully established themselves.
By the one-hour mark, the visual component has opened into a vivid, accessible psychedelic landscape. Colors are brilliantly saturated and seem to radiate warmth. Geometric patterns appear with moderate density, tending toward clean, symmetrical forms that tile across surfaces with pleasing regularity. The patterns have a crystalline, jewel-like quality -- precise and intricate but never overwhelming. Surfaces shimmer and breathe gently. Afterimages are mild but persistent, creating a subtle trailing effect behind moving objects. The overall visual character is bright, detailed, and aesthetically rewarding -- more decorative than profound, more beautiful than strange.
The headspace is the quality that truly distinguishes 2C-I from its relatives. It is remarkably clear, lucid, and manageable. The mind remains fully functional -- capable of conversation, navigation, and even relatively complex thought -- while simultaneously experiencing strong visual psychedelia. There is a significant euphoric component, a buoyant mood lift that makes social situations feel effortless and joyful. Music is vividly enhanced, and the combination of visual beauty, mental clarity, and emotional warmth makes the experience feel celebratory. The body load is light: a moderate stimulant energy that encourages movement and activity, mild pupil dilation, and occasional jaw tension. The substance seems designed for engagement with the external world rather than inward retreat.
The peak lasts two to four hours, and total effects span six to eight hours. The comedown is smooth and gradual, with visual effects fading gently while the mood lift persists. There is typically no crash or hangover -- the aftermath is clean and often includes a pleasant afterglow of social warmth and visual appreciation that can last into the following day. 2C-I delivers its gifts with an easy generosity, asking little in return.
Subjective Effects
The effects listed below are based on the Subjective Effect Index (SEI), an open research literature based on anecdotal reports and personal analyses. They should be viewed with a healthy degree of skepticism. These effects will not necessarily occur in a predictable or reliable manner, although higher doses are more liable to induce the full spectrum of effects.
Physical Effects
Physical(14)
- Appetite suppression— A distinct decrease in hunger and desire to eat, ranging from reduced interest in food to complete d...
- Bodily control enhancement— Bodily control enhancement is the subjective feeling of improved physical precision, coordination, a...
- Body load— A diffuse, heavy physical discomfort involving tension, pressure, and malaise in the torso and limbs...
- Dehydration— A state of insufficient bodily hydration manifesting as persistent thirst, dry mouth, and physical d...
- Frequent urination— Increased urinary frequency beyond normal patterns, caused by diuretic effects or bladder irritation...
- Increased heart rate— A noticeable acceleration of heartbeat that can range from a subtle awareness of one's pulse to a fo...
- Increased libido— A marked enhancement of sexual desire, arousal, and sensitivity to erotic stimuli that can range fro...
- Muscle cramp— Muscle cramps are sudden, involuntary, and often painful contractions of muscles that occur as a sid...
- Nausea— An uncomfortable sensation of queasiness and stomach discomfort that may or may not lead to vomiting...
- Physical euphoria— An intensely pleasurable bodily sensation that can manifest as waves of warmth, tingling electricity...
- Pupil dilation— A visible enlargement of the pupil diameter (mydriasis) that can range from subtle widening to drama...
- Stamina enhancement— Stamina enhancement is an increase in one's ability to sustain physical and mental exertion over ext...
- Stimulation— A state of heightened physical and mental energy characterized by increased wakefulness, elevated mo...
- Temperature regulation disruption— Impaired thermoregulation causing unpredictable fluctuations between feeling hot and cold, with risk...
Tactile(1)
- Tactile enhancement— The sense of touch becomes dramatically heightened, making physical contact feel intensely pleasurab...
Cognitive & Perceptual Effects
Visual(16)
- Colour enhancement— An intensification of the brightness, vividness, and saturation of colors in the external environmen...
- Colour shifting— The visual experience of colors on objects and surfaces cycling through continuous, fluid transforma...
- Drifting— The visual experience of perceiving stationary objects, textures, and surfaces as appearing to flow,...
- Environmental cubism— A visual distortion in which the environment and objects within it appear fragmented into geometric,...
- Environmental patterning— A visual effect in which existing textures and surfaces — carpets, clouds, foliage, walls — spontane...
- External hallucination— A visual hallucination that manifests within the external environment as though it were physically r...
- Geometry— The experience of perceiving complex, ever-shifting geometric patterns superimposed over the visual ...
- Internal hallucination— Vivid, detailed visual experiences perceived within an imagined mental landscape that can only be se...
- Pattern recognition enhancement— An increased ability and tendency to perceive meaningful patterns, faces, and images within ambiguou...
- Perspective hallucination— A hallucinatory phenomenon in which the observer's visual perspective shifts from the normal first-p...
- Scenery slicing— The visual field fractures into distinct, cleanly cut sections that slowly drift apart from their or...
- Settings, sceneries, and landscapes— The perceived environment in which hallucinatory experiences take place, ranging from recognizable l...
- Symmetrical texture repetition— Textures appear to mirror and tessellate across surfaces in intricate, self-similar symmetrical patt...
- Tracers— Moving objects leave visible trails of varying length and opacity behind them, similar to long-expos...
- Transformations— Objects and scenery undergo perceived visual metamorphosis, smoothly shapeshifting into other recogn...
- Visual acuity enhancement— Vision becomes sharper and more defined than normal, as though a slightly blurry lens has been broug...
Cognitive(9)
- Analysis enhancement— A perceived improvement in one's ability to logically deconstruct concepts, recognize patterns, and ...
- Anxiety— Intense feelings of apprehension, worry, and dread that can range from a subtle background unease to...
- Emotion suppression— A blunting or flattening of emotional experience in which feelings become muted, distant, or seeming...
- Immersion enhancement— A heightened capacity to become fully absorbed and engrossed in external media such as music, films,...
- Memory suppression— A dose-dependent inhibition of one's ability to access and utilize short-term and long-term memory, ...
- Novelty enhancement— A feeling of increased fascination, awe, and childlike wonder attributed to everyday concepts, objec...
- Paranoia— Irrational suspicion and belief that others are watching, plotting against, or intending harm toward...
- Time distortion— Subjective perception of time becomes dramatically altered — minutes may feel like hours, or hours p...
- Wakefulness— An increased ability to stay awake and alert without the desire to sleep. Distinct from stimulation ...
Multi-sensory(2)
- Scenarios and plots— Scenarios and plots are the narrative structures that emerge within hallucinatory states — coherent ...
- Synaesthesia— Stimulation of one sense triggers involuntary experiences in another — seeing sounds as colors, tast...
Transpersonal(2)
- Ego death— A profound dissolution of the sense of self in which personal identity, memories, and the boundary b...
- Unity and interconnectedness— A profound sense that identity extends beyond the self to encompass other people, nature, or all of ...
Pharmacology
Mechanism of Action
2C-I acts as a partial agonist at serotonin 5-HT2A receptors, sharing the primary mechanism of all classical phenethylamine psychedelics. The 4-iodo substituent produces robust 5-HT2A binding affinity — slightly higher than 2C-B in most comparative binding studies — consistent with iodine's large size and high lipophilicity enhancing receptor interactions.
Stimulant Character
Relative to 2C-B, 2C-I has a more pronounced stimulant character. This is attributed to modestly greater activity at monoamine transporters compared to purely halogen-substituted analogs with smaller halogens. The stimulant component produces the elevated heart rate, alertness, and social energy that users describe, alongside the less comfortable manifestations of stimulant activity at higher doses.
Pharmacokinetics
No formal human pharmacokinetic studies exist. The 6–8 hour duration is somewhat longer than 2C-B (4–6 hours), consistent with iodine's greater metabolic stability compared to bromine at the 4-position. First-pass hepatic metabolism is expected to be significant for oral dosing.
Tolerance
Functional tolerance develops within 24–48 hours of repeated use. Cross-tolerance with other serotonergic psychedelics (psilocybin, LSD, mescaline, 2C-B) is expected and is largely complete at standard psychedelic doses.
Detection Methods
Urine Detection
2C-I is not specifically targeted by standard immunoassay-based urine drug panels. However, because 2C-x phenethylamines share structural features with amphetamines, they may trigger false positives on amphetamine immunoassays in some cases. The likelihood of cross-reactivity depends on the specific immunoassay manufacturer and the antibody selectivity used. Urine detection windows for 2C-I are estimated at 24 to 72 hours following ingestion when analyzed by LC-MS/MS methods, though limited pharmacokinetic data exists for many 2C-x compounds.
Blood and Serum Detection
Blood detection windows for 2C-I are approximately 6 to 24 hours after oral administration. Peak plasma concentrations typically occur 1 to 3 hours post-ingestion. The relatively short half-lives of most 2C-x phenethylamines mean that blood testing must be performed promptly to capture detectable concentrations. LC-MS/MS is the only reliable method for quantitative blood analysis.
Standard Drug Panel Inclusion
2C-I is NOT specifically included on standard 5-panel, 10-panel, or 12-panel drug screens. The primary concern for individuals undergoing routine screening is the potential for amphetamine cross-reactivity on immunoassay-based panels. If a presumptive positive for amphetamines occurs, confirmatory testing by GC-MS or LC-MS/MS would not confirm amphetamine and the result would be reported as negative unless the laboratory specifically tests for 2C-x compounds. Most routine laboratories do not include 2C-x phenethylamines in their confirmatory panels.
Confirmatory Methods
Definitive identification of 2C-I requires LC-MS/MS or GC-MS with appropriate reference standards. Some forensic toxicology laboratories include 2C-x phenethylamines in their extended novel psychoactive substance panels. Immunoassay cross-reactivity alone is insufficient for confirmation and would be resolved by standard confirmatory procedures. Quantitative analysis typically requires specific method development as these compounds are not part of routine clinical chemistry workflows.
Reagent Testing (Harm Reduction)
For harm reduction identification, the Marquis reagent is a primary screening tool for 2C-I. The Marquis reagent produces an orange to brown reaction with 2C-I, distinguishing it from most other 2C-x compounds. The Mecke reagent may provide additional color reactions that help differentiate between specific 2C-x variants. The Ehrlich reagent shows no reaction with 2C-x phenethylamines, which can help distinguish them from tryptamines and lysergamides. The Mandelin reagent may produce green to brown reactions depending on the specific compound. Using multiple reagents in combination provides the most reliable field identification, though reagent testing cannot determine purity or dosage.
Interactions
| Substance | Status | Note |
|---|---|---|
| 3-FMA | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| 4-MMC | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| 8-Chlorotheophylline | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| Adrafinil | Caution | Increases anxiety, cardiovascular stress, and psychological intensity |
| Anandamide | Caution | Cannabis can unpredictably intensify psychedelic effects and increase anxiety |
| Cannabis | Uncertain | — |
| 1,3-Butanediol | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 25E-NBOH | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 2C-T | Low Risk & Synergy | Cross-tolerance exists; effects compound |
| 2C-T-2 | Low Risk & Synergy | Cross-tolerance exists; effects compound |
History
Shulgin and PiHKAL
2C-I was first synthesized by Alexander Shulgin as part of his systematic 4-substituted 2,5-dimethoxyphenethylamine series. It is documented in PiHKAL (1991) alongside the other named 2C compounds. Shulgin's bioassay noted the compound's potency and stimulant character, establishing its profile within the series.
Research Chemical Era
2C-I became one of the most commercially prominent research chemicals in the early 2000s, particularly in Europe where it was briefly sold legally as a "designer drug." Its relatively accessible price, online availability, and well-documented experience profile made it a gateway substance for many users entering the research chemical space. Erowid's Experience Vaults accumulated hundreds of 2C-I reports during this period.
NBOMe Contamination Crisis
The substitution of 25I-NBOMe for 2C-I (and 2C-B) on blotter paper became a major harm reduction crisis in the early 2010s. Multiple fatalities were attributed to the substitution. This prompted warnings from harm reduction organizations worldwide and was a significant driver of broader drug checking advocacy.
Scheduling
2C-I was explicitly scheduled as Schedule I in the United States under the Synthetic Drug Abuse Prevention Act of 2012. It is controlled in most European and other jurisdictions.
Harm Reduction
Test Your Substance
Given the documented history of 25I-NBOMe being sold as 2C-I, reagent testing is non-negotiable. Use an Ehrlich reagent — 2C-I will not produce a color change (it is a phenethylamine, not an indole), but 25I-NBOMe will also not change Ehrlich. Use aMecke orMarquis reagent for phenethylamine confirmation. If the substance is on blotter paper, be highly suspicious — 2C-I is not normally distributed on blotter.
Dose and Duration
- Threshold: 8–12 mg | Common: 14–22 mg | Strong: 22–30 mg
- Duration: 6–8 hours active; expect difficulty sleeping for 10–12 hours after dosing
- Start low for first experience; the stimulant component can be more uncomfortable at higher doses than the psychedelic intensity
Plan for the Duration
8 hours of active effects requires setting aside essentially an entire day. The stimulant component means sleep will be difficult until at least 10–12 hours post-dosing. Do not use in situations where next-day obligations are critical.
Dangerous Combinations
Toxicity & Safety
General Safety Profile
2C-I has been used by large numbers of people without documented fatalities attributable to its direct pharmacological action. However, the NBOMe adulteration risk (see below) represents a serious historical safety concern.
NBOMe Adulteration
The most significant safety risk associated with "2C-I" as encountered outside a trusted supply chain is adulteration with 25I-NBOMe — a compound that is 100-fold more potent, produces dramatically different physiological effects, and has caused multiple fatalities. 25I-NBOMe is active on blotter paper at microgram quantities; 2C-I requires milligram quantities and is not typically dosed on blotter. Any blotter paper claiming to be 2C-I should be considered a serious red flag.
Cardiovascular Effects
Sympathomimetic effects are more pronounced than with 2C-B or 2C-C due to the greater stimulant component. Tachycardia and elevated blood pressure are common. Individuals with cardiovascular conditions should not use 2C-I.
Psychological Risks
At higher doses, the combined stimulant and psychedelic load can produce anxiety, paranoia, and psychological overwhelm. The extended duration means a difficult experience will persist.
Drug Interactions
Addiction Potential
not habit-forming
Overdose Information
Fatal overdose from 2C-I alone, at doses within the typical recreational range, is extremely unlikely based on the available evidence for classical psychedelics. The therapeutic index for most psychedelics is very wide.
However, psychological emergencies can occur and require appropriate response:
- Severe anxiety, panic, or psychotic episodes
- Dangerous behavior due to impaired reality testing
- Self-harm in the context of a distressing experience
Emergency management: If someone is experiencing a severe adverse reaction, move them to a calm, quiet environment. Speak reassuringly. Do not restrain unless there is immediate danger. Benzodiazepines (if available and the person is conscious and able to swallow) can reduce acute anxiety. If psychotic symptoms, self-harm risk, or medical distress is present, seek emergency medical attention.
Medical attention: Seek help immediately for seizures, extremely elevated body temperature, signs of serotonin syndrome (agitation, tremor, diarrhea, rapid heart rate), or if the substance consumed is uncertain.
Tolerance
| Full | almost immediately after ingestion |
| Half | 3-5 days |
| Zero | 7-10 days |
Cross-tolerances
Legal Status
In November 2003, the European Council decided that 2C-I shall be subjected by the Member States to control measures and criminal penalties within three months.
Austria: 2C-I is illegal to possess, produce and sell under the SMG. (Suchtmittelgesetz Österreich)
Brazil: Possession, production and sale is illegal as it is listed on Portaria SVS/MS nº 344.
Canada: 2C-I is a schedule III controlled substance in Canada.
Denmark: 2C-I is a controlled substance in Denmark.
Germany: 2C-I is controlled under Anlage I BtMG (Narcotics Act, Schedule I) as of October 10, 1999. It is illegal to manufacture, possess, import, export, buy, sell, procure or dispense it without a license.
Greece: 2C-I is a controlled substance in Greece.
Ireland: 2C-I is a controlled substance in Ireland.
Italy: 2C-I is a controlled substance in Italy.
Latvia: 2C-I is a Schedule I controlled substance Latvia.
The Netherlands: 2C-I is a controlled substance in the Netherlands.
Poland: 2C-I is a controlled substance in Poland.
Sweden: Sveriges riksdag added 2C-I to Schedule I ("substances, plant materials and fungi which normally do not have medical use") as a narcotic in Sweden as of March 16, 2004.
Switzerland: 2C-I is a controlled substance specifically named under Verzeichnis D.
Turkey: 2C-I is classed as a drug and is illegal to possess, produce, supply, or import.
United Kingdom: 2C-I is a Class A drug in the United Kingdom as a result of the phenethylamine catch-all clause.
United States: As of July 9, 2012, 2C-I is a Schedule I substance in the U.S. under the Synthetic Drug Abuse Prevention Act of 2012, making possession, distribution and manufacture illegal.
Experience Reports (1)
Tips (3)
Use a milligram scale to weigh 2C-I if it comes as a powder. Eyeballing doses of potent psychedelics is irresponsible. A quality 0.001g scale costs under $30 and could prevent a seriously overwhelming experience.
Psychedelic tolerance builds rapidly. Wait at least 1-2 weeks between uses of 2C-I for full tolerance reset. Taking the same dose the next day would require roughly double the amount for comparable effects.
Integration is just as important as the experience itself. After using 2C-I, take time to journal, reflect, or discuss the experience. Insights from psychedelic states can be powerful but need conscious effort to apply to daily life.
See Also
References (4)
- Psilocybin produces substantial and sustained decreases in depression and anxiety — Griffiths et al. Journal of Psychopharmacology (2016)paper
- Neural correlates of the LSD experience revealed by multimodal neuroimaging — Carhart-Harris et al. PNAS (2016)paper
- 2C-I - TripSit Factsheet
TripSit factsheet for 2C-I
tripsit - 2C-I - Wikipedia
Wikipedia article on 2C-I
wikipedia