2C-I chemical structure and 2C-I powder
2C-I chemical structure and 2C-I in powdered form

2C-I Unveiled—From Research Chemical to Party Psychedelic

We cover the risks and research behind this mind-bending phenethylamine

DoubleBlind Mag

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Published on
Updated December 23, 2023

DoubleBlind // Psychedelic Guides

2C-B. DiPT. 4-AcO-DMT. When it comes to the names of novel psychedelic compounds, it sometimes feels like all that’s missing is an “H-I-J-K-L-M-N-O-P.” These new compounds are “research chemicals” or “designer drugs.” Their letter and number names represent the arrangement of atoms in each molecular compound. Yet amid this alphabet soup lies a wildly diverse range of possible experiences for the explorer. But, it’s vital to approach these compounds with caution, knowledge, and respect. 

Today, we’re focusing on 2C-I, also known as the “smile drug.” The drug is one of the most widespread psychedelics within the “2C” family, which also includes 2C-B and lesser-known compounds like 2C-T-7. The family belongs to a larger classification of chemicals called phenethylamines. Most drugs in the 2C family were first synthesized by pioneer chemist Alexander “Sasha” Shulgin in the 1970s and 1980s. Shulgin infamously tested many of these compounds himself and shared them with close friends. He documented their experiences in his 1991 book PiHKAL: A Chemical Love Story (“PiHKAL” stands for “Phenethylamines I Have Known and Loved”). 

Though 2C-I is a Schedule I-banned substance in the US and widely illegal throughout Europe, it continues to be popularly discussed on sites like Reddit and Erowid by psychonauts interested in experimenting with research chemicals.

What is 2C-I, Anyway? An Introduction to the “Smiles Drug”

Scientifically speaking, 2C-I is a phenethylamine. It belongs to a diverse class of organic compounds that stimulate the central nervous system of humans. Phenethylamines are found naturally in plants, bacteria, fungi, and animals, but they can also be made in a lab. Many well-known stimulants are phenethylamines, including:

  • amphetamine
  • methamphetamine
  • MDMA
  • antidepressants like Wellbutrin 

There are dozens of known 2C drugs, from 2C-B to 2C-G-6. While most are rarely synthesized or sold, others are commonly found in recreational contexts. 

Within the phenethylamine class is the “2C” family of drugs (named by Shulgin for the two carbon atoms between the benzene ring and the amino group), most of which produce psychedelic effects that vary greatly in their nature and strength. 2C drugs have been studied for their emotional and physiological effects—along with their potential risks of neurotoxicity and death. The smiles drug made headlines in 2012 after two teens died after consuming a possibly tainted batch; experts at the time cited warnings about the cardiovascular risks of the psychedelic.

2C-I 3D chemical structure | Wikimedia Commons

Clancy Beckers works in crisis intervention, peer education, and festival crowd care with the Australian harm reduction group DanceWize NSW. As they explained to DoubleBlind, 2C-I is a “versatile psychedelic substance that offers a balanced array of visual and emotional effects, [but] like any drug, it has its own set of risks and considerations, so it’s essential to approach its use cautiously and responsibly.”

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“…like any drug, it has its own set of risks and considerations, so it’s essential to approach its use cautiously and responsibly.”

A Chemical History

Much like DiPT and other psychedelics tested by Alexander Shulgin, 2C-I emerged during the first psychedelic boom, when scientists excitedly sought out new compounds that might have the unique, possibly therapeutic effects observed in LSD research. Paul Daley is the co-founder and chief science officer of the Alexander Shulgin Research Institute, which exists to further Shulgin’s legacy in chemical discoveries. In 2010, he told OpenDemocracy that the study of synthetic phenethylamines like 2C-I “began in 1949 with the creation of the first synthetic analog of mescaline.”  

Mescaline is a phenethylamine that occurs naturally in peyote and San Pedro cacti, whose ritual use by Indigenous peoples stretches back thousands of years. The pursuit of synthetic compounds that could offer similarly profound experiences led to the creation of hundreds of new drugs. While the scientific establishment tested a variety of compounds known as tryptamines, including LSD and DMT, Shulgin was the first to synthesize most of the phenethylamines documented in his writings. 

Daley tells DoubleBlind that mescaline was responsible for one of Shulgin’s first psychedelic experiences. Seeking to invent something similar but more potent, Shulgin tested different ways of arranging the phenethylamine chemical structure. Shulgin first became interested in TMA (or “mescalamphetamine”), which he found less “friendly” than mescaline, says Daley. Next came TMA2, which was similar but more potent, and then DOM, which became popular in 1967 under the name STP (“serenity, tranquility, peace”) but soon fell out of use due to its side effects and duration: A DOM trip lasts up to 14 hours. Small differences in chemical structure can produce large differences in effect.

Phikal: A Chemical Love Story book cover
Most drugs in the 2C family were first synthesized by pioneer chemist Alexander “Sasha” Shulgin in the 1970s and 1980s, who tested many of these compounds himself, shared them with close friends, and documented their experiences in his 1991 book PiHKAL: A Chemical Love Story

Finally, in 1974, Shulgin synthesized 2C-B. He came up with 2C-I soon after by placing an iodine atom (I) in the core position of the 2C “scaffold,” where 2C-B had bromine (B). The 2Cs were a breakthrough for Shulgin because while their primary action still affected the serotonin system, they were shorter-acting than other phenethylamines. Shulgin considered the 2C compounds some of his most important contributions to the field of psychedelic research. 

What is Smiles Like? A Brief Exploration of 2C-I Effects

Like other 2C compounds, 2C-I changes how one perceives themselves and their environment. Users typically experience heightened intensity of color, contrast, and detail, patterning and animation of objects, and complex visual hallucinations with eyes closed. There are also psychological effects, which DanceWize’s Beckers describes as “providing a balanced emotional experience [that is] neither too intense nor too mellow,” though it “doesn’t typically offer profound spiritual insights or revelations.” As with any psychedelic, 2C-I experiences vary greatly depending on dosage and other factors.

For Daley, 2C-I’s generation of form and imagery is similar to mescaline: one might experience something like “an unending distance of jewel-encrusted castles,” or “large fields of pastel colors with fractal framing around the edges,” he says. “It can be quite delightful.” Beckers says that the 2C-I visuals “are generally less intricate than those from substances like LSD, [but] are generally more manageable and can be very enjoyable.” 

2C-I powder
2C-I in powder form | via Wikimedia Commons

In Shulgin’s book Phenethylamines I Have Known And Loved, early 2C-I users commented on its similarity to 2C-B, which Shulgin called “one of the most graceful, erotic, sensual, introspective compounds I have ever invented.” Both drugs impart similar visuals and can allow for feelings of openness, honesty, and increased energy without being as cerebral as LSD. However, one early user remarked that 2C-I offered “slightly less than full immersion in the sensual.” An anonymous DanceWize NSW staff member said that taking 2C-I “wasn’t quite that balanced combination akin to candy-flipping [taking psychedelics with MDMA]” that they experienced on 2C-B. 

The same anonymous staffer felt their “body was a bit heavy” on 2C-I, though Beckers says 2C-I has a “gentler” body load than some other 2C compounds; “while some nausea and muscle cramping have been reported, these symptoms are usually less severe and occur less frequently compared to other psychedelics.” Most 2C-I users report a smooth, easy comedown, without a next-day hangover or fatigue. 

On the flip side, one anonymous DanceWize NSW volunteer called the 2C-I experience “freaky,” and said that after consuming it in crystal form, “the walls were melting and I was incapable of speech.” They said they never plan to take the drug again: “The paranoia was too much. Designer drugs are too much of a mixed bag.”

Harm Reduction Tips

“Though considered relatively safe at moderate dosages, 2C-I isn’t devoid of risks,” says Beckers. 2C-I can cause racing heartbeats, hypertension, and even respiratory depression. There is also a risk of serotonin syndrome, particularly if mixed with serotonergic agents like MAOIs and SSRIs. Combining 2C-I with other psychedelics—including cannabis and ketamine—can make the trip unpredictable, possibly more intense, and may impact cardiovascular health. Caffeine and other stimulants also elevate the cardiovascular risk, while opioids can increase the risk of respiratory depression. There is also a legal risk to possessing any banned substance.

Safety Note

Combining 2C-I with other psychedelics—including cannabis and ketamine—can make the trip unpredictable, possibly more intense, and may impact cardiovascular health. Caffeine and other stimulants also elevate the cardiovascular risk, while opioids can increase the risk of respiratory depression. There is also a legal risk to possessing any banned substance.

Because of these risks, DanceWize NSW and other harm reduction advocates suggest starting with a low dose to gauge your individual response. A threshold dose of 2C-I (when one would notice some effect) is typically 2 milligrams. A “mid-range” dose expected to produce a “balanced” psychedelic experience is 10 to 20 milligrams, while a “strong” dose of 20 to 30 milligrams may be overwhelming for some, and more than 30 milligrams greatly increases the risks of physical discomfort and psychological distress.

Yet those dosing guidelines are only accurate if you know what you’ve got. Substance purity varies greatly, and “poorly synthesized 2C-I can include contaminants that you don’t want in your system,” says Beckers. It is thus important to weigh your dose with a reliable scale and, if possible, use a reagent test (such as Marquis or Mecke) to indicate the presence of 2C drugs. However, these will not confirm the substance’s purity, potency, or exact identity. Only quantitative testing, like testing conducted by labs offering mail-in services, can give you a full profile of the substance you possess.

Beckers also suggests considering your “set” (psychological and emotional landscape) since 2C-I can trigger underlying anxieties, distress, or pre-existing conditions, as well as “Setting”: “Ensure you are in a controlled, comfortable environment, preferably with a sober trip-sitter to assist if things go south,” says Beckers. They implore potential user to exercise “extreme caution” if they have cardiovascular or psychiatric disorders. 

DanceWize NSW has published a guide with their accumulated safety advice for using drugs in the 2C-I family. For their general harm reduction principles, scroll down to the “Keepin’ it Safe(r)” section of our article on DiPT

DanceWize promotes the principle of set and setting, formulating it as follows:

Know your mind

Know your body

Know your environment

Know your limits

Curious about what these mean? Journalist Delilah Friedler has the details in our complete article.

How Long Does 2C-I Last?

According to Beckers of DanceWize NSW, the effects of 2C-I set in rather quickly, sometimes within minutes, peak two to three hours in, and wear off after five to six hours. The DEA says 2C-I’s effects begin after approximately 40 minutes, peak at the two-hour mark, and can last for up to eight hours. Online source Psychonaut Wiki claims the total duration can be up to ten hours, though based on anecdotal reports, that duration doesn’t seem common. However, the timeline can vary greatly based on dosing, as well as mindset, setting, and what other drugs one has taken. 

2C-I is generally known to have a shorter duration than psychedelics like LSD, making it more manageable for some users. Shulgin cited the relatively short duration of most drugs in the 2C family as a valuable characteristic; if a drug were to be used for therapeutic contexts, patients would likely find it more convenient to not be tripping all night. However, this is not the case for all 2C drugs. 2C-T-7, for instance, is said to produce effects for 8 to 15 hours, and some sources say 2C-B can last for up to twelve hours. 

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2C-I is illegal in the United States, Australia, Canada, and throughout the European Union. The US classifies it as a Schedule I substance, meaning the federal government considers it unsafe for use even under medical supervision due to it having high potential for abuse and no accepted medical use. All Schedule I substances are illegal to manufacture, possess, or distribute in the US.

The European Council issued an order requiring all EU member states to ban 2C-I in 2003. The United States banned 2C-I, along with synthetic marijuana (“K2” or “Spice”), synthetic cathinones (“Bath salts”), and several other 2C drugs when Congress passed the Synthetic Drug Abuse Prevention Act in 2012. Australia listed 2C-I as a prohibited substance in 2015, and Canada followed suit in 2016.


In the event of an emergency, please dial local emergency services. For emergency services related to substance abuse in the U.S., please dial the Substance Abuse and Mental Health Services Administration National Helpline at +1-(800) 662-4357.

This article is intended for harm reduction purposes and should not be used in place of medical advice. DoubleBlind does not advocate participating in illicit activities. Always consult your local drug laws before engaging with any unregulated substance.

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DoubleBlind is a trusted resource for news, evidence-based education, and reporting on psychedelics. We work with leading medical professionals, scientific researchers, journalists, mycologists, indigenous stewards, and cultural pioneers. Read about our editorial policy and fact-checking process here.

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DoubleBlind Magazine does not encourage or condone any illegal activities, including but not limited to the use of illegal substances. We do not provide mental health, clinical, or medical services. We are not a substitute for medical, psychological, or psychiatric diagnosis, treatment, or advice. If you are in a crisis or if you or any other person may be in danger or experiencing a mental health emergency, immediately call 911 or your local emergency resources. If you are considering suicide, please call 988 to connect with the National Suicide Prevention Lifeline.

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